I have a thought. Based on discussion and reading the wiki, it sounds like the output node of shader node trees will have inputs for both a bxdf and a color, similar to this image from Matt's wiki page: http://wiki.blender.org/uploads/0/03/Shadsys_node_passes.png
For global illumination, I get the impression that the renderer will use the bxdf output for both sampling and evaluation, and it would only use the color output for direct-to-screen shading. But I wonder if it wouldn't make sense to instead only use the bxdf for sampling, and use the color for all evalulation. And it could still fall back to the bxdf if there is nothing hooked up to the color. This would allow more flexibility in designing shaders that work globally (i.e. not just shading directly to the screen). For example, if I wanted to implement a Lommel-Seeliger brdf via math nodes, I could do so. Then I could separately construct a sampler for it by mixing bxdf's similar to the Lommel-Seeliger brdf, and plug it into the bxdf output. It's an advanced use-case, and most people could ignore it by just mixing bxdf's and ignoring the color output. But it seems valuable for doing more advanced things than just material mixing. (It would also, perhaps, be interesting for constructing physically implausible shaders and having them interact with GI. Like toon shaders showing up in glossy reflections/refractions.) --Nathan V On Tue, Dec 1, 2009 at 5:06 PM, Brecht Van Lommel <bre...@blender.org> wrote: > Hi, > > After discussion with Matt and Nathan, I've revised the proposal, I > think it's much clearer now, and also more ambitious. There's still > various things to be worked out in more detail and mockups for UI to > be made. But I think we now have a design that solves the BXDF/node > interaction and the texture stack questions. > http://wiki.blender.org/index.php/BlenderDev/ShadingSystem > > Brecht. > _______________________________________________ > Bf-committers mailing list > Bf-committers@blender.org > http://lists.blender.org/mailman/listinfo/bf-committers > _______________________________________________ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers