func StencilFunc(xfunc uint32, ref int32, mask uint32) {
	C.glowStencilFunc(gpStencilFunc, (C.GLenum)(xfunc), (C.GLint)(ref), (C.GLuint)(mask))
}
func StencilFunc(xfunc uint32, ref int32, mask uint32) {
	C.glowStencilFunc(gpStencilFunc, (C.GLenum)(xfunc), (C.GLint)(ref), (C.GLuint)(mask))
}
// set front and back function and reference value for stencil testing