From 1fd66cc890a4cc16d23e34982f6600d403e7a74f Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Wed, 16 Nov 2022 10:15:21 -0500
Subject: [PATCH] Revert "cocoa: Backed out CVDisplayLink code for macOS
vsync."
This reverts commit 04b50f6c6bef67b744b192c78775771b51ff2141.
It turns out OpenGL vsync has broken again in macOS 12, so
we're reintroducing our CVDisplayLink code to deal with it,
again.
Reference Issue #4918.
---
src/video/cocoa/SDL_cocoaopengl.h | 7 ++-
src/video/cocoa/SDL_cocoaopengl.m | 96 +++++++++++++++++++++++--------
2 files changed, 79 insertions(+), 24 deletions(-)
diff --git a/src/video/cocoa/SDL_cocoaopengl.h b/src/video/cocoa/SDL_cocoaopengl.h
index 0f9b1c7f0a92..a483ac08a002 100644
--- a/src/video/cocoa/SDL_cocoaopengl.h
+++ b/src/video/cocoa/SDL_cocoaopengl.h
@@ -42,6 +42,11 @@ struct SDL_GLDriverData
@interface SDLOpenGLContext : NSOpenGLContext {
SDL_atomic_t dirty;
SDL_Window *window;
+ CVDisplayLinkRef displayLink;
+ @public SDL_mutex *swapIntervalMutex;
+ @public SDL_cond *swapIntervalCond;
+ @public SDL_atomic_t swapIntervalSetting;
+ @public SDL_atomic_t swapIntervalsPassed;
}
- (id)initWithFormat:(NSOpenGLPixelFormat *)format
@@ -51,7 +56,7 @@ struct SDL_GLDriverData
- (void)setWindow:(SDL_Window *)window;
- (SDL_Window*)window;
- (void)explicitUpdate;
-
+- (void)dealloc;
@end
/* OpenGL functions */
diff --git a/src/video/cocoa/SDL_cocoaopengl.m b/src/video/cocoa/SDL_cocoaopengl.m
index 8aab0c4cb64e..af17ae228fa9 100644
--- a/src/video/cocoa/SDL_cocoaopengl.m
+++ b/src/video/cocoa/SDL_cocoaopengl.m
@@ -52,6 +52,23 @@
SDL_opengl_async_dispatch = SDL_GetStringBoolean(hint, SDL_FALSE);
}
+static CVReturn
+DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp* now, const CVTimeStamp* outputTime, CVOptionFlags flagsIn, CVOptionFlags* flagsOut, void* displayLinkContext)
+{
+ SDLOpenGLContext *nscontext = (__bridge SDLOpenGLContext *) displayLinkContext;
+
+ /*printf("DISPLAY LINK! %u\n", (unsigned int) SDL_GetTicks()); */
+ const int setting = SDL_AtomicGet(&nscontext->swapIntervalSetting);
+ if (setting != 0) { /* nothing to do if vsync is disabled, don't even lock */
+ SDL_LockMutex(nscontext->swapIntervalMutex);
+ SDL_AtomicAdd(&nscontext->swapIntervalsPassed, 1);
+ SDL_CondSignal(nscontext->swapIntervalCond);
+ SDL_UnlockMutex(nscontext->swapIntervalMutex);
+ }
+
+ return kCVReturnSuccess;
+}
+
@implementation SDLOpenGLContext : NSOpenGLContext
- (id)initWithFormat:(NSOpenGLPixelFormat *)format
@@ -61,6 +78,19 @@ - (id)initWithFormat:(NSOpenGLPixelFormat *)format
if (self) {
SDL_AtomicSet(&self->dirty, 0);
self->window = NULL;
+ SDL_AtomicSet(&self->swapIntervalSetting, 0);
+ SDL_AtomicSet(&self->swapIntervalsPassed, 0);
+ self->swapIntervalCond = SDL_CreateCond();
+ self->swapIntervalMutex = SDL_CreateMutex();
+ if (!self->swapIntervalCond || !self->swapIntervalMutex) {
+ return nil;
+ }
+
+ /* !!! FIXME: check return values. */
+ CVDisplayLinkCreateWithActiveCGDisplays(&self->displayLink);
+ CVDisplayLinkSetOutputCallback(self->displayLink, &DisplayLinkCallback, (__bridge void * _Nullable) self);
+ CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(self->displayLink, [self CGLContextObj], [format CGLPixelFormatObj]);
+ CVDisplayLinkStart(displayLink);
}
SDL_AddHintCallback(SDL_HINT_MAC_OPENGL_ASYNC_DISPATCH, SDL_OpenGLAsyncDispatchChanged, NULL);
@@ -158,6 +188,15 @@ - (void)explicitUpdate
- (void)dealloc
{
SDL_DelHintCallback(SDL_HINT_MAC_OPENGL_ASYNC_DISPATCH, SDL_OpenGLAsyncDispatchChanged, NULL);
+ if (self->displayLink) {
+ CVDisplayLinkRelease(self->displayLink);
