zdoom-macos-deps/patch/glfw-fix-vsync.diff

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1057a6f9..36b3fe0b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -151,10 +151,11 @@ endif()
 if (GLFW_BUILD_COCOA)
     target_link_libraries(glfw PRIVATE "-framework Cocoa"
                                        "-framework IOKit"
-                                       "-framework CoreFoundation")
+                                       "-framework CoreFoundation"
+                                       "-framework CoreVideo")
 
     set(glfw_PKG_DEPS "")
-    set(glfw_PKG_LIBS "-framework Cocoa -framework IOKit -framework CoreFoundation")
+    set(glfw_PKG_LIBS "-framework Cocoa -framework IOKit -framework CoreFoundation -framework CoreVideo")
 endif()
 
 if (GLFW_BUILD_WAYLAND)
diff --git a/src/cocoa_platform.h b/src/cocoa_platform.h
index 39914554..ad32e83d 100644
--- a/src/cocoa_platform.h
+++ b/src/cocoa_platform.h
@@ -37,8 +37,10 @@
 
 #if defined(__OBJC__)
 #import <Cocoa/Cocoa.h>
+#import <CoreVideo/CoreVideo.h>
 #else
 typedef void* id;
+typedef void* CVDisplayLinkRef;
 #endif
 
 // NOTE: Many Cocoa enum values have been renamed and we need to build across
@@ -124,6 +126,10 @@ typedef struct _GLFWcontextNSGL
 {
     id                pixelFormat;
     id                object;
+    int               swapInterval;
+    int               swapIntervalsPassed;
+    id                swapIntervalCond;
+    CVDisplayLinkRef  displayLink;
 } _GLFWcontextNSGL;
 
 // NSGL-specific global data
@@ -299,4 +305,5 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
                                 const _GLFWctxconfig* ctxconfig,
                                 const _GLFWfbconfig* fbconfig);
 void _glfwDestroyContextNSGL(_GLFWwindow* window);
+void _glfwUpdateDisplayLinkNSGL(_GLFWwindow* window);
 
diff --git a/src/cocoa_window.m b/src/cocoa_window.m
index 0dcf0a38..a4a7ae41 100644
--- a/src/cocoa_window.m
+++ b/src/cocoa_window.m
@@ -320,6 +320,12 @@ - (void)windowDidChangeOcclusionState:(NSNotification* )notification
 #endif
 }
 
+- (void)windowDidChangeScreen:(NSNotification *)notification
+{
+    if (window->context.source == GLFW_NATIVE_CONTEXT_API)
+        _glfwUpdateDisplayLinkNSGL(window);
+}
+
 @end
 
 
diff --git a/src/nsgl_context.m b/src/nsgl_context.m
index daa8367a..b2c109d2 100644
--- a/src/nsgl_context.m
+++ b/src/nsgl_context.m
@@ -45,30 +45,42 @@ static void makeContextCurrentNSGL(_GLFWwindow* window)
     } // autoreleasepool
 }
 
+
+static CVReturn nsglDisplayLinkCallback(CVDisplayLinkRef displayLink,
+    const CVTimeStamp* now,
+    const CVTimeStamp* outputTime,
+    CVOptionFlags flagsIn,
+    CVOptionFlags* flagsOut,
+    void* userContext)
+{
+    _GLFWcontextNSGL* nsgl = (_GLFWcontextNSGL*)userContext;
+    NSCondition* intervalCond = nsgl->swapIntervalCond;
+
+    [intervalCond lock];
+    ++nsgl->swapIntervalsPassed;
+    [intervalCond signal];
+    [intervalCond unlock];
+
+    return kCVReturnSuccess;
+}
+
 static void swapBuffersNSGL(_GLFWwindow* window)
 {
     @autoreleasepool {
 
