Allow configuring the scaling rate In THREE.TransformControls

[blaise-io]

I have a simple editor for 3D models using three.js. This is my camera:

new THREE.PerspectiveCamera(30, window.innerWidth / window.innerHeight, 0.01, 10);

And this is my mesh's geometry:

new THREE.BoxGeometry(0.3, 0.3, 0.3);

I'm using THREE.TransformControls to scale the mesh.

Scaling works perfectly fine when meshes have units ~ 100, but when an object is between 0 and 1, scaling is very slow. With slow, I mean that when you drag the scale slider half the canvas size, the mesh increases or decreases only a few percentages in size. I don't have this problem with other TransformControls modes.

This is because there's a the magic number 50 in the code that translates mouse movement to scale.

Can we make this number configurable, and/or make it use a sane default based on mesh size or camera?

JSFiddle demonstrating slow scaling

[mrdoob]

Sounds good to me. Would be nice to have a paremeter for it.
/ping @arodic

[sandromartis]

There was pull request that resolved this issue by taking the current object scale into account. (#8582)
This makes the scaling rate stay the same for different sizes of objects.

But I still think it would be nice to have a parameter to change the "sensitivity" of the overall scaling.
I added something like that in our version of the transform controls because the scaling was too sensitive for us.

I could probably make a pull request with those changes.