func StencilFunc(xfunc uint32, ref int32, mask uint32) {
	syscall.Syscall(gpStencilFunc, 3, uintptr(xfunc), uintptr(ref), uintptr(mask))
}
func StencilFunc(xfunc uint32, ref int32, mask uint32) {
	syscall.Syscall(gpStencilFunc, 3, uintptr(xfunc), uintptr(ref), uintptr(mask))
}
func StencilFunc ( xfunc uint32 , ref int32 , mask uint32 ) { syscall . Syscall ( gpStencilFunc , 3 , uintptr ( xfunc ) , uintptr ( ref ) , uintptr ( mask ) ) }
// set front and back function and reference value for stencil testing
set front and back function and reference value for stencil testing