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# Contributing to SDL
We appreciate your interest in contributing to SDL, this document will describe how to report bugs, contribute code or ideas or edit documentation.
**Table Of Contents**
- [Filing a GitHub issue](#filing-a-github-issue)
- [Reporting a bug](#reporting-a-bug)
- [Suggesting enhancements](#suggesting-enhancements)
- [Contributing code](#contributing-code)
- [Forking the project](#forking-the-project)
- [Following the style guide](#following-the-style-guide)
- [Running the tests](#running-the-tests)
- [Opening a pull request](#opening-a-pull-request)
- [Contributing to the documentation](#contributing-to-the-documentation)
- [Editing a function documentation](#editing-a-function-documentation)
- [Editing the wiki](#editing-the-wiki)
## Filing a GitHub issue
### Reporting a bug
If you think you have found a bug and would like to report it, here are the steps you should take:
- Before opening a new issue, ensure your bug has not already been reported on the [GitHub Issues page](https://github.com/libsdl-org/SDL/issues).
- On the issue tracker, click on [New Issue](https://github.com/libsdl-org/SDL/issues/new).
- Include details about your environment, such as your Operating System and SDL version.
- If possible, provide a small example that reproduces your bug.
### Suggesting enhancements
If you want to suggest changes for the project, here are the steps you should take:
- Check if the suggestion has already been made on:
- the [issue tracker](https://github.com/libsdl-org/SDL/issues);
- the [discourse forum](https://discourse.libsdl.org/);
- or if a [pull request](https://github.com/libsdl-org/SDL/pulls) already exists.
- On the issue tracker, click on [New Issue](https://github.com/libsdl-org/SDL/issues/new).
- Describe what change you would like to happen.
## Contributing code
This section will cover how the process of forking the project, making a change and opening a pull request.
### Forking the project
The first step consists in making a fork of the project, this is only necessary for the first contribution.
Head over to https://github.com/libsdl-org/SDL and click on the `Fork` button in the top right corner of your screen, you may leave the fields unchanged and click `Create Fork`.
You will be redirected to your fork of the repository, click the green `Code` button and copy the git clone link.
If you had already forked the repository, you may update it from the web page using the `Fetch upstream` button.
### Following the style guide
Code formatting is done using a custom `.clang-format` file, you can learn more about how to run it [here](https://clang.llvm.org/docs/ClangFormat.html).
Some legacy code may not be formatted, as such avoid formatting the whole file at once and only format around your changes.
For your commit message to be properly displayed on GitHub, it should contain:
- A short description of the commit of 50 characters or less on the first line.
- If necessary, add a blank line followed by a long description, each line should be 72 characters or less.
For example:
```
Fix crash in SDL_FooBar.
This addresses the issue #123456 by making sure Foo was successful
before calling Bar.
```
### Running the tests
Tests allow you to verify if your changes did not break any behaviour, here are the steps to follow:
- Before pushing, run the `testautomation` suite on your machine, there should be no more failing tests after your change than before.
- After pushing to your fork, Continuous Integration (GitHub Actions) will ensure compilation and tests still pass on other systems.
### Opening a pull request
- Head over to your fork's GitHub page.
- Click on the `Contribute` button and `Open Pull Request`.
- Fill out the pull request template.
- If any changes are requested, you can add new commits to your fork and they will be automatically added to the pull request.
## Contributing to the documentation
### Editing a function documentation
The wiki documentation for API functions is synchronised from the headers' doxygen comments. As such, all modifications to syntax; function parameters; return value; version; related functions should be done in the header directly.
### Editing the wiki
Other changes to the wiki should done directly from https://wiki.libsdl.org/
Android
================================================================================
Matt Styles wrote a tutorial on building SDL for Android with Visual Studio:
http://trederia.blogspot.de/2017/03/building-sdl2-for-android-with-visual.html
The rest of this README covers the Android gradle style build process.
If you are using the older ant build process, it is no longer officially
supported, but you can use the "android-project-ant" directory as a template.
Requirements
================================================================================
Android SDK (version 34 or later)
https://developer.android.com/sdk/index.html
Android NDK r15c or later
https://developer.android.com/tools/sdk/ndk/index.html
Minimum API level supported by SDL: 19 (Android 4.4)
How the port works
================================================================================
- Android applications are Java-based, optionally with parts written in C
- As SDL apps are C-based, we use a small Java shim that uses JNI to talk to
the SDL library
- This means that your application C code must be placed inside an Android
Java project, along with some C support code that communicates with Java
- This eventually produces a standard Android .apk package
The Android Java code implements an "Activity" and can be found in:
android-project/app/src/main/java/org/libsdl/app/SDLActivity.java
The Java code loads your game code, the SDL shared library, and
dispatches to native functions implemented in the SDL library:
src/core/android/SDL_android.c
Building an app
================================================================================
For simple projects you can use the script located at build-scripts/androidbuild.sh
There's two ways of using it:
androidbuild.sh com.yourcompany.yourapp < sources.list
androidbuild.sh com.yourcompany.yourapp source1.c source2.c ...sourceN.c
sources.list should be a text file with a source file name in each line
Filenames should be specified relative to the current directory, for example if
you are in the build-scripts directory and want to create the testgles.c test, you'll
run:
./androidbuild.sh org.libsdl.testgles ../test/testgles.c
One limitation of this script is that all sources provided will be aggregated into
a single directory, thus all your source files should have a unique name.
Once the project is complete the script will tell you where the debug APK is located.
If you want to create a signed release APK, you can use the project created by this
utility to generate it.
Finally, a word of caution: re running androidbuild.sh wipes any changes you may have
done in the build directory for the app!
For more complex projects, follow these instructions:
1. Get the source code for SDL and copy the 'android-project' directory located at SDL/android-project to a suitable location. Also make sure to rename it to your project name (In these examples: YOURPROJECT).
(The 'android-project' directory can basically be seen as a sort of starting point for the android-port of your project. It contains the glue code between the Android Java 'frontend' and the SDL code 'backend'. It also contains some standard behaviour, like how events should be handled, which you will be able to change.)
2. Move or [symlink](https://en.wikipedia.org/wiki/Symbolic_link) the SDL directory into the "YOURPROJECT/app/jni" directory
(This is needed as the source of SDL has to be compiled by the Android compiler)
3. Edit "YOURPROJECT/app/jni/src/Android.mk" to include your source files.
(They should be separated by spaces after the "LOCAL_SRC_FILES := " declaration)
4a. If you want to use Android Studio, simply open your 'YOURPROJECT' directory and start building.
4b. If you want to build manually, run './gradlew installDebug' in the project directory. This compiles the .java, creates an .apk with the native code embedded, and installs it on any connected Android device
If you already have a project that uses CMake, the instructions change somewhat:
1. Do points 1 and 2 from the instruction above.
2. Edit "YOURPROJECT/app/build.gradle" to comment out or remove sections containing ndk-build
and uncomment the cmake sections. Add arguments to the CMake invocation as needed.
3. Edit "YOURPROJECT/app/jni/CMakeLists.txt" to include your project (it defaults to
adding the "src" subdirectory). Note that you'll have SDL2, SDL2main and SDL2-static
as targets in your project, so you should have "target_link_libraries(yourgame SDL2 SDL2main)"
in your CMakeLists.txt file. Also be aware that you should use add_library() instead of
add_executable() for the target containing your "main" function.
If you wish to use Android Studio, you can skip the last step.
4. Run './gradlew installDebug' or './gradlew installRelease' in the project directory. It will build and install your .apk on any
connected Android device
Here's an explanation of the files in the Android project, so you can customize them:
android-project/app
build.gradle - build info including the application version and SDK
src/main/AndroidManifest.xml - package manifest. Among others, it contains the class name of the main Activity and the package name of the application.
jni/ - directory holding native code
jni/Application.mk - Application JNI settings, including target platform and STL library
jni/Android.mk - Android makefile that can call recursively the Android.mk files in all subdirectories
jni/CMakeLists.txt - Top-level CMake project that adds SDL as a subproject
jni/SDL/ - (symlink to) directory holding the SDL library files
jni/SDL/Android.mk - Android makefile for creating the SDL shared library
jni/src/ - directory holding your C/C++ source
jni/src/Android.mk - Android makefile that you should customize to include your source code and any library references
jni/src/CMakeLists.txt - CMake file that you may customize to include your source code and any library references
src/main/assets/ - directory holding asset files for your application
src/main/res/ - directory holding resources for your application
src/main/res/mipmap-* - directories holding icons for different phone hardware
src/main/res/values/strings.xml - strings used in your application, including the application name
src/main/java/org/libsdl/app/SDLActivity.java - the Java class handling the initialization and binding to SDL. Be very careful changing this, as the SDL library relies on this implementation. You should instead subclass this for your application.
Customizing your application name
================================================================================
To customize your application name, edit AndroidManifest.xml and replace
"org.libsdl.app" with an identifier for your product package.
Then create a Java class extending SDLActivity and place it in a directory
under src matching your package, e.g.
src/com/gamemaker/game/MyGame.java
Here's an example of a minimal class file:
--- MyGame.java --------------------------
package com.gamemaker.game;
import org.libsdl.app.SDLActivity;
/**
* A sample wrapper class that just calls SDLActivity
*/
public class MyGame extends SDLActivity { }
------------------------------------------
Then replace "SDLActivity" in AndroidManifest.xml with the name of your
class, .e.g. "MyGame"
Customizing your application icon
================================================================================
Conceptually changing your icon is just replacing the "ic_launcher.png" files in
the drawable directories under the res directory. There are several directories
for different screen sizes.
Loading assets
================================================================================
Any files you put in the "app/src/main/assets" directory of your project
directory will get bundled into the application package and you can load
them using the standard functions in SDL_rwops.h.
There are also a few Android specific functions that allow you to get other
useful paths for saving and loading data:
* SDL_AndroidGetInternalStoragePath()
* SDL_AndroidGetExternalStorageState()
* SDL_AndroidGetExternalStoragePath()
See SDL_system.h for more details on these functions.
The asset packaging system will, by default, compress certain file extensions.
SDL includes two asset file access mechanisms, the preferred one is the so
called "File Descriptor" method, which is faster and doesn't involve the Dalvik
GC, but given this method does not work on compressed assets, there is also the
"Input Stream" method, which is automatically used as a fall back by SDL. You
may want to keep this fact in mind when building your APK, specially when large
files are involved.
For more information on which extensions get compressed by default and how to
disable this behaviour, see for example:
http://ponystyle.com/blog/2010/03/26/dealing-with-asset-compression-in-android-apps/
Pause / Resume behaviour
================================================================================
If SDL_HINT_ANDROID_BLOCK_ON_PAUSE hint is set (the default),
the event loop will block itself when the app is paused (ie, when the user
returns to the main Android dashboard). Blocking is better in terms of battery
use, and it allows your app to spring back to life instantaneously after resume
(versus polling for a resume message).
Upon resume, SDL will attempt to restore the GL context automatically.
