Fixed bug 5440 - MacCatalyst build failures

C.W. Betts

I tested building commit http://hg.libsdl.org/SDL/rev/7adf3fdc19f3 on Mac Catalyst and found some issues:

* MTLFeatureSet_iOS_* enums aren't available under Mac Catalyst.
* OpenGL ES is unavailable under Mac Catalyst.
* Some Metal features are available under Catalyst but not iOS, such as displaySyncEnabled.
* Set Metal as the default renderer on Mac Catalyst

Attaching a patch that will make SDL2 build for Mac Catalyst.

Xcode/SDL/SDL.xcodeproj/project.pbxproj

@@ -3,7 +3,7 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 46;
+	objectVersion = 52;
 	objects = {
 
 /* Begin PBXBuildFile section */
@@ -3728,7 +3728,7 @@
 		DB31408D17554D3C006C0E22 /* ForceFeedback.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 00CFA89C106B4BA100758660 /* ForceFeedback.framework */; };
 		F3631C6424884ACF004F28EA /* SDL_locale.h in Headers */ = {isa = PBXBuildFile; fileRef = 566E26792462701100718109 /* SDL_locale.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		F3631C652488534E004F28EA /* SDL_locale.h in Headers */ = {isa = PBXBuildFile; fileRef = 566E26792462701100718109 /* SDL_locale.h */; settings = {ATTRIBUTES = (Public, ); }; };
-		F376F6192559B29300CFC0BC /* OpenGLES.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = F376F6182559B29300CFC0BC /* OpenGLES.framework */; };
+		F376F6192559B29300CFC0BC /* OpenGLES.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = F376F6182559B29300CFC0BC /* OpenGLES.framework */; platformFilter = ios; };
 		F376F61B2559B2AF00CFC0BC /* UIKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = F376F61A2559B2AF00CFC0BC /* UIKit.framework */; };
 		F376F6262559B30000CFC0BC /* UIKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = F376F61A2559B2AF00CFC0BC /* UIKit.framework */; };
 		F376F6322559B31D00CFC0BC /* GameController.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = F376F6312559B31D00CFC0BC /* GameController.framework */; };
@@ -10038,7 +10038,11 @@
 				);
 				INFOPLIST_FILE = "Info-Framework.plist";
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+					"@loader_path/Frameworks",
+				);
 				MACOSX_DEPLOYMENT_TARGET = 10.6;
 				PRODUCT_BUNDLE_IDENTIFIER = org.libsdl.SDL2;
 				PRODUCT_NAME = SDL2;
@@ -10117,7 +10121,11 @@
 				);
 				INFOPLIST_FILE = "Info-Framework.plist";
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
-				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
+				LD_RUNPATH_SEARCH_PATHS = (
+					"$(inherited)",
+					"@executable_path/Frameworks",
+					"@loader_path/Frameworks",
+				);
 				MACOSX_DEPLOYMENT_TARGET = 10.6;
 				ONLY_ACTIVE_ARCH = YES;
 				PRODUCT_BUNDLE_IDENTIFIER = org.libsdl.SDL2;

include/SDL_config_iphoneos.h

@@ -170,10 +170,12 @@
 #define SDL_VIDEO_DRIVER_DUMMY  1
 
 /* Enable OpenGL ES */
+#if !TARGET_OS_MACCATALYST
 #define SDL_VIDEO_OPENGL_ES2 1
 #define SDL_VIDEO_OPENGL_ES 1
 #define SDL_VIDEO_RENDER_OGL_ES 1
 #define SDL_VIDEO_RENDER_OGL_ES2    1
+#endif
 
 /* Metal supported on 64-bit devices running iOS 8.0 and tvOS 9.0 and newer
    Also supported in simulator from iOS 13.0 and tvOS 13.0

src/render/metal/SDL_render_metal.m

@@ -59,7 +59,7 @@ extern int SDL_RecreateWindow(SDL_Window * window, Uint32 flags);
 
 /* macOS requires constants in a buffer to have a 256 byte alignment. */
 /* Use native type alignments from https://developer.apple.com/metal/Metal-Shading-Language-Specification.pdf */
-#if defined(__MACOSX__) || TARGET_OS_SIMULATOR
+#if defined(__MACOSX__) || TARGET_OS_SIMULATOR || TARGET_OS_MACCATALYST
 #define CONSTANT_ALIGN(x) (256)
 #else
 #define CONSTANT_ALIGN(x) (x < 4 ? 4 : x)
@@ -1875,7 +1875,7 @@ METAL_CreateRenderer(SDL_Window * window, Uint32 flags)
 
     renderer->always_batch = SDL_TRUE;
 
-#if defined(__MACOSX__) && defined(MAC_OS_X_VERSION_10_13)
+#if (defined(__MACOSX__) && defined(MAC_OS_X_VERSION_10_13)) || TARGET_OS_MACCATALYST
     if (@available(macOS 10.13, *)) {
         data.mtllayer.displaySyncEnabled = (flags & SDL_RENDERER_PRESENTVSYNC) != 0;
         if (data.mtllayer.displaySyncEnabled) {
@@ -1889,7 +1889,7 @@ METAL_CreateRenderer(SDL_Window * window, Uint32 flags)
 
     /* https://developer.apple.com/metal/Metal-Feature-Set-Tables.pdf */
     int maxtexsize = 4096;
-#if defined(__MACOSX__)
+#if defined(__MACOSX__) || TARGET_OS_MACCATALYST
     maxtexsize = 16384;
 #elif defined(__TVOS__)
     maxtexsize = 8192;

src/video/SDL_video.c

@@ -1474,10 +1474,14 @@ SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
     }
 
     /* Some platforms have OpenGL enabled by default */
-#if (SDL_VIDEO_OPENGL && __MACOSX__) || __IPHONEOS__ || __ANDROID__ || __NACL__
+#if (SDL_VIDEO_OPENGL && __MACOSX__) || (__IPHONEOS__ && !TARGET_OS_MACCATALYST) || __ANDROID__ || __NACL__
     if (!_this->is_dummy && !(flags & SDL_WINDOW_VULKAN) && !(flags & SDL_WINDOW_METAL) && !SDL_IsVideoContextExternal()) {
         flags |= SDL_WINDOW_OPENGL;
     }
+#elif TARGET_OS_MACCATALYST
+    if (!_this->is_dummy && !(flags & SDL_WINDOW_VULKAN) && !(flags & SDL_WINDOW_OPENGL) && !SDL_IsVideoContextExternal()) {
+        flags |= SDL_WINDOW_METAL;
+    }
 #endif
     if (flags & SDL_WINDOW_OPENGL) {
         if (!_this->GL_CreateContext) {