Two well known luxcore problems.

[Dade]

Have you done a full rebuild ("make clean") ?

[chuchur]

Yes, sure. After rerunning cmake everything works fine again. I haven't fetched for a long time.

[Martini]

From what I can guess/observe by looking at the render result, it looks like the transmission is not present in the rough glass, and perhaps the normals are a bit weird also.

Looks like roughglass is working spectacularly well in latest build (sorry for not testing for a few days)

LuxCore roughglass

Thanks Dade

[Sharlybg]

Do you mean that the lastest Blendluxcore daily build have it.

[Martini]

Do you mean that the lastest Blendluxcore daily build have it.

I only downloaded the standalone binaries from LuxCoreRender, but yes, the same ones should be included automatically in daily builds of BlendLuxCore as well.

[Sharlybg]

On my side wit lasest blendluxcore build the darkening issue is still there :

rough_glass.blend

(988.33 KiB) Downloaded 110 times

I don't how it is possible to solve it without a multiscatter glass model.Cycles solve it this way of course. the non scattering version aka ggx give same dark result as lux. And you have to put it in multi scattering ggx for this to work.

[kintuX]

Naive thought here...

Would it be possible to get a trick like "NO Energy loss" (no lightloss, no falloff or best - customizable control for light falloff) or switch to affect specular & glossy materials, so in principal, a user could create rough glass as bright as Env. light?

[epilectrolytics]

Would it be possible to get a trick like "NO Energy loss"

Agreed, in Cycles you can configure a glass material (using "ray depth" node or sth.) that does not return black after the last bounce but instead switches to transparent and thus guarantees bright glass appearance.
If this could be somehow coded into Lux glass shader maybe the problem were solved?

[Sharlybg]

Why go this way if a more accurate less tricky way exist (multi scattering rough glass) ?

[epilectrolytics]

Why go this way if a more accurate less tricky way exist (multi scattering rough glass) ?

The tricky thing is probably easier to implement (though I don't know really), and maybe rendering faster?
If there is a major overhaul of LuxCore via Cuda-C++ with all new materials before us it makes no sense to waste effort updating old materials.
If the Cuda-C++ thing is still years away I'd agree that it would be best to integrate multi scattering into rough glass now, because we need a solution for this.