TransformControls: Remove warning when activate rotate

[Mugen87]

Currently, TransformControls produces a warning when switching into "rotate" mode.

[.Offscreen-For-WebGL-0x7fc831865a00]RENDER WARNING: Render count or primcount is 0.

The warning was produced by a picker gizmo with an empty geometry.

Before: https://threejs.org/examples/misc_controls_transform.html
After: https://rawgit.com/Mugen87/three.js/dev11/examples/misc_controls_transform.html

[Mugen87]

I have seen this warning several times in the editor and always wondered where it comes from. Now everything's clear 😊

[mrdoob]

Hmm... I wonder if the fix should be in the renderer instead. Like logging a warning when a Mesh is passed with a undefined geometry?

[Mugen87]

I think mesh.geometry is not undefined but it's just an empty instance of BufferGeometry. Simplified Demo: http://jsfiddle.net/akmcv7Lh/325/

That's actually an ongoing issue since it's not clear to me what three.js considers as a "valid" BufferGeometry. A geometry without attributes causes warnings or errors in some situations (e.g. #13601). I suggest we try to change the code in the renderer so it does not complain when processing such a BufferGeometry.

[Mugen87]

I vote to merge this PR in order to get rid of that annoying warning. We can still change the renderer in later PRs.

[mrdoob]

Thanks!