In modern devices (Android 3.0 and up) this will most likely succeed and your
app can continue to operate as it was.
However, there's a chance (on older hardware, or on systems under heavy load),
where the GL context can not be restored. In that case you have to listen for
a specific message (SDL_RENDER_DEVICE_RESET) and restore your textures
manually or quit the app.
You should not use the SDL renderer API while the app going in background:
- SDL_APP_WILLENTERBACKGROUND:
after you read this message, GL context gets backed-up and you should not
use the SDL renderer API.
When this event is received, you have to set the render target to NULL, if you're using it.
(eg call SDL_SetRenderTarget(renderer, NULL))
- SDL_APP_DIDENTERFOREGROUND:
GL context is restored, and the SDL renderer API is available (unless you
receive SDL_RENDER_DEVICE_RESET).
Mouse / Touch events
================================================================================
In some case, SDL generates synthetic mouse (resp. touch) events for touch
(resp. mouse) devices.
To enable/disable this behavior, see SDL_hints.h:
- SDL_HINT_TOUCH_MOUSE_EVENTS
- SDL_HINT_MOUSE_TOUCH_EVENTS
Misc
================================================================================
For some device, it appears to works better setting explicitly GL attributes
before creating a window:
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 5);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 6);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 5);
Threads and the Java VM
================================================================================
For a quick tour on how Linux native threads interoperate with the Java VM, take
a look here: https://developer.android.com/guide/practices/jni.html
If you want to use threads in your SDL app, it's strongly recommended that you
do so by creating them using SDL functions. This way, the required attach/detach
handling is managed by SDL automagically. If you have threads created by other
means and they make calls to SDL functions, make sure that you call
Android_JNI_SetupThread() before doing anything else otherwise SDL will attach
your thread automatically anyway (when you make an SDL call), but it'll never
detach it.
If you ever want to use JNI in a native thread (created by "SDL_CreateThread()"),
it won't be able to find your java class and method because of the java class loader
which is different for native threads, than for java threads (eg your "main()").
the work-around is to find class/method, in you "main()" thread, and to use them
in your native thread.
see:
https://developer.android.com/training/articles/perf-jni#faq:-why-didnt-findclass-find-my-class
Using STL
================================================================================
You can use STL in your project by creating an Application.mk file in the jni
folder and adding the following line:
APP_STL := c++_shared
For more information go here:
https://developer.android.com/ndk/guides/cpp-support
Using the emulator
================================================================================
There are some good tips and tricks for getting the most out of the
emulator here: https://developer.android.com/tools/devices/emulator.html
Especially useful is the info on setting up OpenGL ES 2.0 emulation.
Notice that this software emulator is incredibly slow and needs a lot of disk space.
Using a real device works better.
Troubleshooting
================================================================================
You can see if adb can see any devices with the following command:
adb devices
You can see the output of log messages on the default device with:
adb logcat
You can push files to the device with:
adb push local_file remote_path_and_file
You can push files to the SD Card at /sdcard, for example:
adb push moose.dat /sdcard/moose.dat
You can see the files on the SD card with a shell command:
adb shell ls /sdcard/
You can start a command shell on the default device with:
adb shell
You can remove the library files of your project (and not the SDL lib files) with:
ndk-build clean
You can do a build with the following command:
ndk-build
You can see the complete command line that ndk-build is using by passing V=1 on the command line:
ndk-build V=1
If your application crashes in native code, you can use ndk-stack to get a symbolic stack trace:
https://developer.android.com/ndk/guides/ndk-stack
If you want to go through the process manually, you can use addr2line to convert the
addresses in the stack trace to lines in your code.
For example, if your crash looks like this:
I/DEBUG ( 31): signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 400085d0
I/DEBUG ( 31): r0 00000000 r1 00001000 r2 00000003 r3 400085d4
I/DEBUG ( 31): r4 400085d0 r5 40008000 r6 afd41504 r7 436c6a7c
I/DEBUG ( 31): r8 436c6b30 r9 435c6fb0 10 435c6f9c fp 4168d82c
I/DEBUG ( 31): ip 8346aff0 sp 436c6a60 lr afd1c8ff pc afd1c902 cpsr 60000030
I/DEBUG ( 31): #00 pc 0001c902 /system/lib/libc.so
I/DEBUG ( 31): #01 pc 0001ccf6 /system/lib/libc.so
I/DEBUG ( 31): #02 pc 000014bc /data/data/org.libsdl.app/lib/libmain.so
I/DEBUG ( 31): #03 pc 00001506 /data/data/org.libsdl.app/lib/libmain.so
You can see that there's a crash in the C library being called from the main code.
I run addr2line with the debug version of my code:
arm-eabi-addr2line -C -f -e obj/local/armeabi/libmain.so
and then paste in the number after "pc" in the call stack, from the line that I care about:
000014bc
I get output from addr2line showing that it's in the quit function, in testspriteminimal.c, on line 23.
You can add logging to your code to help show what's happening:
#include <android/log.h>
__android_log_print(ANDROID_LOG_INFO, "foo", "Something happened! x = %d", x);
If you need to build without optimization turned on, you can create a file called
"Application.mk" in the jni directory, with the following line in it:
APP_OPTIM := debug
Memory debugging
================================================================================
The best (and slowest) way to debug memory issues on Android is valgrind.
Valgrind has support for Android out of the box, just grab code using:
svn co svn://svn.valgrind.org/valgrind/trunk valgrind
... and follow the instructions in the file README.android to build it.
One thing I needed to do on Mac OS X was change the path to the toolchain,
and add ranlib to the environment variables:
export RANLIB=$NDKROOT/toolchains/arm-linux-androideabi-4.4.3/prebuilt/darwin-x86/bin/arm-linux-androideabi-ranlib
Once valgrind is built, you can create a wrapper script to launch your
application with it, changing org.libsdl.app to your package identifier:
--- start_valgrind_app -------------------
#!/system/bin/sh
export TMPDIR=/data/data/org.libsdl.app
exec /data/local/Inst/bin/valgrind --log-file=/sdcard/valgrind.log --error-limit=no $*
------------------------------------------
Then push it to the device:
adb push start_valgrind_app /data/local
and make it executable:
adb shell chmod 755 /data/local/start_valgrind_app
and tell Android to use the script to launch your application:
adb shell setprop wrap.org.libsdl.app "logwrapper /data/local/start_valgrind_app"
If the setprop command says "could not set property", it's likely that
your package name is too long and you should make it shorter by changing
AndroidManifest.xml and the path to your class file in android-project/src
You can then launch your application normally and waaaaaaaiiittt for it.
You can monitor the startup process with the logcat command above, and
when it's done (or even while it's running) you can grab the valgrind
output file:
adb pull /sdcard/valgrind.log
When you're done instrumenting with valgrind, you can disable the wrapper:
adb shell setprop wrap.org.libsdl.app ""
Graphics debugging
================================================================================
If you are developing on a compatible Tegra-based tablet, NVidia provides
Tegra Graphics Debugger at their website. Because SDL2 dynamically loads EGL
and GLES libraries, you must follow their instructions for installing the
interposer library on a rooted device. The non-rooted instructions are not
compatible with applications that use SDL2 for video.
The Tegra Graphics Debugger is available from NVidia here:
https://developer.nvidia.com/tegra-graphics-debugger
Why is API level 19 the minimum required?
================================================================================
The latest NDK toolchain doesn't support targeting earlier than API level 19.
As of this writing, according to https://www.composables.com/tools/distribution-chart
about 99.7% of the Android devices accessing Google Play support API level 19 or
higher (August 2023).
A note regarding the use of the "dirty rectangles" rendering technique
================================================================================
If your app uses a variation of the "dirty rectangles" rendering technique,
where you only update a portion of the screen on each frame, you may notice a
variety of visual glitches on Android, that are not present on other platforms.
This is caused by SDL's use of EGL as the support system to handle OpenGL ES/ES2
contexts, in particular the use of the eglSwapBuffers function. As stated in the
documentation for the function "The contents of ancillary buffers are always
undefined after calling eglSwapBuffers".
Setting the EGL_SWAP_BEHAVIOR attribute of the surface to EGL_BUFFER_PRESERVED
is not possible for SDL as it requires EGL 1.4, available only on the API level
17+, so the only workaround available on this platform is to redraw the entire
screen each frame.
Reference: http://www.khronos.org/registry/egl/specs/EGLTechNote0001.html
Ending your application
================================================================================
Two legitimate ways:
- return from your main() function. Java side will automatically terminate the
Activity by calling Activity.finish().
- Android OS can decide to terminate your application by calling onDestroy()
(see Activity life cycle). Your application will receive a SDL_QUIT event you
can handle to save things and quit.
Don't call exit() as it stops the activity badly.
NB: "Back button" can be handled as a SDL_KEYDOWN/UP events, with Keycode
SDLK_AC_BACK, for any purpose.
Known issues
================================================================================
- The number of buttons reported for each joystick is hardcoded to be 36, which
is the current maximum number of buttons Android can report.
# CMake
(www.cmake.org)
SDL's build system was traditionally based on autotools. Over time, this
approach has suffered from several issues across the different supported
platforms.
To solve these problems, a new build system based on CMake was introduced.
It is developed in parallel to the legacy autotools build system, so users
can experiment with it without complication.
The CMake build system is supported on the following platforms:
* FreeBSD
* Linux
* Microsoft Visual C
* MinGW and Msys
* macOS, iOS, and tvOS, with support for XCode
* Android
* Emscripten
* RiscOS
* Playstation Vita
## Building SDL
Assuming the source for SDL is located at `~/sdl`
```sh
cd ~
mkdir build
cd build
cmake ~/sdl
cmake --build .
```
This will build the static and dynamic versions of SDL in the `~/build` directory.
Installation can be done using:
```sh
cmake --install . # '--install' requires CMake 3.15, or newer
```
## Including SDL in your project
SDL can be included in your project in 2 major ways:
- using a system SDL library, provided by your (*nix) distribution or a package manager
- using a vendored SDL library: this is SDL copied or symlinked in a subfolder.
The following CMake script supports both, depending on the value of `MYGAME_VENDORED`.
```cmake
cmake_minimum_required(VERSION 3.5)
project(mygame)
# Create an option to switch between a system sdl library and a vendored sdl library
option(MYGAME_VENDORED "Use vendored libraries" OFF)
if(MYGAME_VENDORED)
add_subdirectory(vendored/sdl EXCLUDE_FROM_ALL)
else()
# 1. Look for a SDL2 package, 2. look for the SDL2 component and 3. fail if none can be found
find_package(SDL2 REQUIRED CONFIG REQUIRED COMPONENTS SDL2)
# 1. Look for a SDL2 package, 2. Look for the SDL2maincomponent and 3. DO NOT fail when SDL2main is not available
find_package(SDL2 REQUIRED CONFIG COMPONENTS SDL2main)
endif()
# Create your game executable target as usual
add_executable(mygame WIN32 mygame.c)
# SDL2::SDL2main may or may not be available. It is e.g. required by Windows GUI applications
if(TARGET SDL2::SDL2main)
# It has an implicit dependency on SDL2 functions, so it MUST be added before SDL2::SDL2 (or SDL2::SDL2-static)
target_link_libraries(mygame PRIVATE SDL2::SDL2main)
endif()
# Link to the actual SDL2 library. SDL2::SDL2 is the shared SDL library, SDL2::SDL2-static is the static SDL libarary.
target_link_libraries(mygame PRIVATE SDL2::SDL2)
```
### A system SDL library
For CMake to find SDL, it must be installed in [a default location CMake is looking for](https://cmake.org/cmake/help/latest/command/find_package.html#config-mode-search-procedure).
