func ClearDepthf(d float32) {
	syscall.Syscall(gpClearDepthf, 1, uintptr(math.Float32bits(d)), 0, 0)
}
func ClearDepthf(d float32) {
	syscall.Syscall(gpClearDepthf, 1, uintptr(math.Float32bits(d)), 0, 0)
}
func ClearDepthf ( d float32 ) { syscall . Syscall ( gpClearDepthf , 1 , uintptr ( math . Float32bits ( d ) ) , 0 , 0 ) }
// specify the clear value for the depth buffer
specify the clear value for the depth buffer