I need to render a lot of quick turntables via PDG and ideally I'd like to use the opengl ROP to do it. That was working well, but I've stumbled onto a problem -- some of the assets are entirely concave (i.e. the interiors of rooms), in which you want to see a turntable but *not* the outward faces -- just the content inside the room.

This works fine in a flipbook with the display settings "Remove Backfaces" flag enabled, but the opengl ROP seems to ignore the OBJ level setting on the Render/Geometry tab which I imagine is supposed to accomplish the same goal. Mantra does recognize that OBJ flag and renders sans-backfaces but it's way too slow for something meant to knock out turntables all day.

Does anyone have any thoughts on what I could be missing here? Or is it simply impossible to use the opengl ROP for this purpose?

Thanks!

I couldn't find a way for this to work either!
But you can delete faces which is away from camera by VEX or use Group SOP with writing address of your camera in Backface from parameter in Keep by Normal section thereafter you can use a Blast SOP to delete them.
Hope this helps!

Yuck. I'd thought of a similar hack but really hoping it doesn't come to that. These assets are very high polycount, the blast operation is almost as slow as just dropping the mantra samples and probably more unstable.

Oh well, thanks for the idea!

Another way is to add vm_geometrygroup parameter from Edit Rendering Parameters and pass your group of primitives which you want to visible to the renderer...

N-G
Another way is to add vm_geometrygroup parameter from Edit Rendering Parameters and pass your group of primitives which you want to visible to the renderer...

Thanks, I didn't know about that trick. Is there anything to this approach other than installing the parm on the ROP and populating it with the appropriate prim group? It doesn't seem to do anything on the opengl ROP so I'm wondering if it's specifically for Mantra.