func IndexPointer(xtype uint32, stride int32, pointer unsafe.Pointer) {
	syscall.Syscall(gpIndexPointer, 3, uintptr(xtype), uintptr(stride), uintptr(pointer))
}
func IndexPointer(xtype uint32, stride int32, pointer unsafe.Pointer) {
	syscall.Syscall(gpIndexPointer, 3, uintptr(xtype), uintptr(stride), uintptr(pointer))
}
// define an array of color indexes