Cycles: Add support for light groups

Light groups are a type of pass that only contains lighting from a subset of light sources.
They are created in the View layer, and light sources (lamps, objects with emissive materials
and/or the environment) can be assigned to a group.

Currently, each light group ends up generating its own version of the Combined pass.
In the future, additional types of passes (e.g. shadowcatcher) might be getting their own
per-lightgroup versions.

The lightgroup creation and assignment is not Cycles-specific, so Eevee or external render
engines could make use of it in the future.

Note that Lightgroups are identified by their name - therefore, the name of the Lightgroup
in the View Layer and the name that's set in an object's settings must match for it to be
included.
Currently, changing a Lightgroup's name does not update objects - this is planned for the
future, along with other features such as denoising for light groups and viewing them in
preview renders.

Original patch by Alex Fuller (@mistaed), with some polishing by Lukas Stockner (@lukasstockner97).

Differential Revision: https://developer.blender.org/D12871

1 files changed, 1 insertions, 1 deletions

diff --git a/intern/cycles/kernel/integrator/shade_light.h b/intern/cycles/kernel/integrator/shade_light.h
index 4a519a76ed0..be926c78439 100644
--- a/intern/cycles/kernel/integrator/shade_light.h
+++ b/intern/cycles/kernel/integrator/shade_light.h
@@ -78,7 +78,7 @@ ccl_device_inline void integrate_light(KernelGlobals kg,
 
   /* Write to render buffer. */
   const float3 throughput = INTEGRATOR_STATE(state, path, throughput);
-  kernel_accum_emission(kg, state, throughput * light_eval, render_buffer);
+  kernel_accum_emission(kg, state, throughput * light_eval, render_buffer, ls.group);
 }
 
 ccl_device void integrator_shade_light(KernelGlobals kg,