Fix indices_to_points to make it consistent to VoxelMesh.as_boxes

[wkentaro]

I'm not so sure, but usually voxel point coordinate should be calculated as:

(index - 0.5) * pitch + origin = index * pitch + origin - pitch / 2.0

In VoxelMesh.as_boxes this formulation is used, but the matrix_to_points function does not.

[mikedh]

Yeah, you're right it should definitely be consistent. Maybe we should make two functions, points_to_indices and indices_to_points to avoid screwing up the logic, then we can add a round trip or two into unit tests.

Some quick thoughts:

• probably want to make sure indices is float before doing the operation, and check the other inputs
• in as_boxes, it needs to be self.pitch, not pitch
• generally probably want to use kwargs rather than args when calling functions (pitch=self.pitch vs pitch), makes it more explicit and CI will start failing if someone decides to rearrange args.

[wkentaro]

I added points_to_indices and tests for both functions. Could you review again?

[coveralls]

Coverage increased (+0.1%) to 84.096% when pulling a83f42f on wkentaro:indices_to_points into 5953bed on mikedh:voxel_merge.

[coveralls]

Coverage increased (+0.1%) to 84.096% when pulling a83f42f on wkentaro:indices_to_points into 5953bed on mikedh:voxel_merge.

[coveralls]

Coverage increased (+0.1%) to 84.096% when pulling a83f42f on wkentaro:indices_to_points into 5953bed on mikedh:voxel_merge.

[coveralls]

Coverage decreased (-0.003%) to 83.974% when pulling a83f42f on wkentaro:indices_to_points into 5953bed on mikedh:voxel_merge.

[mikedh]

Looks great, thanks!