Cycles; massive shading failures with glass node mixing, whiteouts and blackouts. #40964

New Issue

Adam Friesen · 2014-07-06T04:37:57+02:00

Adam Friesen commented

2014-07-06 04:37:57 +02:00

System Information
Win7 64 bit, Ivy Bridge i7 CPU, ATI 7xxx GPU, 16 gigs of RAM

Blender Version
Broken: 5aec61f
Worked: Any pre-2.71 release build.

Short description of error
As of the last month (perhaps since the new importance sampling commit), the user can no longer mix two or more glass nodes together for any purpose without getting either a massive blowout or a total blackout. It seems glass shading in general is crippled now for anything but basic uses (which is using just one glass node). I'd hate to contribute to the ever growing bug list (do we have anyone making these a priority right now without Brecht?), but one more for the pile anyway.

Exact steps for others to reproduce the error
Open the attached .blend and press F12, notice the white out when two glass nodes are being mixed while a blackout occurs when all four are mixed. This only occurs when the roughness value is above 1.
Bugged_glass.blend

System Information Win7 64 bit, Ivy Bridge i7 CPU, ATI 7xxx GPU, 16 gigs of RAM Blender Version Broken: 5aec61f Worked: Any pre-2.71 release build. **Short description of error** As of the last month (perhaps since the new importance sampling commit), the user can no longer mix two or more glass nodes together for any purpose without getting either a massive blowout or a total blackout. It seems glass shading in general is crippled now for anything but basic uses (which is using just one glass node). I'd hate to contribute to the ever growing bug list (do we have anyone making these a priority right now without Brecht?), but one more for the pile anyway. **Exact steps for others to reproduce the error** Open the attached .blend and press F12, notice the white out when two glass nodes are being mixed while a blackout occurs when all four are mixed. This only occurs when the roughness value is above 1. [Bugged_glass.blend](https://archive.blender.org/developer/F96812/Bugged_glass.blend)

Adam Friesen commented

2014-07-06 04:37:57 +02:00

Changed status to: 'Open'

Adam Friesen commented

2014-07-06 04:37:57 +02:00

Added subscriber: @Ace_Dragon

Adam Friesen commented

2014-07-06 04:54:15 +02:00

A possible thing that might help.

It appears that the root cause for both this and the refraction shader bug I reported a few days ago could be one and the same, and that root cause would likely be in whatever code came in when the importance sampling for glossy shading was overhauled.

So fixing one of them might fix the other, but that comes with the disclaimer that I don't know for sure how the code works.

A possible thing that might help. It appears that the root cause for both this and the refraction shader bug I reported a few days ago could be one and the same, and that root cause would likely be in whatever code came in when the importance sampling for glossy shading was overhauled. So fixing one of them might fix the other, but that comes with the disclaimer that I don't know for sure how the code works.

Adam Friesen commented

2014-07-06 05:38:04 +02:00

Oh, fun fact, I just found out that Glass is now completely broken when OSL shading is turned on in post 2.71 builds (the refraction component just renders as black). Switch to OSL in this file and even stripping the node setup down to a single Glass BSDF won't work.

So if you're reliant on custom OSL shading, Cycles is pretty much unusable for the time being in many situations.

Oh, fun fact, I just found out that Glass is now completely broken when OSL shading is turned on in post 2.71 builds (the refraction component just renders as black). Switch to OSL in this file and even stripping the node setup down to a single Glass BSDF won't work. So if you're reliant on custom OSL shading, Cycles is pretty much unusable for the time being in many situations.

Thomas Dinges commented

2014-07-06 11:59:44 +02:00

Added subscriber: @ThomasDinges