internal/graphicsdriver/opengl/gl/package_notwindows.go
func AlphaFunc(xfunc uint32, ref float32) {
	C.glowAlphaFunc(gpAlphaFunc, (C.GLenum)(xfunc), (C.GLfloat)(ref))
}
func AlphaFunc(xfunc uint32, ref float32) {
	C.glowAlphaFunc(gpAlphaFunc, (C.GLenum)(xfunc), (C.GLfloat)(ref))
}
func AlphaFunc ( xfunc uint32 , ref float32 ) { C . glowAlphaFunc ( gpAlphaFunc , ( C . GLenum ) ( xfunc ) , ( C . GLfloat ) ( ref ) ) }
// specify the alpha test function
specify the alpha test function