func DepthRangef(n float32, f float32) {
	syscall.Syscall(gpDepthRangef, 2, uintptr(math.Float32bits(n)), uintptr(math.Float32bits(f)), 0)
}
func DepthRangef(n float32, f float32) {
	syscall.Syscall(gpDepthRangef, 2, uintptr(math.Float32bits(n)), uintptr(math.Float32bits(f)), 0)
}
// specify mapping of depth values from normalized device coordinates to window coordinates