use metal preferredFramesPerSecond (macOS 10.11+) and commandBuffer presentDrawable:afterMinimumDuration: (macOS 10.15.4+)

(programmed from Windows, maybe do not compile)

src/macosx/OSXViewDelegate.m

@@ -4,6 +4,17 @@
 
 #import <MetalKit/MetalKit.h>
 
+extern double   g_time_for_frame;
+extern bool     g_use_hardware_sync;
+//--
+bool    g_target_fps_changed = true;
+
+//-------------------------------------
+void
+set_target_fps_aux() {
+    g_target_fps_changed = true;
+}
+
 //-------------------------------------
 #define kShader(inc, src)    @inc#src
 
@@ -157,6 +168,12 @@ NSString *g_shader_src = kShader(
 
 //-------------------------------------
 - (void) drawInMTKView:(nonnull MTKView *) view {
+    if (g_target_fps_changed) {
+        view.preferredFramesPerSecond = (int) (1.0 / g_time_for_frame);
+        g_target_fps_changed = false;
+        g_use_hardware_sync  = true;
+    }
+
     // Wait to ensure only MaxBuffersInFlight number of frames are getting proccessed
     // by any stage in the Metal pipeline (App, Metal, Drivers, GPU, etc)
     dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
@@ -205,8 +222,13 @@ NSString *g_shader_src = kShader(
         [renderEncoder endEncoding];
 
         // Schedule a present once the framebuffer is complete using the current drawable
+        if ([commandBuffer respondsToSelector:@selector(presentDrawable:afterMinimumDuration:)]) {
+            [commandBuffer presentDrawable:view.currentDrawable afterMinimumDuration:g_time_for_frame];
+        }
+        else {
             [commandBuffer presentDrawable:view.currentDrawable];
         }
+    }
 
     // Finalize rendering here & push the command buffer to the GPU
     [commandBuffer commit];