Is It Possible To Snap To A Custom Shape Node's Vertices?

[mcneja]

We have a proxy geometry plugin which is currently derived from MPxLocatorNode. One of the enhancements I've been trying to add is the ability to snap other geometry to our custom proxy geometry. I was thinking of deriving from MPxSurfaceShape instead since it supports vertex components.

I tried out the apiMeshShape sample plugin that comes with Maya 8.5 and you can't snap to the verts in the custom shape (you can snap custom shape verts to normal Maya mesh verts, though). Does anyone know a way to make custom geometry which can be a snap target?

Six years ago someone asked this same question but there weren't any responses:

http://www.highend3d.com/boards/index.php?showtopic=141298

[mcneja]

I've been poking at this some more. It appears that the custom shape node's MPxSurfaceShapeUI::select method does get called during vertex snapping (if you're moving a vert on another mesh, say). No matter what I've tried, though, Maya always ignores the vertex I add to the MSelectInfo object, instead choosing vertices on other, ordinary Maya meshes.

Does anyone know what the secret is to creating vertex selections that Maya will consider acceptable snap targets?

Thanks,
James