video: Apparently 24-bit video is intended to be BGR24 pixels.

icculus · icculus · commit 56119b273d54 · 2022-09-01T20:12:59.000-04:00
We had changed this in 9403529, from RGB24 to RGB888, which fixed Schismtracker, but this isn't actually correct either, I guess. Using BGR24 fixes "Powder", which apparently _needs_ a 24-bit packed format, and Schismtracker still works correctly, so I think we're good here now. I hope. Fixes #199.
diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
@@ -5693,7 +5693,7 @@ SDL_SetVideoMode(int width, int height, int bpp, Uint32 flags12)
     switch (bpp) {
         case  8: appfmt = SDL_PIXELFORMAT_INDEX8; break;
         case 16: appfmt = SDL_PIXELFORMAT_RGB565; break;
-        case 24: appfmt = SDL_PIXELFORMAT_RGB888; break;
+        case 24: appfmt = SDL_PIXELFORMAT_BGR24; break;
         case 32: appfmt = SDL_PIXELFORMAT_XRGB8888; break;
         default: SDL20_SetError("Unsupported bits-per-pixel"); return NULL;
     }

Original file line number	Diff line number	Diff line change
`@@ -5693,7 +5693,7 @@ SDL_SetVideoMode(int width, int height, int bpp, Uint32 flags12)`
`5693`	`5693`	`switch (bpp) {`
`5694`	`5694`	`case 8: appfmt = SDL_PIXELFORMAT_INDEX8; break;`
`5695`	`5695`	`case 16: appfmt = SDL_PIXELFORMAT_RGB565; break;`
`5696`		`- case 24: appfmt = SDL_PIXELFORMAT_RGB888; break;`
	`5696`	`+ case 24: appfmt = SDL_PIXELFORMAT_BGR24; break;`
`5697`	`5697`	`case 32: appfmt = SDL_PIXELFORMAT_XRGB8888; break;`
`5698`	`5698`	`default: SDL20_SetError("Unsupported bits-per-pixel"); return NULL;`
`5699`	`5699`	`}`