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NSGL: Implement swap interval with CVDisplayLink

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This fixes OpenGL swap interval (vsync) on macOS 10.14 Mojave by using
CVDisplayLink to synchronise to the monitor refresh rate rather than
setting NSOpenGLContextParameterSwapInterval.

Solution based on advice provided by @rcgordon.

Closes #1417.
This commit is contained in:
amarcu5 2019-01-14 02:11:28 +00:00 committed by Camilla Löwy
parent 4e3204d86d
commit 82ca58da04
2 changed files with 60 additions and 8 deletions
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12
src/nsgl_context.h Normal file → Executable file
View File

@ -27,13 +27,21 @@
#define _GLFW_PLATFORM_CONTEXT_STATE _GLFWcontextNSGL nsgl
#define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE _GLFWlibraryNSGL nsgl
#import <CoreVideo/CoreVideo.h>
#include <stdatomic.h>
// NSGL-specific per-context data
//
typedef struct _GLFWcontextNSGL
{
id pixelFormat;
id object;
id pixelFormat;
id object;
CVDisplayLinkRef displayLink;
atomic_int swapInterval;
int swapIntervalsPassed;
id swapIntervalCond;
} _GLFWcontextNSGL;

56
src/nsgl_context.m Normal file → Executable file
View File

@ -31,6 +31,27 @@
#define NSOpenGLContextParameterSurfaceOpacity NSOpenGLCPSurfaceOpacity
#endif
static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink,
const CVTimeStamp* now,
const CVTimeStamp* outputTime,
CVOptionFlags flagsIn,
CVOptionFlags* flagsOut,
void* userInfo)
{
_GLFWwindow* window = (_GLFWwindow *) userInfo;
const int setting = atomic_load(&window->context.nsgl.swapInterval);
if (setting > 0)
{
[window->context.nsgl.swapIntervalCond lock];
window->context.nsgl.swapIntervalsPassed++;
[window->context.nsgl.swapIntervalCond signal];
[window->context.nsgl.swapIntervalCond unlock];
}
return kCVReturnSuccess;
}
static void makeContextCurrentNSGL(_GLFWwindow* window)
{
@autoreleasepool {
@ -48,21 +69,33 @@ static void makeContextCurrentNSGL(_GLFWwindow* window)
static void swapBuffersNSGL(_GLFWwindow* window)
{
@autoreleasepool {
const int setting = atomic_load(&window->context.nsgl.swapInterval);
if (setting > 0)
{
[window->context.nsgl.swapIntervalCond lock];
do
{
[window->context.nsgl.swapIntervalCond wait];
} while (window->context.nsgl.swapIntervalsPassed % setting != 0);
window->context.nsgl.swapIntervalsPassed = 0;
[window->context.nsgl.swapIntervalCond unlock];
}
// ARP appears to be unnecessary, but this is future-proof
[window->context.nsgl.object flushBuffer];
} // autoreleasepool
}
static void swapIntervalNSGL(int interval)
{
@autoreleasepool {
_GLFWwindow* window = _glfwPlatformGetTls(&_glfw.contextSlot);
GLint sync = interval;
[window->context.nsgl.object setValues:&sync
forParameter:NSOpenGLContextParameterSwapInterval];
atomic_store(&window->context.nsgl.swapInterval, interval);
[window->context.nsgl.swapIntervalCond lock];
window->context.nsgl.swapIntervalsPassed = 0;
[window->context.nsgl.swapIntervalCond unlock];
} // autoreleasepool
}
@ -330,6 +363,17 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
window->context.getProcAddress = getProcAddressNSGL;
window->context.destroy = destroyContextNSGL;
CVDisplayLinkCreateWithActiveCGDisplays(&window->context.nsgl.displayLink);
CVDisplayLinkSetOutputCallback(window->context.nsgl.displayLink,
&displayLinkCallback,
window);
CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(window->context.nsgl.displayLink,
(CGLContextObj) window->context.nsgl.object,
(CGLPixelFormatObj) window->context.nsgl.pixelFormat);
CVDisplayLinkStart(window->context.nsgl.displayLink);
window->context.nsgl.swapIntervalCond = [NSCondition new];
return GLFW_TRUE;
}