The following components are available, to be used as an argument of `find_package`.
| Component name | Description |
|----------------|--------------------------------------------------------------------------------------------|
| SDL2 | The SDL2 shared library, available through the `SDL2::SDL2` target [^SDL_TARGET_EXCEPTION] |
| SDL2-static | The SDL2 static library, available through the `SDL2::SDL2-static` target |
| SDL2main | The SDL2main static library, available through the `SDL2::SDL2main` target |
| SDL2test | The SDL2test static library, available through the `SDL2::SDL2test` target |
### Using a vendored SDL
This only requires a copy of SDL in a subdirectory.
## CMake configuration options for platforms
### iOS/tvOS
CMake 3.14+ natively includes support for iOS and tvOS. SDL binaries may be built
using Xcode or Make, possibly among other build-systems.
When using a recent version of CMake (3.14+), it should be possible to:
- build SDL for iOS, both static and dynamic
- build SDL test apps (as iOS/tvOS .app bundles)
- generate a working SDL_config.h for iOS (using SDL_config.h.cmake as a basis)
To use, set the following CMake variables when running CMake's configuration stage:
- `CMAKE_SYSTEM_NAME=<OS>` (either `iOS` or `tvOS`)
- `CMAKE_OSX_SYSROOT=<SDK>` (examples: `iphoneos`, `iphonesimulator`, `iphoneos12.4`, `/full/path/to/iPhoneOS.sdk`,
`appletvos`, `appletvsimulator`, `appletvos12.4`, `/full/path/to/AppleTVOS.sdk`, etc.)
- `CMAKE_OSX_ARCHITECTURES=<semicolon-separated list of CPU architectures>` (example: "arm64;armv7s;x86_64")
#### Examples
- for iOS-Simulator, using the latest, installed SDK:
```bash
cmake ~/sdl -DCMAKE_SYSTEM_NAME=iOS -DCMAKE_OSX_SYSROOT=iphonesimulator -DCMAKE_OSX_ARCHITECTURES=x86_64
```
- for iOS-Device, using the latest, installed SDK, 64-bit only
```bash
cmake ~/sdl -DCMAKE_SYSTEM_NAME=iOS -DCMAKE_OSX_SYSROOT=iphoneos -DCMAKE_OSX_ARCHITECTURES=arm64
```
- for iOS-Device, using the latest, installed SDK, mixed 32/64 bit
```cmake
cmake ~/sdl -DCMAKE_SYSTEM_NAME=iOS -DCMAKE_OSX_SYSROOT=iphoneos -DCMAKE_OSX_ARCHITECTURES="arm64;armv7s"
```
- for iOS-Device, using a specific SDK revision (iOS 12.4, in this example):
```cmake
cmake ~/sdl -DCMAKE_SYSTEM_NAME=iOS -DCMAKE_OSX_SYSROOT=iphoneos12.4 -DCMAKE_OSX_ARCHITECTURES=arm64
```
- for iOS-Simulator, using the latest, installed SDK, and building SDL test apps (as .app bundles):
```cmake
cmake ~/sdl -DSDL_TESTS=1 -DCMAKE_SYSTEM_NAME=iOS -DCMAKE_OSX_SYSROOT=iphonesimulator -DCMAKE_OSX_ARCHITECTURES=x86_64
```
- for tvOS-Simulator, using the latest, installed SDK:
```cmake
cmake ~/sdl -DCMAKE_SYSTEM_NAME=tvOS -DCMAKE_OSX_SYSROOT=appletvsimulator -DCMAKE_OSX_ARCHITECTURES=x86_64
```
- for tvOS-Device, using the latest, installed SDK:
```cmake
cmake ~/sdl -DCMAKE_SYSTEM_NAME=tvOS -DCMAKE_OSX_SYSROOT=appletvos -DCMAKE_OSX_ARCHITECTURES=arm64`
```
[^SDL_TARGET_EXCEPTION]: `SDL2::SDL2` can be an ALIAS to a static `SDL2::SDL2-static` target for multiple reasons.
DirectFB
========
Supports:
- Hardware YUV overlays
- OpenGL - software only
- 2D/3D accelerations (depends on directfb driver)
- multiple displays
- windows
What you need:
* DirectFB 1.0.1, 1.2.x, 1.3.0
* Kernel-Framebuffer support: required: vesafb, radeonfb ....
* Mesa 7.0.x - optional for OpenGL
The `/etc/directfbrc` file should contain the following lines to make
your joystick work and avoid crashes:
```
disable-module=joystick
disable-module=cle266
disable-module=cyber5k
no-linux-input-grab
```
To disable to use x11 backend when DISPLAY variable is found use
```
export SDL_DIRECTFB_X11_CHECK=0
```
To disable the use of linux input devices, i.e. multimice/multikeyboard support,
use
```
export SDL_DIRECTFB_LINUX_INPUT=0
```
To use hardware accelerated YUV-overlays for YUV-textures, use:
```
export SDL_DIRECTFB_YUV_DIRECT=1
```
This is disabled by default. It will only support one
YUV texture, namely the first. Every other YUV texture will be
rendered in software.
In addition, you may use (directfb-1.2.x)
```
export SDL_DIRECTFB_YUV_UNDERLAY=1
```
to make the YUV texture an underlay. This will make the cursor to
be shown.
Simple Window Manager
=====================
The driver has support for a very, very basic window manager you may
want to use when running with `wm=default`. Use
```
export SDL_DIRECTFB_WM=1
```
to enable basic window borders. In order to have the window title rendered,
you need to have the following font installed:
```
/usr/share/fonts/truetype/freefont/FreeSans.ttf
```
OpenGL Support
==============
The following instructions will give you *software* OpenGL. However this
works at least on all directfb supported platforms.
As of this writing 20100802 you need to pull Mesa from git and do the following:
```
git clone git://anongit.freedesktop.org/git/mesa/mesa
cd mesa
git checkout 2c9fdaf7292423c157fc79b5ce43f0f199dd753a
```
Edit `configs/linux-directfb` so that the Directories-section looks like this:
```
# Directories
SRC_DIRS = mesa glu
GLU_DIRS = sgi
DRIVER_DIRS = directfb
PROGRAM_DIRS =
```
Then do the following:
```
make linux-directfb
make
echo Installing - please enter sudo pw.
sudo make install INSTALL_DIR=/usr/local/dfb_GL
cd src/mesa/drivers/directfb
make
sudo make install INSTALL_DIR=/usr/local/dfb_GL
```
To run the SDL - testprograms:
```
export SDL_VIDEODRIVER=directfb
export LD_LIBRARY_PATH=/usr/local/dfb_GL/lib
export LD_PRELOAD=/usr/local/dfb_GL/libGL.so.7
./testgl
```
# Dynamic API
Originally posted on Ryan's Google+ account.
Background:
- The Steam Runtime has (at least in theory) a really kick-ass build of SDL2,
but developers are shipping their own SDL2 with individual Steam games.
These games might stop getting updates, but a newer SDL2 might be needed later.
Certainly we'll always be fixing bugs in SDL, even if a new video target isn't
ever needed, and these fixes won't make it to a game shipping its own SDL.
- Even if we replace the SDL2 in those games with a compatible one, that is to
say, edit a developer's Steam depot (yuck!), there are developers that are
statically linking SDL2 that we can't do this for. We can't even force the
dynamic loader to ignore their SDL2 in this case, of course.
- If you don't ship an SDL2 with the game in some form, people that disabled the
Steam Runtime, or just tried to run the game from the command line instead of
Steam might find themselves unable to run the game, due to a missing dependency.
- If you want to ship on non-Steam platforms like GOG or Humble Bundle, or target
generic Linux boxes that may or may not have SDL2 installed, you have to ship
the library or risk a total failure to launch. So now, you might have to have
a non-Steam build plus a Steam build (that is, one with and one without SDL2
included), which is inconvenient if you could have had one universal build
that works everywhere.
- We like the zlib license, but the biggest complaint from the open source
community about the license change is the static linking. The LGPL forced this
as a legal, not technical issue, but zlib doesn't care. Even those that aren't
concerned about the GNU freedoms found themselves solving the same problems:
swapping in a newer SDL to an older game often times can save the day.
Static linking stops this dead.
So here's what we did:
SDL now has, internally, a table of function pointers. So, this is what SDL_Init
now looks like:
```c
UInt32 SDL_Init(Uint32 flags)
{
return jump_table.SDL_Init(flags);
}
```
Except that is all done with a bunch of macro magic so we don't have to maintain
every one of these.
What is jump_table.SDL_init()? Eventually, that's a function pointer of the real
SDL_Init() that you've been calling all this time. But at startup, it looks more
like this:
```c
Uint32 SDL_Init_DEFAULT(Uint32 flags)
{
SDL_InitDynamicAPI();
return jump_table.SDL_Init(flags);
}
```
SDL_InitDynamicAPI() fills in jump_table with all the actual SDL function
pointers, which means that this `_DEFAULT` function never gets called again.
First call to any SDL function sets the whole thing up.
So you might be asking, what was the value in that? Isn't this what the operating
system's dynamic loader was supposed to do for us? Yes, but now we've got this
level of indirection, we can do things like this:
```bash
export SDL_DYNAMIC_API=/my/actual/libSDL-2.0.so.0
./MyGameThatIsStaticallyLinkedToSDL2
```
And now, this game that is statically linked to SDL, can still be overridden
with a newer, or better, SDL. The statically linked one will only be used as
far as calling into the jump table in this case. But in cases where no override
is desired, the statically linked version will provide its own jump table,
and everyone is happy.
So now:
- Developers can statically link SDL, and users can still replace it.
(We'd still rather you ship a shared library, though!)
- Developers can ship an SDL with their game, Valve can override it for, say,
new features on SteamOS, or distros can override it for their own needs,
but it'll also just work in the default case.
- Developers can ship the same package to everyone (Humble Bundle, GOG, etc),
and it'll do the right thing.
- End users (and Valve) can update a game's SDL in almost any case,
to keep abandoned games running on newer platforms.
- Everyone develops with SDL exactly as they have been doing all along.
Same headers, same ABI. Just get the latest version to enable this magic.
