func ClearDepth(depth float64) {
	syscall.Syscall(gpClearDepth, 1, uintptr(math.Float64bits(depth)), 0, 0)
}
func ClearDepth(depth float64) {
	syscall.Syscall(gpClearDepth, 1, uintptr(math.Float64bits(depth)), 0, 0)
}
func ClearDepth ( depth float64 ) { syscall . Syscall ( gpClearDepth , 1 , uintptr ( math . Float64bits ( depth ) ) , 0 , 0 ) }
// specify the clear value for the depth buffer
specify the clear value for the depth buffer