golang + OSMesa

go-gl.patch

diff --git a/gl.go b/gl.go
index 89581f3..8ba19cb 100644
--- a/gl.go
+++ b/gl.go
@@ -4,13 +4,8 @@
 
 package gl
 
-// #cgo darwin LDFLAGS: -framework OpenGL -lGLEW
-// #cgo windows LDFLAGS: -lglew32 -lopengl32
-// #cgo linux LDFLAGS: -lGLEW -lGL
-// #cgo freebsd  CFLAGS: -I/usr/local/include
-// #cgo freebsd LDFLAGS: -L/usr/local/lib -lglfw
+// #cgo LDFLAGS: -lOSMesa
 // #include "gl.h"
-// void SetGlewExperimental(GLboolean v) {  glewExperimental = v;  }
 import "C"
 import "unsafe"
 import "reflect"
@@ -1156,6 +1151,5 @@ func Viewport(x int, y int, width int, height int) {
 //}
 
 func Init() GLenum {
-	C.SetGlewExperimental(C.GLboolean(1))
-	return GLenum(C.glewInit())
+    return 0;
 }
diff --git a/gl.h b/gl.h
index 17e42c7..1b0d722 100644
--- a/gl.h
+++ b/gl.h
@@ -1,5 +1,5 @@
+#define GL_GLEXT_PROTOTYPES
+
 #include <stdlib.h>
-#include <GL/glew.h>
+#include <GL/osmesa.h>
 
-#undef GLEW_GET_FUN
-#define GLEW_GET_FUN(x) (*x)
\ No newline at end of file

triangle.go

package main

import "os"
import "image"
import "image/png"
import "unsafe"

import "github.com/go-gl/gl"
import "github.com/go-gl/osmesa"

func draw() {
	gl.Begin(gl.TRIANGLES)
		gl.Vertex2f(0,0)
		gl.Vertex2f(0,1)
		gl.Vertex2f(1,1)
	gl.End()
}

func main() {

	var ctx = osmesa.CreateContext(osmesa.RGBA, nil)
	defer osmesa.DestroyContext(ctx)

	image := image.NewRGBA(image.Rect(0, 0, 640, 480))

	osmesa.MakeCurrent(ctx, unsafe.Pointer(&(image.Pix[0])), gl.UNSIGNED_BYTE, 640, 480)

	gl.ClearColor(1.0, 0.5, 0.23, 1.0)
	gl.Clear(gl.COLOR_BUFFER_BIT)

	draw();
	gl.Flush();


	fd, err := os.Create("output.png")
	if err != nil {
		panic(err)
	}
	defer fd.Close()
 
	png.Encode(fd, image)

}