A little more about SDL_InitDynamicAPI():
Internally, InitAPI does some locking to make sure everything waits until a
single thread initializes everything (although even SDL_CreateThread() goes
through here before spinning a thread, too), and then decides if it should use
an external SDL library. If not, it sets up the jump table using the current
SDL's function pointers (which might be statically linked into a program, or in
a shared library of its own). If so, it loads that library and looks for and
calls a single function:
```c
SInt32 SDL_DYNAPI_entry(Uint32 version, void *table, Uint32 tablesize);
```
That function takes a version number (more on that in a moment), the address of
the jump table, and the size, in bytes, of the table.
Now, we've got policy here: this table's layout never changes; new stuff gets
added to the end. Therefore SDL_DYNAPI_entry() knows that it can provide all
the needed functions if tablesize <= sizeof its own jump table. If tablesize is
bigger (say, SDL 2.0.4 is trying to load SDL 2.0.3), then we know to abort, but
if it's smaller, we know we can provide the entire API that the caller needs.
The version variable is a failsafe switch.
Right now it's always 1. This number changes when there are major API changes
(so we know if the tablesize might be smaller, or entries in it have changed).
Right now SDL_DYNAPI_entry gives up if the version doesn't match, but it's not
inconceivable to have a small dispatch library that only supplies this one
function and loads different, otherwise-incompatible SDL libraries and has the
right one initialize the jump table based on the version. For something that
must generically catch lots of different versions of SDL over time, like the
Steam Client, this isn't a bad option.
Finally, I'm sure some people are reading this and thinking,
"I don't want that overhead in my project!"
To which I would point out that the extra function call through the jump table
probably wouldn't even show up in a profile, but lucky you: this can all be
disabled. You can build SDL without this if you absolutely must, but we would
encourage you not to do that. However, on heavily locked down platforms like
iOS, or maybe when debugging, it makes sense to disable it. The way this is
designed in SDL, you just have to change one #define, and the entire system
vaporizes out, and SDL functions exactly like it always did. Most of it is
macro magic, so the system is contained to one C file and a few headers.
However, this is on by default and you have to edit a header file to turn it
off. Our hopes is that if we make it easy to disable, but not too easy,
everyone will ultimately be able to get what they want, but we've gently
nudged everyone towards what we think is the best solution.
# Emscripten
(This documentation is not very robust; we will update and expand this later.)
## A quick note about audio
Modern web browsers will not permit web pages to produce sound before the
user has interacted with them; this is for several reasons, not the least
of which being that no one likes when a random browser tab suddenly starts
making noise and the user has to scramble to figure out which and silence
it.
To solve this, most browsers will refuse to let a web app use the audio
subsystem at all before the user has interacted with (clicked on) the page
in a meaningful way. SDL-based apps also have to deal with this problem; if
the user hasn't interacted with the page, SDL_OpenAudioDevice will fail.
There are two reasonable ways to deal with this: if you are writing some
sort of media player thing, where the user expects there to be a volume
control when you mouseover the canvas, just default that control to a muted
state; if the user clicks on the control to unmute it, on this first click,
open the audio device. This allows the media to play at start, the user can
reasonably opt-in to listening, and you never get access denied to the audio
device.
Many games do not have this sort of UI, and are more rigid about starting
audio along with everything else at the start of the process. For these, your
best bet is to write a little Javascript that puts up a "Click here to play!"
UI, and upon the user clicking, remove that UI and then call the Emscripten
app's main() function. As far as the application knows, the audio device was
available to be opened as soon as the program started, and since this magic
happens in a little Javascript, you don't have to change your C/C++ code at
all to make it happen.
Please see the discussion at https://github.com/libsdl-org/SDL/issues/6385
for some Javascript code to steal for this approach.
## Building SDL/emscripten
SDL currently requires at least Emscripten 3.1.35 to build. Newer versions
are likely to work, as well.
Build:
$ mkdir build
$ cd build
$ emconfigure ../configure --host=asmjs-unknown-emscripten --disable-assembly --disable-threads --disable-cpuinfo CFLAGS="-O2"
$ emmake make
Or with cmake:
$ mkdir build
$ cd build
$ emcmake cmake ..
$ emmake make
To build one of the tests:
$ cd test/
$ emcc -O2 --js-opts 0 -g4 testdraw2.c -I../include ../build/.libs/libSDL2.a ../build/libSDL2_test.a -o a.html
Uses GLES2 renderer or software
Some other SDL2 libraries can be easily built (assuming SDL2 is installed somewhere):
SDL_mixer (http://www.libsdl.org/projects/SDL_mixer/):
$ EMCONFIGURE_JS=1 emconfigure ../configure
build as usual...
SDL_gfx (http://cms.ferzkopp.net/index.php/software/13-sdl-gfx):
$ EMCONFIGURE_JS=1 emconfigure ../configure --disable-mmx
build as usual...
GDK
=====
This port allows SDL applications to run via Microsoft's Game Development Kit (GDK).
Windows (GDK) and Xbox One/Xbox Series (GDKX) are supported. Although most of the Xbox code is included in the public SDL source code, NDA access is required for a small number of source files. If you have access to GDKX, these required Xbox files are posted on the GDK forums [here](https://forums.xboxlive.com/questions/130003/).
Requirements
------------
* Microsoft Visual Studio 2022 (in theory, it should also work in 2017 or 2019, but this has not been tested)
* Microsoft GDK June 2022 or newer (public release [here](https://github.com/microsoft/GDK/releases/tag/June_2022))
* To publish a package or successfully authenticate a user, you will need to create an app id/configure services in Partner Center. However, for local testing purposes (without authenticating on Xbox Live), the identifiers used by the GDK test programs in the included solution will work.
Windows GDK Status
------
The Windows GDK port supports the full set of Win32 APIs, renderers, controllers, input devices, etc., as the normal Windows x64 build of SDL.
* Additionally, the GDK port adds the following:
* Compile-time platform detection for SDL programs. The `__GDK__` is `#define`d on every GDK platform, and the `__WINGDK__` is `#define`d on Windows GDK, specifically. (This distinction exists because other GDK platforms support a smaller subset of functionality. This allows you to mark code for "any" GDK separate from Windows GDK.)
* GDK-specific setup:
* Initializing/uninitializing the game runtime, and initializing Xbox Live services
* Creating a global task queue and setting it as the default for the process. When running any async operations, passing in `NULL` as the task queue will make the task get added to the global task queue.
* An implementation on `WinMain` that performs the above GDK setup (you should link against SDL2main.lib, as in Windows x64). If you are unable to do this, you can instead manually call `SDL_GDKRunApp` from your entry point, passing in your `SDL_main` function and `NULL` as the parameters.
* Global task queue callbacks are dispatched during `SDL_PumpEvents` (which is also called internally if using `SDL_PollEvent`).
* You can get the handle of the global task queue through `SDL_GDKGetTaskQueue`, if needed. When done with the queue, be sure to use `XTaskQueueCloseHandle` to decrement the reference count (otherwise it will cause a resource leak).
* What doesn't work:
* Compilation with anything other than through the included Visual C++ solution file
## VisualC-GDK Solution
The included `VisualC-GDK/SDL.sln` solution includes the following targets for the Gaming.Desktop.x64 configuration:
* SDL2 (DLL) - This is the typical SDL2.dll, but for Gaming.Desktop.x64.
* SDL2main (lib) - This contains a drop-in implementation of `WinMain` that is used as the entry point for GDK programs.
* tests/testgamecontroller - Standard SDL test program demonstrating controller functionality.
* tests/testgdk - GDK-specific test program that demonstrates using the global task queue to login a user into Xbox Live.
*NOTE*: As of the June 2022 GDK, you cannot test user logins without a valid Title ID and MSAAppId. You will need to manually change the identifiers in the `MicrosoftGame.config` to your valid IDs from Partner Center if you wish to test this.
* tests/testsprite2 - Standard SDL test program demonstrating sprite drawing functionality.
If you set one of the test programs as a startup project, you can run it directly from Visual Studio.
Windows GDK Setup, Detailed Steps
---------------------
These steps assume you already have a game using SDL that runs on Windows x64 along with a corresponding Visual Studio solution file for the x64 version. If you don't have this, it's easiest to use one of the test program vcxproj files in the `VisualC-GDK` directory as a starting point, though you will still need to do most of the steps below.
### 1. Add a Gaming.Desktop.x64 Configuration ###
In your game's existing Visual Studio Solution, go to Build > Configuration Manager. From the "Active solution platform" drop-down select "New...". From the drop-down list, select Gaming.Desktop.x64 and copy the settings from the x64 configuration.
### 2. Build SDL2 and SDL2main for GDK ###
Open `VisualC-GDK/SDL.sln` in Visual Studio, you need to build the SDL2 and SDL2main targets for the Gaming.Desktop.x64 platform (Release is recommended). You will need to copy/keep track of the `SDL2.dll`, `XCurl.dll` (which is output by Gaming.Desktop.x64), `SDL2.lib`, and `SDL2main.lib` output files for your game project.
*Alternatively*, you could setup your solution file to instead reference the SDL2/SDL2main project file targets from the SDL source, and add those projects as a dependency. This would mean that SDL2 and SDL2main would both be built when your game is built.
### 3. Configuring Project Settings ###
While the Gaming.Desktop.x64 configuration sets most of the required settings, there are some additional items to configure for your game project under the Gaming.Desktop.x64 Configuration:
* Under C/C++ > General > Additional Include Directories, make sure the `SDL/include` path is referenced
* Under Linker > General > Additional Library Directories, make sure to reference the path where the newly-built SDL2.lib and SDL2main.lib are
* Under Linker > Input > Additional Dependencies, you need the following:
* `SDL2.lib`
* `SDL2main.lib` (unless not using)
* `xgameruntime.lib`
* `../Microsoft.Xbox.Services.141.GDK.C.Thunks.lib`
* Note that in general, the GDK libraries depend on the MSVC C/C++ runtime, so there is no way to remove this dependency from a GDK program that links against GDK.
### 4. Setting up SDL_main ###
Rather than using your own implementation of `WinMain`, it's recommended that you instead `#include "SDL_main.h"` and declare a standard main function. If you are unable to do this, you can instead manually call `SDL_GDKRunApp` from your entry point, passing in your `SDL_main` function and `NULL` as the parameters.
### 5. Required DLLs ###
The game will not launch in the debugger unless required DLLs are included in the directory that contains the game's .exe file. You need to make sure that the following files are copied into the directory:
* Your SDL2.dll
* "$(Console_GRDKExtLibRoot)Xbox.Services.API.C\DesignTime\CommonConfiguration\Neutral\Lib\Release\Microsoft.Xbox.Services.141.GDK.C.Thunks.dll"
* XCurl.dll
You can either copy these in a post-build step, or you can add the dlls into the project and set its Configuration Properties > General > Item type to "Copy file," which will also copy them into the output directory.
### 6. Setting up MicrosoftGame.config ###
You can copy `VisualC-GDK/tests/testgdk/MicrosoftGame.config` and use that as a starting point in your project. Minimally, you will want to change the Executable Name attribute, the DefaultDisplayName, and the Description.
