Laser not visible in volume

[syhrdrjrt]

Every time I try something with lasers and glass in Luxcore I go crazy after a short time. This time I have a prism, three lasers and an inner and outer volume. The lasers are always visible outside the prism, but inside ONLY if you select rough glass. No other settings have been changed. Such absolutely strange errors always drive me crazy after a short time when I try to do something. Maybe someone knows how to fix this

[Dade]

They are called SDS (Specular-Diffuse-Specular) paths and they require a very specific algorithm to be able to render them. You need to enable caustic cache (on volumes) to be able to see them.

By using rough glass you transform SDS paths in GDG (Glossy-Diffuse-Glossy) paths and they can be rendered by BiDir or with Path+Light tracing enabled.

[syhrdrjrt]

Thanks for the reply, wouldn't it be possible to give a very tiny base roughness to the normal glass as well, making everything easier? Also more intuitive?

[Sharlybg]

They are called SDS (Specular-Diffuse-Specular) paths and they require a very specific algorithm to be able to render them. You need to enable caustic cache (on volumes) to be able to see them.

By using rough glass you transform SDS paths in GDG (Glossy-Diffuse-Glossy) paths and they can be rendered by BiDir or with Path+Light tracing enabled.

Never had this in Mind.

[Dade]

wouldn't it be possible to give a very tiny base roughness to the normal glass as well, making everything easier? Also more intuitive?

It wouldn't be glass anymore but rough glass

[syhrdrjrt]

Yes, but with dispersion. Is there such a thing as perfectly smooth glass? Isn't there always at least a bit of roughness that could then be used for GDG paths?
I did some more tests with the same settings and mixed the normal glass shader (+inner and outer volume) with other materials, and everything looks more realistic than the standard shader

standardGlass

glass glossy mix (shouldn't the laser be visible here, since it would be GDG paths?)

glass metal mix