Multisampling does not work on MTLGPUFamilyApple2 devices when using …

…ANGLE Metal

https://bugs.webkit.org/show_bug.cgi?id=241456
<rdar://problem/90949957>

Patch by Kimmo Kinnunen <kkinnunen@apple.com> on 2022-06-09
Reviewed by Dean Jackson.

Use OpenGL ES for WebGL for devices prior to MTLGPUFamilyApple3.
WebGL2 already was running OpenGL ES for these devices for different reasons.

The multisample codepath is not implemented for Apple2 which
does not support MTLStoreActionStoreAndMultisampleResolve.

* Source/WebCore/platform/graphics/cocoa/GraphicsContextGLCocoa.mm:
(WebCore::platformSupportsMetal):
(WebCore::GraphicsContextGLCocoa::platformInitializeContext):

Canonical link: https://commits.webkit.org/251437@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@295431 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/platform/graphics/cocoa/GraphicsContextGLCocoa.mm

@@ -99,18 +99,15 @@ static bool checkVolatileContextSupportIfDeviceExists(EGLDisplay display, const
 }
 #endif
 
-static bool platformSupportsMetal(bool isWebGL2)
+static bool platformSupportsMetal()
 {
     auto device = adoptNS(MTLCreateSystemDefaultDevice());
 
     if (device) {
 #if PLATFORM(IOS_FAMILY) && !PLATFORM(IOS_FAMILY_SIMULATOR)
-        // A8 devices (iPad Mini 4, iPad Air 2) cannot use WebGL2 via Metal.
+        // A8 devices (iPad Mini 4, iPad Air 2) cannot use WebGL via Metal.
         // This check can be removed once they are no longer supported.
-        if (isWebGL2)
-            return [device supportsFamily:MTLGPUFamilyApple3];
-#else
-        UNUSED_PARAM(isWebGL2);
+        return [device supportsFamily:MTLGPUFamilyApple3];
 #endif
         return true;
     }
@@ -247,7 +244,7 @@ static bool needsEAGLOnMac()
 {
     GraphicsContextGLAttributes attributes = contextAttributes();
     m_isForWebGL2 = attributes.webGLVersion == GraphicsContextGLWebGLVersion::WebGL2;
-    if (attributes.useMetal && !platformSupportsMetal(m_isForWebGL2)) {
+    if (attributes.useMetal && !platformSupportsMetal()) {
         attributes.useMetal = false;
         setContextAttributes(attributes);
     }