I'm trying to get composure up and running. Most things are figured out apart from one.

I have a mesh in a scene, made from photogrammetry of the scene, and it's aligned to the camera (and therefore the video I'm using) by an animated camera track. I want to add in some CG geometry and have it be able to be occluded by the scene geometry, so when I comp it over the video it will look like it's being occuluded by object in the video.

To do this I need the scene geometry to occlude the CG geometry, but remain invisible. Ie I need the scene geo to write to the depth buffer only. Any idea how to acheive this? I'm sure there are a few methods. Ideally the method would only involve mods to the material of the scene geo, not the CG geo (to make is simpler to add additional CG geo).

There is an element in Composure called Depth Comp which I thing is meant to facilitate this but it's not playing ball, so I'm looking ofr another way.