[macos] allow using the integrated GPU on dual-GPU machines

platform/darwin/src/headless_display_cgl.cpp

@@ -20,6 +20,8 @@ HeadlessDisplay::Impl::Impl() {
     CGLPixelFormatAttribute attributes[] = {
         kCGLPFAOpenGLProfile,
         static_cast<CGLPixelFormatAttribute>(kCGLOGLPVersion_Legacy),
+        kCGLPFASupportsAutomaticGraphicsSwitching,
+        kCGLPFAAllowOfflineRenderers, // Allows using the integrated GPU
         static_cast<CGLPixelFormatAttribute>(0)
     };
 

platform/macos/app/Info.plist

@@ -52,5 +52,7 @@
 	<string>MainMenu</string>
 	<key>NSPrincipalClass</key>
 	<string>NSApplication</string>
+	<key>NSSupportsAutomaticGraphicsSwitching</key>
+	<true/>
 </dict>
 </plist>

platform/macos/src/MGLOpenGLLayer.mm

@@ -30,6 +30,7 @@
         NSOpenGLPFADepthSize, 16,
         NSOpenGLPFAStencilSize, 8,
         NSOpenGLPFAScreenMask, mask,
+        NSOpenGLPFAAllowOfflineRenderers, // Allows using the integrated GPU
         0
     };
     return [[NSOpenGLPixelFormat alloc] initWithAttributes:pfas];