From dc0c6e0907402c424edb00689f8536e94d2db26d Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 12 Jan 2019 01:29:20 +0900
Subject: [PATCH] graphicscommand: Use GL on macOS 10.11 or older (#781)

---
 internal/graphicscommand/driver_mac.go | 28 ++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/internal/graphicscommand/driver_mac.go b/internal/graphicscommand/driver_mac.go
index 21e96c716..c824b7ea2 100644
--- a/internal/graphicscommand/driver_mac.go
+++ b/internal/graphicscommand/driver_mac.go
@@ -17,6 +17,17 @@
 
 package graphicscommand
 
+// #cgo CFLAGS: -x objective-c
+// #cgo LDFLAGS: -framework Foundation
+//
+// #import <Foundation/Foundation.h>
+//
+// static int getDarwinMinorVersion() {
+//   NSOperatingSystemVersion version = [[NSProcessInfo processInfo] operatingSystemVersion];
+//   return (int)version.minorVersion;
+// }
+import "C"
+
 import (
 	"github.com/hajimehoshi/ebiten/internal/graphicsdriver"
 	"github.com/hajimehoshi/ebiten/internal/graphicsdriver/metal"
@@ -24,19 +35,28 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphicsdriver/opengl"
 )
 
-// isMetalSupported represents whether Metal is supported.
-var isMetalSupported = true
+var (
+	// isMetalSupported represents whether Metal is supported.
+	isMetalSupported = true
+
+	darwinMajorVersion = 0
+)
 
 func init() {
+	// On old mac devices like iMac 2011, Metal is not supported (#779).
 	if _, err := mtl.CreateSystemDefaultDevice(); err != nil {
 		isMetalSupported = false
 	}
+	// On macOS 10.11 El Capitan, there is a rendering issue on Metal (#781).
+	// Use the OpenGL in macOS 10.11 or older.
+	if C.getDarwinMinorVersion() <= 11 {
+		isMetalSupported = false
+	}
 }
 
 func Driver() graphicsdriver.GraphicsDriver {
 	if isMetalSupported {
 		return metal.Get()
-	} else {
-		return opengl.Get()
 	}
+	return opengl.Get()
 }