class_docstr: Torch autograd Function wrapper FacePointDistance Cuda implementation
code: def backward(ctx, grad_dists):
      grad_dists = grad_dists.contiguous()
      points, tris, idxs = ctx.saved_tensors
      min_triangle_area = ctx.min_triangle_area
      grad_points, grad_tris = _C.face_point_dist_backward(
          points, tris, idxs, grad_dists, min_triangle_area
      )
      return grad_points, None, grad_tris, None, None, None
  
imports: from pytorch3d import _C
  from pytorch3d.structures import Meshes, Pointclouds
  from torch.autograd import Function
  from torch.autograd.function import once_differentiable
label_desc: Use image node_id 2 for calling the _FacePointDistance obj's underlying member method code with example usage: obj.backward(ctx, grad_dists) and returns: grad_points,  None,  grad_tris,  None,  None,  None