This file must be copied into the same directory as the game's .exe file. As with the DLLs, you can either use a post-build step or the "Copy file" item type.
For basic testing, you do not need to change anything else in `MicrosoftGame.config`. However, if you want to test any Xbox Live services (such as logging in users) _or_ publish a package, you will need to setup a Game app on Partner Center.
Then, you need to set the following values to the values from Partner Center:
* Identity tag - Name and Publisher attributes
* TitleId
* MSAAppId
### 7. Adding Required Logos
Several logo PNG files are required to be able to launch the game, even from the debugger. You can use the sample logos provided in `VisualC-GDK/logos`. As with the other files, they must be copied into the same directory as the game's .exe file.
### 8. Copying any Data Files ###
When debugging GDK games, there is no way to specify a working directory. Therefore, any required game data must also be copied into the output directory, likely in a post-build step.
### 9. Build and Run from Visual Studio ###
At this point, you should be able to build and run your game from the Visual Studio Debugger. If you get any linker errors, make sure you double-check that you referenced all the required libs.
If you are testing Xbox Live functionality, it's likely you will need to change to the Sandbox for your title. To do this:
1. Run "Desktop VS 2022 Gaming Command Prompt" from the Start Menu
2. Switch the sandbox name with:
`XblPCSandbox SANDBOX.#`
3. (To switch back to the retail sandbox):
`XblPCSandbox RETAIL`
### 10. Packaging and Installing Locally
You can use one of the test program's `PackageLayout.xml` as a starting point. Minimally, you will need to change the exe to the correct name and also reference any required game data. As with the other data files, it's easiest if you have this copy to the output directory, although it's not a requirement as you can specify relative paths to files.
To create the package:
1. Run "Desktop VS 2022 Gaming Command Prompt" from the Start Menu
2. `cd` to the directory containing the `PackageLayout.xml` with the correct paths (if you use the local path as in the sample package layout, this would be from your .exe output directory)
3. `mkdir Package` to create an output directory
4. To package the file into the `Package` directory, use:
`makepkg pack /f PackageLayout.xml /lt /d . /nogameos /pc /pd Package`
5. To install the package, use:
`wdapp install PACKAGENAME.msixvc`
6. Once the package is installed, you can run it from the start menu.
7. As with when running from Visual Studio, if you need to test any Xbox Live functionality you must switch to the correct sandbox.
Troubleshooting
---------------
#### Xbox Live Login does not work
As of June 2022 GDK, you must have a valid Title Id and MSAAppId in order to test Xbox Live functionality such as user login. Make sure these are set correctly in the `MicrosoftGame.config`. This means that even testgdk will not let you login without setting these properties to valid values.
Furthermore, confirm that your PC is set to the correct sandbox.
#### "The current user has already installed an unpackaged version of this app. A packaged version cannot replace this." error when installing
Prior to June 2022 GDK, running from the Visual Studio debugger would still locally register the app (and it would appear on the start menu). To fix this, you have to uninstall it (it's simplest to right click on it from the start menu to uninstall it).
Dollar Gestures
===========================================================================
SDL provides an implementation of the $1 gesture recognition system. This allows for recording, saving, loading, and performing single stroke gestures.
Gestures can be performed with any number of fingers (the centroid of the fingers must follow the path of the gesture), but the number of fingers must be constant (a finger cannot go down in the middle of a gesture). The path of a gesture is considered the path from the time when the final finger went down, to the first time any finger comes up.
Dollar gestures are assigned an Id based on a hash function. This is guaranteed to remain constant for a given gesture. There is a (small) chance that two different gestures will be assigned the same ID. In this case, simply re-recording one of the gestures should result in a different ID.
Recording:
----------
To begin recording on a touch device call:
SDL_RecordGesture(SDL_TouchID touchId), where touchId is the id of the touch device you wish to record on, or -1 to record on all connected devices.
Recording terminates as soon as a finger comes up. Recording is acknowledged by an SDL_DOLLARRECORD event.
A SDL_DOLLARRECORD event is a dgesture with the following fields:
* event.dgesture.touchId - the Id of the touch used to record the gesture.
* event.dgesture.gestureId - the unique id of the recorded gesture.
Performing:
-----------
As long as there is a dollar gesture assigned to a touch, every finger-up event will also cause an SDL_DOLLARGESTURE event with the following fields:
* event.dgesture.touchId - the Id of the touch which performed the gesture.
* event.dgesture.gestureId - the unique id of the closest gesture to the performed stroke.
* event.dgesture.error - the difference between the gesture template and the actual performed gesture. Lower error is a better match.
* event.dgesture.numFingers - the number of fingers used to draw the stroke.
Most programs will want to define an appropriate error threshold and check to be sure that the error of a gesture is not abnormally high (an indicator that no gesture was performed).
Saving:
-------
To save a template, call SDL_SaveDollarTemplate(gestureId, dst) where gestureId is the id of the gesture you want to save, and dst is an SDL_RWops pointer to the file where the gesture will be stored.
To save all currently loaded templates, call SDL_SaveAllDollarTemplates(dst) where dst is an SDL_RWops pointer to the file where the gesture will be stored.
Both functions return the number of gestures successfully saved.
Loading:
--------
To load templates from a file, call SDL_LoadDollarTemplates(touchId,src) where touchId is the id of the touch to load to (or -1 to load to all touch devices), and src is an SDL_RWops pointer to a gesture save file.
SDL_LoadDollarTemplates returns the number of templates successfully loaded.
===========================================================================
Multi Gestures
===========================================================================
SDL provides simple support for pinch/rotate/swipe gestures.
Every time a finger is moved an SDL_MULTIGESTURE event is sent with the following fields:
* event.mgesture.touchId - the Id of the touch on which the gesture was performed.
* event.mgesture.x - the normalized x coordinate of the gesture. (0..1)
* event.mgesture.y - the normalized y coordinate of the gesture. (0..1)
* event.mgesture.dTheta - the amount that the fingers rotated during this motion.
* event.mgesture.dDist - the amount that the fingers pinched during this motion.
* event.mgesture.numFingers - the number of fingers used in the gesture.
===========================================================================
Notes
===========================================================================
For a complete example see test/testgesture.c
Please direct questions/comments to:
jim.tla+sdl_touch@gmail.com
git
=========
The latest development version of SDL is available via git.
Git allows you to get up-to-the-minute fixes and enhancements;
as a developer works on a source tree, you can use "git" to mirror that
source tree instead of waiting for an official release. Please look
at the Git website ( https://git-scm.com/ ) for more
information on using git, where you can also download software for
macOS, Windows, and Unix systems.
git clone https://github.com/libsdl-org/SDL
If you are building SDL via configure, you will need to run autogen.sh
before running configure.
There is a web interface to the Git repository at:
http://github.com/libsdl-org/SDL/
We are no longer hosted in Mercurial. Please see README-git.md for details.
Thanks!
iOS
======
Building the Simple DirectMedia Layer for iOS 9.0+
==============================================================================
Requirements: Mac OS X 10.9 or later and the iOS 9.0 or newer SDK.
Instructions:
1. Open SDL.xcodeproj (located in Xcode/SDL) in Xcode.
2. Select your desired target, and hit build.
Using the Simple DirectMedia Layer for iOS
==============================================================================
1. Run Xcode and create a new project using the iOS Game template, selecting the Objective C language and Metal game technology.
2. In the main view, delete all files except for Assets and LaunchScreen
3. Right click the project in the main view, select "Add Files...", and add the SDL project, Xcode/SDL/SDL.xcodeproj
4. Select the project in the main view, go to the "Info" tab and under "Custom iOS Target Properties" remove the line "Main storyboard file base name"
5. Select the project in the main view, go to the "Build Settings" tab, select "All", and edit "Header Search Path" and drag over the SDL "Public Headers" folder from the left
6. Select the project in the main view, go to the "Build Phases" tab, select "Link Binary With Libraries", and add SDL2.framework from "Framework-iOS"
7. Select the project in the main view, go to the "General" tab, scroll down to "Frameworks, Libraries, and Embedded Content", and select "Embed & Sign" for the SDL library.
8. In the main view, expand SDL -> Library Source -> main -> uikit and drag SDL_uikit_main.c into your game files
9. Add the source files that you would normally have for an SDL program, making sure to have #include "SDL.h" at the top of the file containing your main() function.
10. Add any assets that your application needs.
11. Enjoy!
TODO: Add information regarding App Store requirements such as icons, etc.
Notes -- Retina / High-DPI and window sizes
==============================================================================
Window and display mode sizes in SDL are in "screen coordinates" (or "points",
in Apple's terminology) rather than in pixels. On iOS this means that a window
created on an iPhone 6 will have a size in screen coordinates of 375 x 667,
rather than a size in pixels of 750 x 1334. All iOS apps are expected to
size their content based on screen coordinates / points rather than pixels,
as this allows different iOS devices to have different pixel densities
(Retina versus non-Retina screens, etc.) without apps caring too much.
By default SDL will not use the full pixel density of the screen on
Retina/high-dpi capable devices. Use the SDL_WINDOW_ALLOW_HIGHDPI flag when
creating your window to enable high-dpi support.
When high-dpi support is enabled, SDL_GetWindowSize() and display mode sizes
will still be in "screen coordinates" rather than pixels, but the window will
have a much greater pixel density when the device supports it, and the
SDL_GL_GetDrawableSize() or SDL_GetRendererOutputSize() functions (depending on
whether raw OpenGL or the SDL_Render API is used) can be queried to determine
the size in pixels of the drawable screen framebuffer.
Some OpenGL ES functions such as glViewport expect sizes in pixels rather than
sizes in screen coordinates. When doing 2D rendering with OpenGL ES, an
orthographic projection matrix using the size in screen coordinates
(SDL_GetWindowSize()) can be used in order to display content at the same scale
no matter whether a Retina device is used or not.
Notes -- Application events
==============================================================================
On iOS the application goes through a fixed life cycle and you will get
notifications of state changes via application events. When these events
are delivered you must handle them in an event callback because the OS may
not give you any processing time after the events are delivered.
e.g.
int HandleAppEvents(void *userdata, SDL_Event *event)
{
switch (event->type)
{
case SDL_APP_TERMINATING:
/* Terminate the app.
Shut everything down before returning from this function.
*/
return 0;
case SDL_APP_LOWMEMORY:
/* You will get this when your app is paused and iOS wants more memory.
Release as much memory as possible.
*/
return 0;
case SDL_APP_WILLENTERBACKGROUND:
/* Prepare your app to go into the background. Stop loops, etc.
This gets called when the user hits the home button, or gets a call.
*/
return 0;
case SDL_APP_DIDENTERBACKGROUND:
/* This will get called if the user accepted whatever sent your app to the background.
If the user got a phone call and canceled it, you'll instead get an SDL_APP_DIDENTERFOREGROUND event and restart your loops.
When you get this, you have 5 seconds to save all your state or the app will be terminated.
