on before render event

[guidocalvano]

It would be handy to have this event:
https://threejs.org/docs/#Object3D.onBeforeRender

I want to use it for rendering infinite planes and infinite lines, by clipping them with the visible volume of the camera, and to render custom grids and axes that automatically calculate the size of grid lines and spacing grid labels based on the distance of the camera.

I would not mind helping implement this if I had some pointers where to start.