I'm trying to render particles with an alpha channel with the Hardware Render Buffer. I'm rendering the frames as targas. I have set the Alpha Source in the Hardware Render Buffer attributes to both Luminance and Hardware Alpha with no success. I have turned the Geometry Mask on and off with no success.
I'm not sure what I am doing wrong. According to the docs and my colleagues at work, I should be able to set the Alpha Source to Luminance and get an alpha channel. However, when I bring the targa sequence into After Effects and view the alpha channel, I just see a white frame. I did manage to render some geometry as a targa sequence with an alpha channel using the Maya Software renderer. Any advice?
Have you tried using the Hardware Render instead of the hardware render buffer? Usually more options in there. It's been awhile since i've used the HW render buffer, but i remember it being reallly fininky about the way textures feed into the alpha. What you might do if all else fails is render two passes, one with the color pass, the other with just a alpha(bw images) and then comp it in post.