Your app is NOT active at this point.
*/
return 0;
case SDL_APP_WILLENTERFOREGROUND:
/* This call happens when your app is coming back to the foreground.
Restore all your state here.
*/
return 0;
case SDL_APP_DIDENTERFOREGROUND:
/* Restart your loops here.
Your app is interactive and getting CPU again.
*/
return 0;
default:
/* No special processing, add it to the event queue */
return 1;
}
}
int main(int argc, char *argv[])
{
SDL_SetEventFilter(HandleAppEvents, NULL);
... run your main loop
return 0;
}
Notes -- Accelerometer as Joystick
==============================================================================
SDL for iPhone supports polling the built in accelerometer as a joystick device. For an example on how to do this, see the accelerometer.c in the demos directory.
The main thing to note when using the accelerometer with SDL is that while the iPhone natively reports accelerometer as floating point values in units of g-force, SDL_JoystickGetAxis() reports joystick values as signed integers. Hence, in order to convert between the two, some clamping and scaling is necessary on the part of the iPhone SDL joystick driver. To convert SDL_JoystickGetAxis() reported values BACK to units of g-force, simply multiply the values by SDL_IPHONE_MAX_GFORCE / 0x7FFF.
Notes -- OpenGL ES
==============================================================================
Your SDL application for iOS uses OpenGL ES for video by default.
OpenGL ES for iOS supports several display pixel formats, such as RGBA8 and RGB565, which provide a 32 bit and 16 bit color buffer respectively. By default, the implementation uses RGB565, but you may use RGBA8 by setting each color component to 8 bits in SDL_GL_SetAttribute().
If your application doesn't use OpenGL's depth buffer, you may find significant performance improvement by setting SDL_GL_DEPTH_SIZE to 0.
Finally, if your application completely redraws the screen each frame, you may find significant performance improvement by setting the attribute SDL_GL_RETAINED_BACKING to 0.
OpenGL ES on iOS doesn't use the traditional system-framebuffer setup provided in other operating systems. Special care must be taken because of this:
- The drawable Renderbuffer must be bound to the GL_RENDERBUFFER binding point when SDL_GL_SwapWindow() is called.
- The drawable Framebuffer Object must be bound while rendering to the screen and when SDL_GL_SwapWindow() is called.
- If multisample antialiasing (MSAA) is used and glReadPixels is used on the screen, the drawable framebuffer must be resolved to the MSAA resolve framebuffer (via glBlitFramebuffer or glResolveMultisampleFramebufferAPPLE), and the MSAA resolve framebuffer must be bound to the GL_READ_FRAMEBUFFER binding point, before glReadPixels is called.
The above objects can be obtained via SDL_GetWindowWMInfo() (in SDL_syswm.h).
Notes -- Keyboard
==============================================================================
The SDL keyboard API has been extended to support on-screen keyboards:
void SDL_StartTextInput()
-- enables text events and reveals the onscreen keyboard.
void SDL_StopTextInput()
-- disables text events and hides the onscreen keyboard.
SDL_bool SDL_IsTextInputActive()
-- returns whether or not text events are enabled (and the onscreen keyboard is visible)
Notes -- Mouse
==============================================================================
iOS now supports Bluetooth mice on iPad, but by default will provide the mouse input as touch. In order for SDL to see the real mouse events, you should set the key UIApplicationSupportsIndirectInputEvents to true in your Info.plist
Notes -- Reading and Writing files
==============================================================================
Each application installed on iPhone resides in a sandbox which includes its own Application Home directory. Your application may not access files outside this directory.
Once your application is installed its directory tree looks like:
MySDLApp Home/
MySDLApp.app
Documents/
Library/
Preferences/
tmp/
When your SDL based iPhone application starts up, it sets the working directory to the main bundle (MySDLApp Home/MySDLApp.app), where your application resources are stored. You cannot write to this directory. Instead, I advise you to write document files to "../Documents/" and preferences to "../Library/Preferences".
More information on this subject is available here:
http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/Introduction/Introduction.html
Notes -- xcFramework
==============================================================================
The SDL.xcodeproj file now includes a target to build SDL2.xcframework. An xcframework is a new (Xcode 11) uber-framework which can handle any combination of processor type and target OS platform.
In the past, iOS devices were always an ARM variant processor, and the simulator was always i386 or x86_64, and thus libraries could be combined into a single framework for both simulator and device. With the introduction of the Apple Silicon ARM-based machines, regular frameworks would collide as CPU type was no longer sufficient to differentiate the platform. So Apple created the new xcframework library package.
The xcframework target builds into a Products directory alongside the SDL.xcodeproj file, as SDL2.xcframework. This can be brought in to any iOS project and will function properly for both simulator and device, no matter their CPUs. Note that Intel Macs cannot cross-compile for Apple Silicon Macs. If you need AS compatibility, perform this build on an Apple Silicon Mac.
This target requires Xcode 11 or later. The target will simply fail to build if attempted on older Xcodes.
In addition, on Apple platforms, main() cannot be in a dynamically loaded library. This means that iOS apps which used the statically-linked libSDL2.lib and now link with the xcframwork will need to define their own main() to call SDL_UIKitRunApp(), like this:
#ifndef SDL_MAIN_HANDLED
#ifdef main
#undef main
#endif
int
main(int argc, char *argv[])
{
return SDL_UIKitRunApp(argc, argv, SDL_main);
}
#endif /* !SDL_MAIN_HANDLED */
Using an xcFramework is similar to using a regular framework. However, issues have been seen with the build system not seeing the headers in the xcFramework. To remedy this, add the path to the xcFramework in your app's target ==> Build Settings ==> Framework Search Paths and mark it recursive (this is critical). Also critical is to remove "*.framework" from Build Settings ==> Sub-Directories to Exclude in Recursive Searches. Clean the build folder, and on your next build the build system should be able to see any of these in your code, as expected:
#include "SDL_main.h"
#include <SDL.h>
#include <SDL_main.h>
Notes -- iPhone SDL limitations
==============================================================================
Windows:
Full-size, single window applications only. You cannot create multi-window SDL applications for iPhone OS. The application window will fill the display, though you have the option of turning on or off the menu-bar (pass SDL_CreateWindow() the flag SDL_WINDOW_BORDERLESS).
Textures:
The optimal texture formats on iOS are SDL_PIXELFORMAT_ABGR8888, SDL_PIXELFORMAT_ABGR8888, SDL_PIXELFORMAT_BGR888, and SDL_PIXELFORMAT_RGB24 pixel formats.
Loading Shared Objects:
This is disabled by default since it seems to break the terms of the iOS SDK agreement for iOS versions prior to iOS 8. It can be re-enabled in SDL_config_iphoneos.h.
Notes -- CoreBluetooth.framework
==============================================================================
SDL_JOYSTICK_HIDAPI is disabled by default. It can give you access to a lot
more game controller devices, but it requires permission from the user before
your app will be able to talk to the Bluetooth hardware. "Made For iOS"
branded controllers do not need this as we don't have to speak to them
directly with raw bluetooth, so many apps can live without this.
You'll need to link with CoreBluetooth.framework and add something like this
to your Info.plist:
<key>NSBluetoothPeripheralUsageDescription</key>
<string>MyApp would like to remain connected to nearby bluetooth Game Controllers and Game Pads even when you're not using the app.</string>
Game Center
==============================================================================
Game Center integration might require that you break up your main loop in order to yield control back to the system. In other words, instead of running an endless main loop, you run each frame in a callback function, using:
int SDL_iPhoneSetAnimationCallback(SDL_Window * window, int interval, void (*callback)(void*), void *callbackParam);
This will set up the given function to be called back on the animation callback, and then you have to return from main() to let the Cocoa event loop run.
e.g.
extern "C"
void ShowFrame(void*)
{
... do event handling, frame logic and rendering ...
}
int main(int argc, char *argv[])
{
... initialize game ...
#if __IPHONEOS__
// Initialize the Game Center for scoring and matchmaking
InitGameCenter();
// Set up the game to run in the window animation callback on iOS
// so that Game Center and so forth works correctly.
SDL_iPhoneSetAnimationCallback(window, 1, ShowFrame, NULL);
#else
while ( running ) {
ShowFrame(0);
DelayFrame();
}
#endif
return 0;
}
Deploying to older versions of iOS
==============================================================================
SDL supports deploying to older versions of iOS than are supported by the latest version of Xcode, all the way back to iOS 8.0
In order to do that you need to download an older version of Xcode:
https://developer.apple.com/download/more/?name=Xcode
Open the package contents of the older Xcode and your newer version of Xcode and copy over the folders in Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport
Then open the file Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/SDKSettings.plist and add the versions of iOS you want to deploy to the key Root/DefaultProperties/DEPLOYMENT_TARGET_SUGGESTED_VALUES
Open your project and set your deployment target to the desired version of iOS
Finally, remove GameController from the list of frameworks linked by your application and edit the build settings for "Other Linker Flags" and add -weak_framework GameController
KMSDRM on *BSD
==================================================
KMSDRM is supported on FreeBSD and OpenBSD. DragonFlyBSD works but requires being a root user. NetBSD isn't supported yet because the application will crash when creating the KMSDRM screen.
WSCONS support has been brought back, but only as an input backend. It will not be brought back as a video backend to ease maintenance.
OpenBSD note: Note that the video backend assumes that the user has read/write permissions to the /dev/drm* devices.
SDL2 WSCONS input backend features
===================================================
1. It is keymap-aware; it will work properly with different keymaps.
2. It has mouse support.
3. Accent input is supported.
4. Compose keys are supported.
5. AltGr and Meta Shift keys work as intended.
Partially working or no input on OpenBSD/NetBSD.
==================================================
The WSCONS input backend needs read/write access to the /dev/wskbd* devices, without which it will not work properly. /dev/wsmouse must also be read/write accessible, otherwise mouse input will not work.
Partially working or no input on FreeBSD.
==================================================
The evdev devices are only accessible to the root user by default. Edit devfs rules to allow access to such devices. The /dev/kbd* devices are also only accessible to the root user by default. Edit devfs rules to allow access to such devices.
Linux
================================================================================
By default SDL will only link against glibc, the rest of the features will be
enabled dynamically at runtime depending on the available features on the target
system. So, for example if you built SDL with XRandR support and the target
system does not have the XRandR libraries installed, it will be disabled
at runtime, and you won't get a missing library error, at least with the
default configuration parameters.
Build Dependencies
--------------------------------------------------------------------------------
Ubuntu 18.04, all available features enabled:
sudo apt-get install build-essential git make autoconf automake libtool \
pkg-config cmake ninja-build gnome-desktop-testing libasound2-dev libpulse-dev \
libaudio-dev libjack-dev libsndio-dev libsamplerate0-dev libx11-dev libxext-dev \
libxrandr-dev libxcursor-dev libxfixes-dev libxi-dev libxss-dev libwayland-dev \
libxkbcommon-dev libdrm-dev libgbm-dev libgl1-mesa-dev libgles2-mesa-dev \
libegl1-mesa-dev libdbus-1-dev libibus-1.0-dev libudev-dev fcitx-libs-dev
Ubuntu 22.04+ can also add `libpipewire-0.3-dev libdecor-0-dev` to that command line.
