C4D's Multipass system can save mattes based on objects.
But often it would be much better to save mattes based on
materials / shaders so every object which has a specific material
will be saved into an object buffer / matte. That's where the
Smart Shaders plugin comes in. In the next update (coming this week)
it will include a so called Multipass Shader, with this Shader one can now:
1. Save mattes based on materials or shaders
2. Object buffers / mattes name resolve later in the filename.
3. Save RGB mattes, so three mattes within one file.
4. Output Shaders as mattes, for detailed compositing work.
Everyone involved in a Multipass workflow will exactly know what this means,
a big time saver in handling multipasses :-)
Thanks very much to Paul Everett from tools4d.com.