-    // HACK: Simulate vsync with usleep as NSGL swap interval does not apply to
-    //       windows with a non-visible occlusion state
-    if (window->ns.occluded)
+    if (window->context.nsgl.swapInterval > 0)
     {
-        int interval = 0;
-        [window->context.nsgl.object getValues:&interval
-                                  forParameter:NSOpenGLContextParameterSwapInterval];
+        [window->context.nsgl.swapIntervalCond lock];
 
-        if (interval > 0)
+        do
         {
-            const double framerate = 60.0;
-            const uint64_t frequency = _glfwPlatformGetTimerFrequency();
-            const uint64_t value = _glfwPlatformGetTimerValue();
-
-            const double elapsed = value / (double) frequency;
-            const double period = 1.0 / framerate;
-            const double delay = period - fmod(elapsed, period);
-
-            usleep(floorl(delay * 1e6));
+            // do-while guarantees at least one swap interval has occurred.
+            [window->context.nsgl.swapIntervalCond wait];
         }
+        while (window->context.nsgl.swapIntervalsPassed % window->context.nsgl.swapInterval != 0);
+
+        window->context.nsgl.swapIntervalsPassed = 0;
+        [window->context.nsgl.swapIntervalCond unlock];
     }
 
     [window->context.nsgl.object flushBuffer];
@@ -83,8 +95,7 @@ static void swapIntervalNSGL(int interval)
     _GLFWwindow* window = _glfwPlatformGetTls(&_glfw.contextSlot);
     assert(window != NULL);
 
-    [window->context.nsgl.object setValues:&interval
-                              forParameter:NSOpenGLContextParameterSwapInterval];
+    window->context.nsgl.swapInterval = interval;
 
     } // autoreleasepool
 }
@@ -113,6 +124,13 @@ static void destroyContextNSGL(_GLFWwindow* window)
 {
     @autoreleasepool {
 
+    CVDisplayLinkStop(window->context.nsgl.displayLink);
+    CVDisplayLinkRelease(window->context.nsgl.displayLink);
+    window->context.nsgl.displayLink = NULL;
+
+    [window->context.nsgl.swapIntervalCond release];
+    window->context.nsgl.swapIntervalCond = nil;
+
     [window->context.nsgl.pixelFormat release];
     window->context.nsgl.pixelFormat = nil;
 
@@ -344,6 +362,21 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
 
     [window->context.nsgl.object setView:window->ns.view];
 
+    window->context.nsgl.swapInterval = 0; // Default value of NSGL swap interval
+    window->context.nsgl.swapIntervalsPassed = 0;
+    window->context.nsgl.swapIntervalCond = [[NSCondition alloc] init];
+
+    // Explicitly set NSGL swap interval to 0, since CVDisplayLink will be used
+    // instead.
+    int swapInterval = 0;
+    [window->context.nsgl.object setValues:&swapInterval
+                              forParameter:NSOpenGLContextParameterSwapInterval];
+
+    CVDisplayLinkCreateWithActiveCGDisplays(&window->context.nsgl.displayLink);
+    CVDisplayLinkSetOutputCallback(window->context.nsgl.displayLink, &nsglDisplayLinkCallback, &window->context.nsgl);
+    _glfwUpdateDisplayLinkNSGL(window);
+    CVDisplayLinkStart(window->context.nsgl.displayLink);
+
     window->context.makeCurrent = makeContextCurrentNSGL;
     window->context.swapBuffers = swapBuffersNSGL;
     window->context.swapInterval = swapIntervalNSGL;
@@ -354,6 +387,13 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
     return GLFW_TRUE;
 }
 
+void _glfwUpdateDisplayLinkNSGL(_GLFWwindow* window)
+{
+    CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(window->context.nsgl.displayLink,
+        [window->context.nsgl.object CGLContextObj],
+        [window->context.nsgl.pixelFormat CGLPixelFormatObj]);
+}
+
 
 //////////////////////////////////////////////////////////////////////////
 //////                        GLFW native API                       //////