[BUG] Error Sampling Result for Furthest Point Sampling

[qinglew]

I build the pointnet2_ops on Windows 10, and the version of Python is 3.7. When I use the furthest_point_sample and gather_operation to sample points from a dense point cloud, I find that there is a bug in the algorithm:

Here is the dense point cloud:

After use fps to sample 2048 points, there is a hole on the plane:

[qinglew]

It happened many times when apply to different models.