Kaprolactam 1 Posted January 21, 2020 (edited) Hey everyone, I've got a question that, even after lengthy research still has me stumped. I've got a pyro fireball and a ground geometry that reflects the fireball. The simple question is: How do I set up the ground plane and its material so it reflects the fireball, including alpha, and just gives me a black alpha where there is nothing to reflect? I've tried to force it to phantom, that just makes it invisible, other, somewhat hacky workarounds like this one are rather old and in the SHOP context. Nothing I tried seems to work. When I'm working in 3ds max and Vray, I use this technique all the time (vray object properties -> reflection/refraction matte), I just don't get how this can be this much of a faff in Houdini, so I'm probably missing something pretty obvious. I'm grateful for any and all help, thanks in advance! Edited January 21, 2020 by Kaprolactam Share this post Link to post Share on other sites
TobyGaines 10 Posted January 27, 2020 I'm sure you can build a shader to do that - I haven't figured it out myself - what I usually do for that is just apply a white constant shader to the subject and use the reflection as the alpha channel in comp Share this post Link to post Share on other sites
