Render time boolean with volumetric scattering bug

[Place]

Hi All,

searching on the forum I didn't find a similar report so I hope it's not a duplicate:

Using corona distance map in a render time boolean, if a material uses volumetric scattering, with absortion color different from pure white, it doesn't work as expected.
If needed I'll upload the scene.
Tested on Max 16/19 and corona 3/4.

Thanks,
Manuel

edit: changed image

[Frood]

I think the issue is not the distance map. Generally when using opacity (or an animated visibility track), the object will fade but not the volumetric part. Same should happen if you just use opacity other than 1 in the material. You can try to control absorption color with the same distance node ('Box002') in another distance map and blend between your absorption color and white there.


Good Luck

[Place]

Thank you Frood, it works!
But don't you consider a bug that the volumetric part doesn't fade using opacity?
Don't mind, I just read your statement in the link you provided.
But I don't get why it works in this way

[maru]

But I don't get why it works in this way

This is because to Corona the object's surface is a different thing, and the object's volume is a different thing.
Surface is diffuse color, reflectivity, opacity, etc.
Volume is absorption and scattering (and emission in case of CoronaVolumeMtl).

With your render time boolean you are affecting the opacity of the object you are cutting, so its surface becomes transparent, but the volume becomes intact.
Like Frood said, you can use your CDistance map to affect the object's absorption - i.e. set that object's absorption to white (=fully transparent) wherever that object's volume is inside your cutter object.

Hope that clarifies what's going on.

[Place]

It does, thank you Maru