Adding a texture to a shader so the alpha works with renderman RIS

[richard...@gmail.com]

Hi, I'm really new at renderman, and I can't for the life of me figure out how you're supposed to get a alpha texture on a renderman RIS shader. This is for Renderman 19 in maya 2015.

Example: Tree leaves. I'm using geo planes in maya, then adding textures to those planes of the leaves with an alpha channel. Rendering with Renderman gives me black where the alpha is.

Does anyone know how to use alphas in the new Renderman 19.

Thank you very much for your time.

Cheers.

Richard

[L. Onokhov]

I think most RIS base materials should have appropriate parameters for opacity.
For example tooltip on PxrDisney.presence attribute says you should connect your mask to it. I don't think any of them support coloured opacity, it does not
play nice with 'plausible' shading.

[Bo Schwarzstein]

In the RSL there is no RGBA type but only the color or float, so you have to add another paraemeter for the alpha or opacity, and call mix() to blend the two colors by the weight.

[Richard Gillies]

Thank you very much. That worked like a charm.