func Accum(op uint32, value float32) {
	syscall.Syscall(gpAccum, 2, uintptr(op), uintptr(math.Float32bits(value)), 0)
}
func Accum(op uint32, value float32) {
	syscall.Syscall(gpAccum, 2, uintptr(op), uintptr(math.Float32bits(value)), 0)
}
// operate on the accumulation buffer