+ }
+ if (self->swapIntervalCond) {
+ SDL_DestroyCond(self->swapIntervalCond);
+ }
+ if (self->swapIntervalMutex) {
+ SDL_DestroyMutex(self->swapIntervalMutex);
+ }
}
@end
@@ -211,6 +250,7 @@ - (void)dealloc
int glversion_major;
int glversion_minor;
NSOpenGLPixelFormatAttribute profile;
+ int interval;
if (_this->gl_config.profile_mask == SDL_GL_CONTEXT_PROFILE_ES) {
#if SDL_VIDEO_OPENGL_EGL
@@ -318,6 +358,10 @@ - (void)dealloc
sdlcontext = (SDL_GLContext)CFBridgingRetain(context);
+ /* vsync is handled separately by synchronizing with a display link. */
+ interval = 0;
+ [context setValues:&interval forParameter:NSOpenGLCPSwapInterval];
+
if ( Cocoa_GL_MakeCurrent(_this, window, (__bridge SDL_GLContext)context) < 0 ) {
Cocoa_GL_DeleteContext(_this, (__bridge SDL_GLContext)context);
SDL_SetError("Failed making OpenGL context current");
@@ -389,21 +433,17 @@ - (void)dealloc
Cocoa_GL_SetSwapInterval(_THIS, int interval)
{ @autoreleasepool
{
- NSOpenGLContext *nscontext;
- GLint value;
+ SDLOpenGLContext *nscontext = (__bridge SDLOpenGLContext *) SDL_GL_GetCurrentContext();
int status;
- if (interval < 0) { /* no extension for this on Mac OS X at the moment. */
- return SDL_SetError("Late swap tearing currently unsupported");
- }
-
- nscontext = (__bridge NSOpenGLContext*)SDL_GL_GetCurrentContext();
- if (nscontext != nil) {
- value = interval;
- [nscontext setValues:&value forParameter:NSOpenGLCPSwapInterval];
- status = 0;
- } else {
+ if (nscontext == nil) {
status = SDL_SetError("No current OpenGL context");
+ } else {
+ SDL_LockMutex(nscontext->swapIntervalMutex);
+ SDL_AtomicSet(&nscontext->swapIntervalsPassed, 0);
+ SDL_AtomicSet(&nscontext->swapIntervalSetting, interval);
+ SDL_UnlockMutex(nscontext->swapIntervalMutex);
+ status = 0;
}
return status;
@@ -413,17 +453,8 @@ - (void)dealloc
Cocoa_GL_GetSwapInterval(_THIS)
{ @autoreleasepool
{
- NSOpenGLContext *nscontext;
- GLint value;
- int status = 0;
-
- nscontext = (__bridge NSOpenGLContext*)SDL_GL_GetCurrentContext();
- if (nscontext != nil) {
- [nscontext getValues:&value forParameter:NSOpenGLCPSwapInterval];
- status = (int)value;
- }
-
- return status;
+ SDLOpenGLContext* nscontext = (__bridge SDLOpenGLContext*)SDL_GL_GetCurrentContext();
+ return nscontext ? SDL_AtomicGet(&nscontext->swapIntervalSetting) : 0;
}}
int
@@ -432,6 +463,25 @@ - (void)dealloc
{
SDLOpenGLContext* nscontext = (__bridge SDLOpenGLContext*)SDL_GL_GetCurrentContext();
SDL_VideoData *videodata = (__bridge SDL_VideoData *) _this->driverdata;
+ const int setting = SDL_AtomicGet(&nscontext->swapIntervalSetting);
+
+ if (setting == 0) {
+ /* nothing to do if vsync is disabled, don't even lock */
+ } else if (setting < 0) { /* late swap tearing */
+ SDL_LockMutex(nscontext->swapIntervalMutex);
+ while (SDL_AtomicGet(&nscontext->swapIntervalsPassed) == 0) {
+ SDL_CondWait(nscontext->swapIntervalCond, nscontext->swapIntervalMutex);
+ }
+ SDL_AtomicSet(&nscontext->swapIntervalsPassed, 0);
+ SDL_UnlockMutex(nscontext->swapIntervalMutex);
+ } else {
+ SDL_LockMutex(nscontext->swapIntervalMutex);
+ do { /* always wait here so we know we just hit a swap interval. */
+ SDL_CondWait(nscontext->swapIntervalCond, nscontext->swapIntervalMutex);
+ } while ((SDL_AtomicGet(&nscontext->swapIntervalsPassed) % setting) != 0);
+ SDL_AtomicSet(&nscontext->swapIntervalsPassed, 0);
+ SDL_UnlockMutex(nscontext->swapIntervalMutex);
+ }
/* on 10.14 ("Mojave") and later, this deadlocks if two contexts in two
threads try to swap at the same time, so put a mutex around it. */