...
The above LPE will render a beauty of the scene lit by the lights tagged as "key". Replacing 'key' with another group would render the other group as specified like 'rim' or maybe you need the HDRI as 'environment' separated into an AOV.
If you needed more than a single group, you could use the pipe to say "or" another group or groups.
| Code Block |
|---|
lpe:C<[RT][DS]>*[<L.('key'|'fill')>O]
Shorthand
lpe:C<..>*[<L.('key'|'fill')>O] |
Of course you can also ask for other data from a path to a light group like indirect diffuse reflection (usually known as indirect lighting) for later scaling in compositing.
| Code Block |
|---|
lpe:C<RD>+[<L.('key'|'fill')>O] |
Now you can output whatever you need based on light groups!