From 0894547d1a54e1107a5a32034d96693a9e29cabc Mon Sep 17 00:00:00 2001
From: Hannu Hanhi <hhanhipublic@gmail.com>
Date: Fri, 17 Sep 2021 22:19:51 +0300
Subject: [PATCH] Use GL_LUMINANCE8 for 3d palette lookup texture on OpenGL
versions older than 3.0
Fixes white screen when the GL_R8 format is not available
---
src/hardware/r_opengl/r_opengl.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/src/hardware/r_opengl/r_opengl.c b/src/hardware/r_opengl/r_opengl.c
index 3f77be1ec0..7c9a37131f 100644
--- a/src/hardware/r_opengl/r_opengl.c
+++ b/src/hardware/r_opengl/r_opengl.c
@@ -3262,13 +3262,26 @@ EXPORT void HWRAPI(DrawScreenFinalTexture)(int tex, int width, int height)
EXPORT void HWRAPI(SetPaletteLookup)(UINT8 *lut)
{
+ GLenum internalFormat;
+ if (gl_version[0] == '1' || gl_version[0] == '2')
+ {
+ // if the OpenGL version is below 3.0, then the GL_R8 format may not be available.
+ // so use GL_LUMINANCE8 instead to get a single component 8-bit format
+ // (it is possible to have access to shaders even in some OpenGL 1.x systems,
+ // so palette rendering can still possibly be achieved there)
+ internalFormat = GL_LUMINANCE8;
+ }
+ else
+ {
+ internalFormat = GL_R8;
+ }
if (!paletteLookupTex)
pglGenTextures(1, &paletteLookupTex);
pglActiveTexture(GL_TEXTURE1);
pglBindTexture(GL_TEXTURE_3D, paletteLookupTex);
pglTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
pglTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
- pglTexImage3D(GL_TEXTURE_3D, 0, GL_R8, HWR_PALETTE_LUT_SIZE, HWR_PALETTE_LUT_SIZE, HWR_PALETTE_LUT_SIZE,
+ pglTexImage3D(GL_TEXTURE_3D, 0, internalFormat, HWR_PALETTE_LUT_SIZE, HWR_PALETTE_LUT_SIZE, HWR_PALETTE_LUT_SIZE,
0, GL_RED, GL_UNSIGNED_BYTE, lut);
pglActiveTexture(GL_TEXTURE0);
}
--
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