3 files changed, 38 insertions, 1 deletions
diff --git a/emulator/opengl/host/libs/Translator/EGL/EglMacApi.cpp b/emulator/opengl/host/libs/Translator/EGL/EglMacApi.cpp
index 31527af..eeaa25c 100644
--- a/emulator/opengl/host/libs/Translator/EGL/EglMacApi.cpp
+++ b/emulator/opengl/host/libs/Translator/EGL/EglMacApi.cpp
@@ -68,7 +68,15 @@ static EglConfig* pixelFormatToConfig(int index,int renderableType,EGLNativePixe
 
     getPixelFormatAttrib(*frmt,MAC_SAMPLES_PER_PIXEL,&samples);
     getPixelFormatAttrib(*frmt,MAC_COLOR_SIZE,&colorSize);
-    getPixelFormatAttrib(*frmt,MAC_ALPHA_SIZE,&alpha);
+    /* All configs can end up having an alpha channel even if none was requested.
+     * The default config chooser in GLSurfaceView will therefore not find any
+     * matching config. Thus, make sure alpha is zero (or at least signalled as
+     * zero to the calling EGL layer) for the configs where it was intended to
+     * be zero. */
+    if (getPixelFormatDefinitionAlpha(index) == 0)
+        alpha = 0;
+    else
+        getPixelFormatAttrib(*frmt,MAC_ALPHA_SIZE,&alpha);
     getPixelFormatAttrib(*frmt,MAC_DEPTH_SIZE,&depth);
     getPixelFormatAttrib(*frmt,MAC_STENCIL_SIZE,&stencil);
 
diff --git a/emulator/opengl/host/libs/Translator/EGL/MacNative.h b/emulator/opengl/host/libs/Translator/EGL/MacNative.h
index 82ab667..c8a1df2 100644
--- a/emulator/opengl/host/libs/Translator/EGL/MacNative.h
+++ b/emulator/opengl/host/libs/Translator/EGL/MacNative.h
@@ -33,6 +33,7 @@ extern "C"{
 
 int   getNumPixelFormats();
 void* getPixelFormat(int i);
+int   getPixelFormatDefinitionAlpha(int i);
 void  getPixelFormatAttrib(void* pixelFormat,int attrib,int* val);
 void* nsCreateContext(void* format,void* share);
 void  nsWindowMakeCurrent(void* context,void* nativeWin);
diff --git a/emulator/opengl/host/libs/Translator/EGL/MacNative.m b/emulator/opengl/host/libs/Translator/EGL/MacNative.m
index 6828655..a2cea93 100644
--- a/emulator/opengl/host/libs/Translator/EGL/MacNative.m
+++ b/emulator/opengl/host/libs/Translator/EGL/MacNative.m
@@ -75,6 +75,34 @@ void* getPixelFormat(int i){
     return [[NSOpenGLPixelFormat alloc] initWithAttributes:attrib_lists[i]];
 }
 
+int getPixelFormatDefinitionAlpha(int i) {
+    int size;
+    NSOpenGLPixelFormatAttribute** attrib_lists = getPixelFormatsAttributes(&size);
+    NSOpenGLPixelFormatAttribute* attribs = attrib_lists[i];
+    while (*attribs) {
+        switch (*attribs) {
+        // These are the ones that take a value, according to the current
+        // NSOpenGLPixelFormat docs
+        case NSOpenGLPFAAuxBuffers:
+        case NSOpenGLPFAColorSize:
+        case NSOpenGLPFADepthSize:
+        case NSOpenGLPFAStencilSize:
+        case NSOpenGLPFAAccumSize:
+        case NSOpenGLPFARendererID:
+        case NSOpenGLPFAScreenMask:
+            attribs += 2;
+            break;
+        case NSOpenGLPFAAlphaSize:
+            return attribs[1];
+            break;
+        // All other attributes are boolean attributes that don't take a value
+        default:
+            attribs++;
+        }
+    }
+    return 0;
+}
+
 void getPixelFormatAttrib(void* pixelFormat,int attrib,int* val){
     NSOpenGLPixelFormat *frmt = (NSOpenGLPixelFormat *)pixelFormat;
     [frmt getValues:val forAttribute:attrib forVirtualScreen:0];