grouping nodes changes rendering results (introduces artifacts) #35847

New Issue

Blends Nicely · 2013-06-23T09:37:13+02:00

Blends Nicely commented

2013-06-23 09:37:13 +02:00

%%%--- Operating System, Graphics card ---
Linux 3.8.13-gentoo amd64
CPU: Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz
GPU: NVIDIA Corporation GK104 [GeForce GTX 670] (rev a1)

- Blender version with error, and version that worked ---

currently I only have access to 1.66 and 1.67b - both are affected.

- Short description of error ---

Using a material containing only one Glass Shader works fine. Putting this single glass shader into a group (Ctrl+G) destroys the result.

- Steps for others to reproduce the error (preferably based on attached .blend file) ---

switch 3D view to "rendered" and switch material between "glass ok" and "glass not ok".
The CPU and GPU results are the same for "glass ok", but for "glass not ok" they differ (no reflections for GPU version) - plus: the glass is black..

%%%

%%%--- Operating System, Graphics card --- Linux 3.8.13-gentoo amd64 CPU: Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz GPU: NVIDIA Corporation GK104 [GeForce GTX 670] (rev a1) - Blender version with error, and version that worked --- currently I only have access to 1.66 and 1.67b - both are affected. - Short description of error --- Using a material containing only one Glass Shader works fine. Putting this single glass shader into a group (Ctrl+G) destroys the result. - Steps for others to reproduce the error (preferably based on attached .blend file) --- switch 3D view to "rendered" and switch material between "glass ok" and "glass not ok". The CPU and GPU results are the same for "glass ok", but for "glass not ok" they differ (no reflections for GPU version) - plus: the glass is black.. %%%

Blends Nicely commented

2013-06-23 09:37:13 +02:00

Changed status to: 'Open'

Blends Nicely commented

2013-06-23 09:42:53 +02:00

%%%r57660 is also affected%%%

Lukas Tönne commented

2013-06-23 16:25:32 +02:00

%%%The reason for this is that the Normal input is included (automatically) in the node group. Cycles uses a bit of annoying trickery to replace the usual constant input value of normal inputs by the variable default surface normal in most nodes, so that you don't have to explicitly connect it to the geometry nodes to get usable results.

However, this does not happen with generic group node vector inputs, since this is just a "meaningless" vector for which the default constant value is used. So when wrapping a node group around a glass node or similar this vector input feature gets lost. A simple solution is to just exclude the normal from the group node inputs (see the attached bug_fixed.blend).

To solve this issue in the long run and support automatic default normal inputs in cycles there could perhaps be a different vector type for such specialized sockets. Any socket with the normal vector semantics would then be exposed as such in group and also get a the standard surface normal if unconnected.%%%

%%%The reason for this is that the Normal input is included (automatically) in the node group. Cycles uses a bit of annoying trickery to replace the usual constant input value of normal inputs by the variable default surface normal in most nodes, so that you don't have to explicitly connect it to the geometry nodes to get usable results. However, this does not happen with generic group node vector inputs, since this is just a "meaningless" vector for which the default constant value is used. So when wrapping a node group around a glass node or similar this vector input feature gets lost. A simple solution is to just exclude the normal from the group node inputs (see the attached bug_fixed.blend). To solve this issue in the long run and support automatic default normal inputs in cycles there could perhaps be a different vector type for such specialized sockets. Any socket with the normal vector semantics would then be exposed as such in group and also get a the standard surface normal if unconnected.%%%

Blends Nicely commented

2013-06-23 16:47:46 +02:00

%%%good finding! A usable work-around. Thank you!
%%%

%%%good finding! A usable work-around. Thank you! %%%

Brecht Van Lommel commented

2013-06-23 21:24:51 +02:00

%%%Fix in svn now, both in the UI to hide the vector value by default when exposing such a socket in a group, and in cycles to ignore any values from the group sockets in this particular case.%%%

Brecht Van Lommel commented

2013-06-23 21:24:51 +02:00

Changed status from 'Open' to: 'Resolved'

Brecht Van Lommel closed this issue

2013-06-23 21:24:51 +02:00

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grouping nodes changes rendering results (introduces artifacts) #35847