This adds clamping at the light combine stage for both direct
and indirect light.
This allows for clamping direct and indirect light separately.
While direct light clamping might not be very desirable in
EEVEE, it might be wanted to reduce the flickering from distant
shiny bumpy surfaces, or for artistic reason.
This happens after applying the BSDF throughput just like cycles.
This is done in order to minimize the performance impact and
allows to split the clamp for direct light and indirect light.
The indirect light clamp value is still used in the ray-tracing
pipeline to clamp the ray intensity. But this differs from cycles
as we clamp the ray without the BSDF throughput here. Sphere probe
have the same issues. Some more energy loss is expected compared
to the direct light clamp.
Note that we still clamp the indirect light after applying BSDF
in case the BSDF is scaling the energy up above the threshold.
This also corrects the clamping for volume that now clamps after
applying the scattering term.
Also adds clamping to volume indirect lighting.
Since we use light probe volumes for both surface and volume
indirect lighting, we need to clamp them at sampling time.
Pull Request: https://projects.blender.org/blender/blender/pulls/120866
d44ee7bf11