Light material in Ray-Switch

[mraw]

I have a Light Material plugged in the GI-slot. A black material is in the direct visible-slot.
However the LightMaterial is directly visible. Only when I uncheck 'Emit Light' the black material is visible.
Is this a bug or is my understanding of the rayswitch limited?
thanks.

[romullus]

There's been similar report recently: https://forum.corona-renderer.com/index.php/topic,10853.0.html
Lets wait for devs answer. I'll move topic to bug reporting board, if there will be no response.

[mraw]

Ok. Many thanks, Romullus.

[Juraj]

This is nothing recent, it worked like that when I used it year ago.

I absolutely do not get the idea behind Rayswitch, works polar to how it's implemented in Vray. Instead of using override for what I need I have to separate it into all slots.

The Lightmaterial use inside was so painful I never used it again.

[mraw]

It is working with a standard material with self illumination turned on. But this gives me pretty noisy renders.
So I went for the Light Material in the GI-Slot.
When I uncheck the 'Emit Light' checkbox: What I get is equivalent to SelfIllumination?

[maru]

I will try to get back with some explanations tomorrow, but now I can only post this for info about differences between self illumination and light mtl:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000515603

[mraw]

Thanks. I know this link and the selfIllum. is by far not the brightest or main light in the scene.
But I bumped the value up, just to see a little bit of spill light in the nearer environment.

[mraw]

Sorry for bumping this thread up. But I really have to know if this behaviour of Light material in GI-slot is faulty.
And if yes: How can it be fixed? Is there a workaround?

[maru]

Just to make sure I understand everything - the idea is to make a light using light mtl that will glow (illuminate scene), but will appear as, for example, black sphere?

I didn't find a good way to do it. It looks like what we see directly is actually the GI component of the light material.

A silly workaround is to disable light's "visible directly" option (in reflections/refractions too if needed), duplicated it, assign black material to the duplicate, and exclude the duplicate from light's influence.

[mraw]

An interesting approach, thanks. But to be honest I can't reproduce it. Silly me.
Let me describe your suggestion with my own words.
- you disable 'visible directly' in the properties of the light material.
- clone the object and assign black shader
- exclude the clone from the light.

correct? thanks

[maru]

Yes, that it exactly what I did. Does it produce a different result for you?

[mraw]

Yes, because the cloned teapot occupies exactly the same space?
it seems to confuse Max what's behind and what to show/render.

[maru]

I don't get it. Your glowing teapot is still visible despite the fact that you unchecked "visible directly". Are you sure that you have right materials applied?

[romullus]

That's hardly a workaround if it's requires to fiddle with geometry. And it's very impractical. maru, can you tell us if such Rayswitch behaviour is by design, some limitation or simply a bug?

[mraw]

I don't think this workaround is something I want to do in production. But it is a good approach finding out
what's going on.
I'm still not able to reproduce it- maybe some misconception on my side?
Without trying to reproduce the 'exclude-copy'-thing:
capture1. Shouldn't there be a black teapot in the viewport?
capture2. You could see 'vis.dir.' checkbox disabled.  The preview render of the material works, but
not in the viewport and not in the render.