func FlushMappedBufferRange(target uint32, offset int, length int) {
	syscall.Syscall(gpFlushMappedBufferRange, 3, uintptr(target), uintptr(offset), uintptr(length))
}
func FlushMappedBufferRange(target uint32, offset int, length int) {
	syscall.Syscall(gpFlushMappedBufferRange, 3, uintptr(target), uintptr(offset), uintptr(length))
}
// indicate modifications to a range of a mapped buffer