Unable to create different scales for instances

[marcelpi]

Hi there,

I've been trying to no avail to have the instances of an instancedMesh be of different sizes/scales.
The code is going through the instanceMatrix and reads the transformation matrix for each instance, modifies its scale and then updates the instanceMatrix. It's done inside the useEffect() and this should make balls of different sizes.

But for some reason, it's not working. Any idea why and what I need to do to make it work?
I'm trying to have balls of different sizes collide. Right now they are all identical and there's no variation.

Any help would be appreciated. Thanks.

Here's the sandbox: https://codesandbox.io/s/ballpit-forked-olywwy