VrayMtl refraction reset bug 3.6?

[snivlem]

Hi,

Sorry for the amount of threads recently but stumbling across a few bugs with this latest project.

Here's a really odd one and it's reproducible.

Basically I have a glass material, which renders great (see attachement 1).

However when one plugs in a 100% white ramp to the opacity slot, it seems something permanently resets on the VRayMtl.

You can see it renders differently and the swatch is wrong as well. The only change between the two images was attaching a ramp to the opacity slot, then disconnecting it.

It now appears that the VRayMtl is broken as it never renders as it originally was before the ramp was conencted to the opacity slot.

[yolov]

It doesn't show clearly from your second screenshot, but if after disconnecting the ramp the "refraction" slot goes black (so it's black both in the attribute editor and in the render) could you look into what color is shown in the attribute editor *while* the ramp is connected? (see attachment).

If it's black, then it would be normal, here's why: If you've connected a default ramp, the first position of the ramp is black and this color is passed as a "value" to the color picker while the connection is active. While the connection is active, whatever texture is connected will be use, but once disconnected, whatever "average" value was being shown in this slot will be used from then on. It's basically something that Maya does and it does it for most if not all slots.

[snivlem]

That is correct, but the issue is the shader permanently changes after the disconnection occurs with the opacity slot.
Even if the swatch is set to 100% white, the material will never render the same as it was before the connection was ever made.

It sounds strange, I know, but this is reproducible on my end using 3.6 public release and Maya 2018x64.

Edit: Your screenshot shows the connection to refraction but the bug happens when the connection is made to the opacity slot. It appears to change the refraction and I daresay the whole bug might have been introduced with the new opacity methods.

[snivlem]

Ok, I will send a PM with a screencast showing the bug. It's pretty significant and cost me quite a bit of time to figure it out because all the glass in my scene was wrong and couldn't work out why!

[yolov]

I get it now, but I still can't reproduce it, sorry for the confusion. I've sent another PM.

[snivlem]

Oka, done!