Fedora 35, all available features enabled:
sudo yum install gcc git-core make cmake autoconf automake libtool \
alsa-lib-devel pulseaudio-libs-devel nas-devel pipewire-devel \
libX11-devel libXext-devel libXrandr-devel libXcursor-devel libXfixes-devel \
libXi-devel libXScrnSaver-devel dbus-devel ibus-devel fcitx-devel \
systemd-devel mesa-libGL-devel libxkbcommon-devel mesa-libGLES-devel \
mesa-libEGL-devel vulkan-devel wayland-devel wayland-protocols-devel \
libdrm-devel mesa-libgbm-devel libusb-devel libdecor-devel \
libsamplerate-devel pipewire-jack-audio-connection-kit-devel \
NOTES:
- This includes all the audio targets except arts and esd, because Ubuntu
(and/or Debian) pulled their packages, but in theory SDL still supports them.
The sndio audio target is also unavailable on Fedora.
- libsamplerate0-dev lets SDL optionally link to libresamplerate at runtime
for higher-quality audio resampling. SDL will work without it if the library
is missing, so it's safe to build in support even if the end user doesn't
have this library installed.
- DirectFB isn't included because the configure script (currently) fails to find
it at all. You can do "sudo apt-get install libdirectfb-dev" and fix the
configure script to include DirectFB support. Send patches. :)
Joystick does not work
--------------------------------------------------------------------------------
If you compiled or are using a version of SDL with udev support (and you should!)
there's a few issues that may cause SDL to fail to detect your joystick. To
debug this, start by installing the evtest utility. On Ubuntu/Debian:
sudo apt-get install evtest
Then run:
sudo evtest
You'll hopefully see your joystick listed along with a name like "/dev/input/eventXX"
Now run:
cat /dev/input/event/XX
If you get a permission error, you need to set a udev rule to change the mode of
your device (see below)
Also, try:
sudo udevadm info --query=all --name=input/eventXX
If you see a line stating ID_INPUT_JOYSTICK=1, great, if you don't see it,
you need to set up an udev rule to force this variable.
A combined rule for the Saitek Pro Flight Rudder Pedals to fix both issues looks
like:
SUBSYSTEM=="input", ATTRS{idProduct}=="0763", ATTRS{idVendor}=="06a3", MODE="0666", ENV{ID_INPUT_JOYSTICK}="1"
SUBSYSTEM=="input", ATTRS{idProduct}=="0764", ATTRS{idVendor}=="06a3", MODE="0666", ENV{ID_INPUT_JOYSTICK}="1"
You can set up similar rules for your device by changing the values listed in
idProduct and idVendor. To obtain these values, try:
sudo udevadm info -a --name=input/eventXX | grep idVendor
sudo udevadm info -a --name=input/eventXX | grep idProduct
If multiple values come up for each of these, the one you want is the first one of each.
On other systems which ship with an older udev (such as CentOS), you may need
to set up a rule such as:
SUBSYSTEM=="input", ENV{ID_CLASS}=="joystick", ENV{ID_INPUT_JOYSTICK}="1"
# Mac OS X (aka macOS).
These instructions are for people using Apple's Mac OS X (pronounced
"ten"), which in newer versions is just referred to as "macOS".
From the developer's point of view, macOS is a sort of hybrid Mac and
Unix system, and you have the option of using either traditional
command line tools or Apple's IDE Xcode.
# Command Line Build
To build SDL using the command line, use the standard configure and make
process:
```bash
mkdir build
cd build
../configure
make
sudo make install
```
CMake is also known to work, although it continues to be a work in progress:
```bash
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make
sudo make install
```
You can also build SDL as a Universal library (a single binary for both
64-bit Intel and ARM architectures), by using the build-scripts/clang-fat.sh
script.
```bash
mkdir build
cd build
CC=$PWD/../build-scripts/clang-fat.sh ../configure
make
sudo make install
```
This script builds SDL with 10.9 ABI compatibility on 64-bit Intel and 11.0
ABI compatibility on ARM64 architectures. For best compatibility you
should compile your application the same way.
Please note that building SDL requires at least Xcode 6 and the 10.9 SDK.
PowerPC support for macOS has been officially dropped as of SDL 2.0.2.
32-bit Intel and macOS 10.8 runtime support has been officially dropped as
of SDL 2.24.0.
To use the library once it's built, you essential have two possibilities:
use the traditional autoconf/automake/make method, or use Xcode.
# Caveats for using SDL with Mac OS X
If you register your own NSApplicationDelegate (using [NSApp setDelegate:]),
SDL will not register its own. This means that SDL will not terminate using
SDL_Quit if it receives a termination request, it will terminate like a
normal app, and it will not send a SDL_DROPFILE when you request to open a
file with the app. To solve these issues, put the following code in your
NSApplicationDelegate implementation:
```objc
- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
{
if (SDL_GetEventState(SDL_QUIT) == SDL_ENABLE) {
SDL_Event event;
event.type = SDL_QUIT;
SDL_PushEvent(&event);
}
return NSTerminateCancel;
}
- (BOOL)application:(NSApplication *)theApplication openFile:(NSString *)filename
{
if (SDL_GetEventState(SDL_DROPFILE) == SDL_ENABLE) {
SDL_Event event;
event.type = SDL_DROPFILE;
event.drop.file = SDL_strdup([filename UTF8String]);
return (SDL_PushEvent(&event) > 0);
}
return NO;
}
```
# Using the Simple DirectMedia Layer with a traditional Makefile
An existing autoconf/automake build system for your SDL app has good chances
to work almost unchanged on macOS. However, to produce a "real" Mac binary
that you can distribute to users, you need to put the generated binary into a
so called "bundle", which is basically a fancy folder with a name like
"MyCoolGame.app".
To get this build automatically, add something like the following rule to
your Makefile.am:
```make
bundle_contents = APP_NAME.app/Contents
APP_NAME_bundle: EXE_NAME
mkdir -p $(bundle_contents)/MacOS
mkdir -p $(bundle_contents)/Resources
echo "APPL????" > $(bundle_contents)/PkgInfo
$(INSTALL_PROGRAM) $< $(bundle_contents)/MacOS/
```
You should replace `EXE_NAME` with the name of the executable. `APP_NAME` is
what will be visible to the user in the Finder. Usually it will be the same
as `EXE_NAME` but capitalized. E.g. if `EXE_NAME` is "testgame" then `APP_NAME`
usually is "TestGame". You might also want to use `@PACKAGE@` to use the
package name as specified in your configure.ac file.
If your project builds more than one application, you will have to do a bit
more. For each of your target applications, you need a separate rule.
If you want the created bundles to be installed, you may want to add this
rule to your Makefile.am:
```make
install-exec-hook: APP_NAME_bundle
rm -rf $(DESTDIR)$(prefix)/Applications/APP_NAME.app
mkdir -p $(DESTDIR)$(prefix)/Applications/
cp -r $< /$(DESTDIR)$(prefix)Applications/
```
This rule takes the Bundle created by the rule from step 3 and installs them
into "$(DESTDIR)$(prefix)/Applications/".
Again, if you want to install multiple applications, you will have to augment
the make rule accordingly.
But beware! That is only part of the story! With the above, you end up with
a barebones .app bundle, which is double-clickable from the Finder. But
there are some more things you should do before shipping your product...
1. The bundle right now probably is dynamically linked against SDL. That
means that when you copy it to another computer, *it will not run*,
unless you also install SDL on that other computer. A good solution
for this dilemma is to static link against SDL. On OS X, you can
achieve that by linking against the libraries listed by
```bash
sdl-config --static-libs
```
instead of those listed by
```bash
sdl-config --libs
```
Depending on how exactly SDL is integrated into your build systems, the
way to achieve that varies, so I won't describe it here in detail
2. Add an 'Info.plist' to your application. That is a special XML file which
contains some meta-information about your application (like some copyright
information, the version of your app, the name of an optional icon file,
and other things). Part of that information is displayed by the Finder
when you click on the .app, or if you look at the "Get Info" window.
More information about Info.plist files can be found on Apple's homepage.
As a final remark, let me add that I use some of the techniques (and some
variations of them) in [Exult](https://github.com/exult/exult) and
[ScummVM](https://github.com/scummvm/scummvm); both are available in source on
the net, so feel free to take a peek at them for inspiration!
# Using the Simple DirectMedia Layer with Xcode
These instructions are for using Apple's Xcode IDE to build SDL applications.
## First steps
The first thing to do is to unpack the Xcode.tar.gz archive in the
top level SDL directory (where the Xcode.tar.gz archive resides).
Because Stuffit Expander will unpack the archive into a subdirectory,
you should unpack the archive manually from the command line:
```bash
cd [path_to_SDL_source]
tar zxf Xcode.tar.gz
```
This will create a new folder called Xcode, which you can browse
normally from the Finder.
## Building the Framework
The SDL Library is packaged as a framework bundle, an organized
relocatable folder hierarchy of executable code, interface headers,
and additional resources. For practical purposes, you can think of a
framework as a more user and system-friendly shared library, whose library
file behaves more or less like a standard UNIX shared library.
To build the framework, simply open the framework project and build it.
By default, the framework bundle "SDL.framework" is installed in
/Library/Frameworks. Therefore, the testers and project stationary expect
it to be located there. However, it will function the same in any of the
following locations:
* ~/Library/Frameworks
* /Local/Library/Frameworks
* /System/Library/Frameworks
## Build Options
There are two "Build Styles" (See the "Targets" tab) for SDL.
"Deployment" should be used if you aren't tweaking the SDL library.
"Development" should be used to debug SDL apps or the library itself.
## Building the Testers
Open the SDLTest project and build away!
## Using the Project Stationary
Copy the stationary to the indicated folders to access it from
the "New Project" and "Add target" menus. What could be easier?
## Setting up a new project by hand
Some of you won't want to use the Stationary so I'll give some tips:
(this is accurate as of Xcode 12.5.)
* Click "File" -> "New" -> "Project...
* Choose "macOS" and then "App" from the "Application" section.
* Fill out the options in the next window. User interface is "XIB" and
Language is "Objective-C".
* Remove "main.m" from your project
* Remove "MainMenu.xib" from your project
* Remove "AppDelegates.*" from your project
* Add "\$(HOME)/Library/Frameworks/SDL.framework/Headers" to include path
* Add "\$(HOME)/Library/Frameworks" to the frameworks search path
* Add "-framework SDL -framework Foundation -framework AppKit" to "OTHER_LDFLAGS"
* Add your files
* Clean and build
## Building from command line
Use `xcode-build` in the same directory as your .pbxproj file
## Running your app
You can send command line args to your app by either invoking it from
the command line (in *.app/Contents/MacOS) or by entering them in the
Executables" panel of the target settings.
