Fix plotly pointcloud visualization feature bug

Summary: If a pointcloud had less than pointcloud_max_points, the colors would not render. This diff fixes that.

Reviewed By: bottler

Differential Revision: D25099044

fbshipit-source-id: 47c3ddcdb4e06284b0a7966ffca1b973f394921f

pytorch3d/vis/plotly_vis.py

@@ -587,7 +587,9 @@ def _add_pointcloud_trace(
 
     color = None
     if features is not None:
-        features = features[indices]
+        if indices is not None:
+            # Only select features if we selected vertices above
+            features = features[indices]
         if features.shape[1] == 4:  # rgba
             template = "rgb(%d, %d, %d, %f)"
             rgb = (features[:, :3].clamp(0.0, 1.0) * 255).int()