From 738c06c28d8e377a4d7e7a1d84fc1e09392ed854 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@hajimehoshi.com>
Date: Sat, 11 Jan 2014 11:18:55 +0900
Subject: [PATCH] Add gl.go

---
 graphics/opengl/context.go | 13 ++++---------
 graphics/opengl/gl.go      | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 9 deletions(-)
 create mode 100644 graphics/opengl/gl.go

diff --git a/graphics/opengl/context.go b/graphics/opengl/context.go
index fa1e8a65b..277528d0f 100644
--- a/graphics/opengl/context.go
+++ b/graphics/opengl/context.go
@@ -1,10 +1,5 @@
 package opengl
 
-// #cgo LDFLAGS: -framework OpenGL
-//
-// #include <stdlib.h>
-// #include <OpenGL/gl.h>
-import "C"
 import (
 	"github.com/hajimehoshi/go-ebiten/graphics"
 	"github.com/hajimehoshi/go-ebiten/graphics/matrix"
@@ -38,6 +33,8 @@ func newContext(ids *ids, screenWidth, screenHeight, screenScale int) *Context {
 	context.ResetOffscreen()
 	context.Clear()
 
+	enableAlphaBlending()
+
 	return context
 }
 
@@ -47,9 +44,6 @@ func (context *Context) Dispose() {
 }
 
 func (context *Context) update(draw func(graphics.Context)) {
-	C.glEnable(C.GL_TEXTURE_2D)
-	C.glEnable(C.GL_BLEND)
-
 	context.ResetOffscreen()
 	context.Clear()
 
@@ -63,7 +57,8 @@ func (context *Context) update(draw func(graphics.Context)) {
 	geometryMatrix.Scale(scale, scale)
 	context.DrawRenderTarget(context.screenId,
 		geometryMatrix, matrix.IdentityColor())
-	C.glFlush()
+
+	flush()
 }
 
 func (context *Context) Clear() {
diff --git a/graphics/opengl/gl.go b/graphics/opengl/gl.go
new file mode 100644
index 000000000..12b745eb4
--- /dev/null
+++ b/graphics/opengl/gl.go
@@ -0,0 +1,16 @@
+package opengl
+
+// #cgo LDFLAGS: -framework OpenGL
+//
+// #include <stdlib.h>
+// #include <OpenGL/gl.h>
+import "C"
+
+func enableAlphaBlending() {
+	C.glEnable(C.GL_TEXTURE_2D)
+	C.glEnable(C.GL_BLEND)
+}
+
+func flush() {
+	C.glFlush()
+}