Corona 12 glass material problem

[Anton Maksymov]

After updating to Corona 12, my glass materials started behaving strangely. The previous settings, which worked perfectly, are now giving completely different results. Specifically, I'm referring to Volumetric Scattering as well as the front and back parts of the glass (textured glass at the back and smooth at the front).

Volumetric Scattering is now giving the glass a lot of color without any changes to the settings.

Regarding the texture of the glass: I use a Multi/Sub-Object map to apply different materials to different polygons. That is, for a 5mm thick box, one material is applied to the front (smooth glass) and another to the back (textured). In version 11, everything worked perfectly, but now the back part of the glass just doesn't render (examples of images below).

[TomG]

Might be related to "Added option to distinguish media based on their material (e.g., two intersecting objects with the same material will be now considered as a single volume). This is automatically active for new scenes." ? This could be changing the interpreted thickness of the overlapping objects, thus increasing absorption effects? Though sounds like you aren't using different objects in the example, just two variations of the material front and back one which has a bump and the other does not, but not 100% clear on that.

What version did you update from btw, Corona 11? What happens if you just apply one material rather than a front and back set up?

[Anton Maksymov]

Might be related to "Added option to distinguish media based on their material (e.g., two intersecting objects with the same material will be now considered as a single volume). This is automatically active for new scenes." ? This could be changing the interpreted thickness of the overlapping objects, thus increasing absorption effects? Though sounds like you aren't using different objects in the example, just two variations of the material front and back one which has a bump and the other does not, but not 100% clear on that.

What version did you update from btw, Corona 11? What happens if you just apply one material rather than a front and back set up?

It's a single box with two materials applied: one smooth and one bumpy. In the example below, the same object is rotated 180 degrees. The front and edges use material 1, while the back uses material 2. This is how the glass material works now, which is very inconvenient and hinders my work.

I never thought I would need to revert to a previous version.

[Anton Maksymov]

Another example of how the glass material has changed from Corona 11 to Corona 12.

[Anton Maksymov]

What version did you update from btw, Corona 11? What happens if you just apply one material rather than a front and back set up?

Yes, from Corona 11 to Corona 12.
 Here's what happens if you use just one material (screenshot below).

[CharlyRT]

mmmm could it be something related to max ray depth? Could you check the value, a couple of versions ago someone ask me why his glass material changed from one version to other and that was it, it might help to check it

[Anton Maksymov]

mmmm could it be something related to max ray depth? Could you check the value, a couple of versions ago someone ask me why his glass material changed from one version to other and that was it, it might help to check it

Thank you for your response, but unfortunately, it didn't help.

[Aram Avetisyan]

Hi,

From what I see, it may be scaling issue - for the whole scene or for the absorption distances. This might have happened when opening scene and not adopting its scale units.
If Corona 12 is too saturated with color, try checking the absoprtion/volumetric distances, increase them by, say, 10 and see if you get consistent results with Corona 11.

[Anton Maksymov]

Hi,

From what I see, it may be scaling issue - for the whole scene or for the absorption distances. This might have happened when opening scene and not adopting its scale units.
If Corona 12 is too saturated with color, try checking the absoprtion/volumetric distances, increase them by, say, 10 and see if you get consistent results with Corona 11.

Hi, thanks for your response.

This is the same scene, with the same units of measurement. I rule out a scaling issue because everything returns to normal if I use one material on the object instead of multiple (Multi/Sub-Object map). So, I think the problem is specifically with having multiple glass materials on one object. This issue arises only with glass materials because when I apply a mirror material to the back side, everything works fine.

[maru]

(this is being handled in support ticket #266379)

[kkinross]

I am having a similar issue with a glass cup. I have multi/sub object material on the cup where the out side is one glass material (to make a condensation effect), and a more clear glass material to the top/bottom/inside polys. It looks quite different in Corona 12. This is a huge issue for us as I will now have to revert all of our CGI computers back to version 11.

[Aram Avetisyan]

Hi,

Enabled development/experimental menu and try enabling/disabling this option.
See if it improves/fixes the look.