From c6cfc8f7f258f5f1a505e4f92198fd6bd3fbbc90 Mon Sep 17 00:00:00 2001
From: David Gow <[EMAIL REDACTED]>
Date: Sun, 26 Sep 2021 16:00:31 +0800
Subject: [PATCH] Support SDL12COMPAT_SYNC_TO_VBLANK for OpenGL apps
For non-OpenGL applications, the SDL12COMPAT_SYNC_TO_VBLANK environment
variable could be used to enable/disable VSync. For OpenGL applications,
this was always able to be controlled by the application, using the
SDL_GL_SWAP_CONTROL attribute. However, some old games do not provide a
simple mechanism for configuring VSync (and so either don't set
SDL_GL_SWAP_CONTROL, or always set it to an undesirable value).
Allow the SDL12COMPAT_SYNC_TO_VBLANK environment variable to override
the SDL_GL_SWAP_CONTROL attribute for OpenGL windows. The existing
behaviour remains if SDL12COMPAT_SYNC_TO_VBLANK is not set.
(Also remove a FIXME() which was obsolete.)
---
src/SDL12_compat.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index d55f192..6bde98d 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -4408,6 +4408,7 @@ SDL_SetVideoMode(int width, int height, int bpp, Uint32 flags12)
}
if (flags12 & SDL12_OPENGL) {
+ const char *vsync_env = SDL20_getenv("SDL12COMPAT_SYNC_TO_VBLANK");
SDL_assert(!VideoTexture20); /* either a new window or we destroyed all this */
SDL_assert(!VideoRenderer20);
FIXME("Should we force a compatibility context here?");
@@ -4456,7 +4457,11 @@ SDL_SetVideoMode(int width, int height, int bpp, Uint32 flags12)
VideoSurface12->flags |= SDL12_OPENGLBLIT;
}
- SDL20_GL_SetSwapInterval(SwapInterval);
+ if (vsync_env) {
+ SDL20_GL_SetSwapInterval(SDL20_atoi(vsync_env));
+ } else {
+ SDL20_GL_SetSwapInterval(SwapInterval);
+ }
} else {
/* always use a renderer for non-OpenGL windows. */
@@ -5728,7 +5733,6 @@ SDL_GL_SetAttribute(SDL12_GLattr attr, int value)
/* swap control was moved out of this API, everything else lines up. */
if (attr == SDL12_GL_SWAP_CONTROL) {
SwapInterval = value;
- FIXME("Actually set swap interval somewhere");
return 0;
}
else if (attr == SDL12_GL_MULTISAMPLESAMPLES) {