Linedef action 5 "Camera Scanner" Falsly blamed for causing camera issues

After the Autumn OLDC of 2020 SRB2 received an update in which all use of the camera scanner produces a console message that the action is depreciated. Hearing that this action was broken, I wanted more details. Those details about how it was broken were that a level from this oldc called "Azlant Ruins" was causing camera issues with this action and that this action affected Cvars in ways that saved them.

Upon learning this I decided to investigate, and I found some results that should clear the name of this action.

First. How the action works can be seen on both the wiki and this gitlab. https://wiki.srb2.org/wiki/Linedef_type_5 https://git.do.srb2.org/STJr/SRB2/blob/next/doc/specials.html

      <h3><a name="l5"></a>5 - Camera Scanner</h3>
      <p>Modifies camera position while the player is in the target sector. The floor and
      ceiling of the control sector and the angle of the control linedef are the values for
      CAM_HEIGHT, CAM_DIST, and CAM_ROTATE, respectively. Camera position is reset when the
      player steps outside the sector.</p>

A key part to notice is where it says Camera position is reset when the player steps outside the sector. This plays a key part later on.

Second, the way the map was set up involved the use of a script to stop the camera from moving. the Script would be triggered in level calling the console command setting cam_speed to 0 when the level was done with that script, it "reset" the camespeed to the wrong speed

When I quit the game with the scanner active, including via Alt-F4, the Cvars it affected were not saved, but the one affected by the script was.

The Same result happened with just quitting to the title with only the cam_speed Cvar being the only one actually written to. https://imgur.com/Q9aSLX3

In conclusion, The only real camera issue was the one caused by the script writing the CAM_SPEED cvar by using the console command and not the camera scanner action itself.

If an example wad is necessary to prove my claim, I will provide one.

Edit, More details: Apparently the values that are supposedly being written are not able to be seen by the console commands. (this bottom image was taken with cam_speed at 0.5)

changed the description

As far as I'm aware with this linedef special, the following happens:

• you enter a sector tagged with the special
• the special's thinker then alters the values of the consvars cam_height, cam_dist and cam_rotate (or their player 2 versions, if player 2 is in there), but it saves copies of all three (or six) in some temporary variables
• when you leave the sector, all the consvars are restored to their old values, and the temporary variables are restored to their defaults of "-42", so it's as if the special never did anything at all
• however, it is possible for it to mess up your config if you exit the game while still under effect of a scanner, this bug has been known since a while back. However, since not many people seem to use the camera scanner effect at all and may not know how it works, I think some may have mistakely thought the special always permanently alters your config regardless? I can't make sense of this confusion otherwise tbh

And yes, the scanner never did modify cam_speed to begin with. That's definitely all the script's fault clearly.

I'm not to sure about the mess up as I went ahead and tested that too.

None of the following screenshots are the result of closing the game while in the camera scanner sector

The Green flower picture (with tails' head right up against the camera lens) showed what actually happened, but if the other cvars were saved, then something like this should have happened after cam_speed was restored:

While cam_speed is left as zero, it will instead produce this result (another test screen)

once again, give the camera some speed and the other cvars will move the camera

Alright, with Glaber's assistance I've figured out what's going on, and it's pretty confusing.

Back when the decision was made to deprecate the camera scanner, it did cause problems: It affects the camera by directly changing the values of the console variables cv_cam_dist, cv_cam_height and cv_cam_rotate. The former two were saved to the config, so if you quit the game while affected a by camera scanner, it would mess up the values in your config.

It turns out that !647 (merged) inadvertently fixed this: cv_cam_dist and cv_cam_height had their console names changed to cam_curdist and cam_curheight and are no longer directly saved to the config. Instead cam_dist and cam_height are now the console names of the new variables cv_cam_savedist and cv_cam_saveheight. As a result of this (highly confusing, I must say!) rename, the camera scanner can no longer write to the config.

That doesn't mean the camera scanner isn't still hacky as hell! It's just a terrifying case of two bad coding practices accidentally canceling each other out.

Proposed fix:

• Rename cv_cam_dist and cv_cam_height to cv_cam_curdist and cv_cam_curheight to prevent confusion.
• Either leave the camera scanner deprecated or refactor it properly.