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Object with 2+ materials applied cannot use displacement
Posted: Tue Jul 03, 2012 2:43 am
by itsallgoode9
An object has two or more materials applied to it...if any material has a displacement map, the render will crash during pre-processing phase. Using Maxwell Render 2.7 on Win x64
Can anybody verify this?
Re: Object with 2+ materials applied cannot use displacement
Posted: Tue Jul 03, 2012 7:39 am
by Hervé
confirmed..
h/
Re: Object with 2+ materials applied cannot use displacement
Posted: Tue Jul 03, 2012 8:51 pm
by simmsimaging
I am having instant crashing with a single material and two BSDF layers. Same thing, or do you guys mean a multi sub-object material kinda thing?
Re: Object with 2+ materials applied cannot use displacement
Posted: Wed Jul 04, 2012 3:29 am
by Mihai
Yup, the bug happens with displacement applied only to part of an object.
Re: Object with 2+ materials applied cannot use displacement
Posted: Wed Jul 04, 2012 11:36 am
by tom
This is a limitation.
Re: Object with 2+ materials applied cannot use displacement
Posted: Thu Jul 05, 2012 11:24 am
by lebulb
I have the same problem with two of my projects
tom wrote:This is a limitation.
In both cases, I use sss + displacement and I cant do otherwise. (closed volume + complex UV mapping)
This will be resolved?
Re: Object with 2+ materials applied cannot use displacement
Posted: Thu Jul 05, 2012 1:03 pm
by JDHill
tom wrote:This is a limitation.
Please explain, because there was no such limitation in 2.6.10.
Re: Object with 2+ materials applied cannot use displacement
Posted: Thu Jul 05, 2012 5:50 pm
by tom
The pretesselated displacement will not work if the object has multiple materials assigned to different triangle groups (in other words, if the displacement is assigned to some part of the object). It's the limitation of tesselation algorithm unable to create unweld vertices on neighbor edges. But, it shouldn't crash and suggest "on-the-fly" method.
-Edit: I may be misleading and maybe this is not a limitation anymore. Because, now I saw my own internal bug report which I closed myself some time ago. 
We definitely need to check it because, even on-the-fly is now crashing...
Re: Object with 2+ materials applied cannot use displacement
Posted: Thu Jul 05, 2012 6:11 pm
by JDHill
Yes, I am very sure that this is a 2.7 bug involving displacement vs. triangle groups: both pretess and on-the-fly work fine in 2.6.10, and both crash in 2.7.
Coming from SketchUp, almost every mesh ends up using triangle groups; SketchUp users who read this topic should see
this post for a tiny Ruby script that helps to remove per-face material assignments, so that they do not override a displacement material assigned at the group level. Without that, it can be difficult (not to mention tedious) to remove every front and back material from all group faces.
Re: Object with 2+ materials applied cannot use displacement
Posted: Mon Jul 09, 2012 8:48 pm
by Bubbaloo
I confirm, it used to work in 2.6, now it makes my scenes crash.
Re: Object with 2+ materials applied cannot use displacement
Posted: Fri Jul 27, 2012 12:33 pm
by tom
Fixed in 2.7.10.0