# Implementation Notes
Some things that may be of interest about how it all works...
## Working directory
In SDL 1.2, the working directory of your SDL app is by default set to its
parent, but this is no longer the case in SDL 2.0. SDL2 does change the
working directory, which means it'll be whatever the command line prompt
that launched the program was using, or if launched by double-clicking in
the finger, it will be "/", the _root of the filesystem_. Plan accordingly!
You can use SDL_GetBasePath() to find where the program is running from and
chdir() there directly.
## You have a Cocoa App!
Your SDL app is essentially a Cocoa application. When your app
starts up and the libraries finish loading, a Cocoa procedure is called,
which sets up the working directory and calls your main() method.
You are free to modify your Cocoa app with generally no consequence
to SDL. You cannot, however, easily change the SDL window itself.
Functionality may be added in the future to help this.
# Bug reports
Bugs are tracked at [the GitHub issue tracker](https://github.com/libsdl-org/SDL/issues/).
Please feel free to report bugs there!
# Nintendo 3DS
SDL port for the Nintendo 3DS [Homebrew toolchain](https://devkitpro.org/) contributed by:
- [Pierre Wendling](https://github.com/FtZPetruska)
Credits to:
- The awesome people who ported SDL to other homebrew platforms.
- The Devkitpro team for making all the tools necessary to achieve this.
## Building
To build for the Nintendo 3DS, make sure you have devkitARM and cmake installed and run:
```bash
cmake -S. -Bbuild -DCMAKE_TOOLCHAIN_FILE="$DEVKITPRO/cmake/3DS.cmake" -DCMAKE_BUILD_TYPE=Release
cmake --build build
cmake --install build
```
## Notes
- Currently only software rendering is supported.
- SDL2main should be used to ensure ROMFS is enabled.
- By default, the extra L2 cache and higher clock speeds of the New 2/3DS lineup are enabled. If you wish to turn it off, use `osSetSpeedupEnable(false)` in your main function.
- `SDL_GetBasePath` returns the romfs root instead of the executable's directory.
- The Nintendo 3DS uses a cooperative threading model on a single core, meaning a thread will never yield unless done manually through the `SDL_Delay` functions, or blocking waits (`SDL_LockMutex`, `SDL_SemWait`, `SDL_CondWait`, `SDL_WaitThread`). To avoid starving other threads, `SDL_SemTryWait` and `SDL_SemWaitTimeout` will yield if they fail to acquire the semaphore, see https://github.com/libsdl-org/SDL/pull/6776 for more information.
Native Client
================================================================================
Requirements:
* Native Client SDK (https://developer.chrome.com/native-client),
(tested with Pepper version 33 or higher).
The SDL backend for Chrome's Native Client has been tested only with the PNaCl
toolchain, which generates binaries designed to run on ARM and x86_32/64
platforms. This does not mean it won't work with the other toolchains!
================================================================================
Building SDL for NaCl
================================================================================
Set up the right environment variables (see naclbuild.sh), then configure SDL with:
configure --host=pnacl --prefix some/install/destination
Then "make".
As an example of how to create a deployable app a Makefile project is provided
in test/nacl/Makefile, which includes some monkey patching of the common.mk file
provided by NaCl, without which linking properly to SDL won't work (the search
path can't be modified externally, so the linker won't find SDL's binaries unless
you dump them into the SDK path, which is inconvenient).
Also provided in test/nacl is the required support file, such as index.html,
manifest.json, etc.
SDL apps for NaCl run on a worker thread using the ppapi_simple infrastructure.
This allows for blocking calls on all the relevant systems (OpenGL ES, filesystem),
hiding the asynchronous nature of the browser behind the scenes...which is not the
same as making it disappear!
================================================================================
Running tests
================================================================================
Due to the nature of NaCl programs, building and running SDL tests is not as
straightforward as one would hope. The script naclbuild.sh in build-scripts
automates the process and should serve as a guide for users of SDL trying to build
their own applications.
Basic usage:
./naclbuild.sh path/to/pepper/toolchain (i.e. ~/naclsdk/pepper_35)
This will build testgles2.c by default.
If you want to build a different test, for example testrendercopyex.c:
SOURCES=~/sdl/SDL/test/testrendercopyex.c ./naclbuild.sh ~/naclsdk/pepper_35
Once the build finishes, you have to serve the contents with a web server (the
script will give you instructions on how to do that with Python).
================================================================================
RWops and nacl_io
================================================================================
SDL_RWops work transparently with nacl_io. Two functions control the mount points:
int mount(const char* source, const char* target,
const char* filesystemtype,
unsigned long mountflags, const void *data);
int umount(const char *target);
For convenience, SDL will by default mount an httpfs tree at / before calling
the app's main function. Such setting can be overridden by calling:
umount("/");
And then mounting a different filesystem at /
It's important to consider that the asynchronous nature of file operations on a
browser is hidden from the application, effectively providing the developer with
a set of blocking file operations just like you get in a regular desktop
environment, which eases the job of porting to Native Client, but also introduces
a set of challenges of its own, in particular when big file sizes and slow
connections are involved.
For more information on how nacl_io and mount points work, see:
https://developer.chrome.com/native-client/devguide/coding/nacl_io
https://src.chromium.org/chrome/trunk/src/native_client_sdk/src/libraries/nacl_io/nacl_io.h
To be able to save into the directory "/save/" (like backup of game) :
mount("", "/save", "html5fs", 0, "type=PERSISTENT");
And add to manifest.json :
"permissions": [
"unlimitedStorage"
]
================================================================================
TODO - Known Issues
================================================================================
* Testing of all systems with a real application (something other than SDL's tests)
* Key events don't seem to work properly
Nokia N-Gage
============
SDL2 port for Symbian S60v1 and v2 with a main focus on the Nokia N-Gage
(Classic and QD) by [Michael Fitzmayer](https://github.com/mupfdev).
Compiling
---------
SDL is part of the [N-Gage SDK.](https://github.com/ngagesdk) project.
The library is included in the
[toolchain](https://github.com/ngagesdk/ngage-toolchain) as a
sub-module.
A complete example project based on SDL2 can be found in the GitHub
account of the SDK: [Wordle](https://github.com/ngagesdk/wordle).
Current level of implementation
-------------------------------
The video driver currently provides full screen video support with
keyboard input.
At the moment only the software renderer works.
Audio is not yet implemented.
Acknowledgements
----------------
Thanks to Hannu Viitala, Kimmo Kinnunen and Markus Mertama for the
valuable insight into Symbian programming. Without the SDL 1.2 port
which was specially developed for CDoom (Doom for the Nokia 9210), this
adaptation would not have been possible.
I would like to thank my friends
[Razvan](https://twitter.com/bewarerazvan) and [Dan
Whelan](https://danwhelan.ie/), for their continuous support. Without
you and the [N-Gage community](https://discord.gg/dbUzqJ26vs), I would
have lost my patience long ago.
Last but not least, I would like to thank the development team of
[EKA2L1](https://12z1.com/) (an experimental Symbian OS emulator). Your
patience and support in troubleshooting helped me a lot.
Simple DirectMedia Layer 2 for OS/2 & eComStation
================================================================================
SDL port for OS/2, authored by Andrey Vasilkin <digi@os2.snc.ru>, 2016
OpenGL not supported by this port.
Additional optional environment variables:
SDL_AUDIO_SHARE
Values: 0 or 1, default is 0
Initializes the device as shareable or exclusively acquired.
SDL_VIDEODRIVER
Values: DIVE or VMAN, default is DIVE
Use video subsystem: Direct interface video extensions (DIVE) or
Video Manager (VMAN).
You may significantly increase video output speed with OS4 kernel and patched
files vman.dll and dive.dll or with latest versions of ACPI support and video
driver Panorama.
Latest versions of OS/4 kernel:
http://gus.biysk.ru/os4/
(Info: https://www.os2world.com/wiki/index.php/Phoenix_OS/4)
Patched files vman.dll and dive.dll:
http://gus.biysk.ru/os4/test/pached_dll/PATCHED_DLL.RAR
Compiling:
----------
Open Watcom 1.9 or newer is tested. For the new Open Watcom V2 fork, see:
https://github.com/open-watcom/ and https://open-watcom.github.io
WATCOM environment variable must to be set to the Open Watcom install
directory. To compile, run: wmake -f Makefile.os2
Installing:
-----------
- eComStation:
If you have previously installed SDL2, make a Backup copy of SDL2.dll
located in D:\ecs\dll (where D: is disk on which installed eComStation).
Stop all programs running with SDL2. Copy SDL2.dll to D:\ecs\dll
- OS/2:
Copy SDL2.dll to any directory on your LIBPATH. If you have a previous
version installed, close all SDL2 applications before replacing the old
copy. Also make sure that any other older versions of DLLs are removed
from your system.
Joysticks in SDL2:
------------------
The joystick code in SDL2 is a direct forward-port from the SDL-1.2 version.
Here is the original documentation from SDL-1.2:
The Joystick detection only works for standard joysticks (2 buttons, 2 axes
and the like). Therefore, if you use a non-standard joystick, you should
specify its features in the SDL_OS2_JOYSTICK environment variable in a batch
file or CONFIG.SYS, so SDL applications can provide full capability to your
device. The syntax is:
SET SDL_OS2_JOYSTICK=[JOYSTICK_NAME] [AXES] [BUTTONS] [HATS] [BALLS]
So, it you have a Gravis GamePad with 4 axes, 2 buttons, 2 hats and 0 balls,
the line should be:
SET SDL_OS2_JOYSTICK=Gravis_GamePad 4 2 2 0
If you want to add spaces in your joystick name, just surround it with
quotes or double-quotes:
SET SDL_OS2_JOYSTICK='Gravis GamePad' 4 2 2 0
or
SET SDL_OS2_JOYSTICK="Gravis GamePad" 4 2 2 0
Note however that Balls and Hats are not supported under OS/2, and the
value will be ignored... but it is wise to define these correctly because
in the future those can be supported.
Also the number of buttons is limited to 2 when using two joysticks,
4 when using one joystick with 4 axes, 6 when using a joystick with 3 axes
and 8 when using a joystick with 2 axes. Notice however these are limitations
of the Joystick Port hardware, not OS/2.
Pandora
=====================================================================
( http://openpandora.org/ )
- A pandora specific video driver was written to allow SDL 2.0 with OpenGL ES
support to work on the pandora under the framebuffer. This driver do not have
input support for now, so if you use it you will have to add your own control code.
The video driver name is "pandora" so if you have problem running it from
the framebuffer, try to set the following variable before starting your application :
"export SDL_VIDEODRIVER=pandora"
- OpenGL ES support was added to the x11 driver, so it's working like the normal
x11 driver one with OpenGLX support, with SDL input event's etc..
David Carré (Cpasjuste)
cpasjuste@gmail.com
Platforms
=========
We maintain the list of supported platforms on our wiki now, and how to
build and install SDL for those platforms:
https://wiki.libsdl.org/Installation