rendering occluded objects

I am rendering an object on another object… I need the object underneath to render
just as a matte, occluding the object over it, but not creating an alpha, and not
rendering in the render pass. An example is a rider on a horse, I just want to
render the rider, but have the far side, hidden by the horse, not render.

Thx

Hi, you’ve probably figured this out already but since i just had to do the same thing i thought i’d respond anyway - in 2.6x (and i assume 2.5) you can turn on transparency in the object’s material, select Mask and turn the Alpha to 0. This did the trick for me.

I also just found a reference to an ‘ENV’ button in earlier versions of Blender which apparently does the same thing, but not having anything earlier installed i can’t really comment.