OSL bug? (interior shader) #56804

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Phil Stopford · 2018-09-14T17:30:40+02:00

Phil Stopford commented

2018-09-14 17:30:40 +02:00

System Information
Win 10 Pro, 6 GB GTX 1060

Blender Version
Broken: 2.79b and master
Worked: (optional)

Short description of error
For the attached OSL script (interiorMapping_tex_v007.osl), the behavior is inconsistent with V-ray and others. Compare cycles_osl.png and vray_osl.png. These are from the attached .blend file; V-ray is offered as a reference.

Exact steps for others to reproduce the error
Files are included in the archive. Maintain the hierarchy - the textures folder needs to exist for the OSL shader to find the file it needs there.

Load attached interior_vray.blend file. This contains Cycles and V-ray shader networks. We'll focus on the Cycles network, but V-ray is there in case it is useful. We'll refer to V-ray render images for comparison.
Press F12 to render a frame with Cycles. You will get something like cycles_osl.png
Compare to the V-ray reference image for the exact same OSL and camera setup (vray_osl.png). The negative-direction facing walls seem to give trouble for the shader in Cycles, but V-ray works fine to create these virtual rooms.

Let's check the positive direction faces :

Switch the active camera to Camera.001 (or load interior_vray2.blend).
Render with F12. Compare the Cycles render with vray_osl_camera001.png. The rooms are created, but the interiors are all mangled compared to the V-ray reference.
Load interior_vray3.blend. This uses a revised OSL (interiorMapping_tex_v007_phil.osl) where the values from (point p_PLocal = transform("object", P);) are negated. Render using Cycles with F12. This looks much closer, but the ceiling and floor images are swapped over (cycles_osl_phil_camera001.png). The negative directions faces are still not rendered correctly with this shader (cycles_osl_phil.png)

interior.zip.

In principle, OSL should be portable and this looks like a bug in the OSL code in blender. It feels like these differences are coming from a single cause, so I put them as a single ticket. If you prefer, I can break them out.

**System Information** Win 10 Pro, 6 GB GTX 1060 **Blender Version** Broken: 2.79b and master Worked: (optional) **Short description of error** For the attached OSL script (interiorMapping_tex_v007.osl), the behavior is inconsistent with V-ray and others. Compare cycles_osl.png and vray_osl.png. These are from the attached .blend file; V-ray is offered as a reference. **Exact steps for others to reproduce the error** Files are included in the archive. Maintain the hierarchy - the textures folder needs to exist for the OSL shader to find the file it needs there. 1) Load attached interior_vray.blend file. This contains Cycles and V-ray shader networks. We'll focus on the Cycles network, but V-ray is there in case it is useful. We'll refer to V-ray render images for comparison. 2) Press F12 to render a frame with Cycles. You will get something like cycles_osl.png 3) Compare to the V-ray reference image for the exact same OSL and camera setup (vray_osl.png). The negative-direction facing walls seem to give trouble for the shader in Cycles, but V-ray works fine to create these virtual rooms. Let's check the positive direction faces : 4) Switch the active camera to Camera.001 (or load interior_vray2.blend). 5) Render with F12. Compare the Cycles render with vray_osl_camera001.png. The rooms are created, but the interiors are all mangled compared to the V-ray reference. 4) Load interior_vray3.blend. This uses a revised OSL (interiorMapping_tex_v007_phil.osl) where the values from (point p_PLocal = transform("object", P);) are negated. Render using Cycles with F12. This looks much closer, but the ceiling and floor images are swapped over (cycles_osl_phil_camera001.png). The negative directions faces are still not rendered correctly with this shader (cycles_osl_phil.png) [interior.zip](https://archive.blender.org/developer/F4699420/interior.zip). In principle, OSL should be portable and this looks like a bug in the OSL code in blender. It feels like these differences are coming from a single cause, so I put them as a single ticket. If you prefer, I can break them out.

Phil Stopford commented

2018-09-14 17:30:40 +02:00

Added subscriber: @phil.stopford

Brecht Van Lommel commented

2018-09-14 18:02:39 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2018-09-14 18:02:39 +02:00

I don't really have the time to debug a complex shader like this, and it's not obvious that the bug is in Cycles. You really need to narrow it down more.

It seems this was adapted from a Blender shader originally, and there's this comment which might be relevant to things being flipped:

- Changed -I into I, as the rooms were inverted, front corner was back.

I don't really have the time to debug a complex shader like this, and it's not obvious that the bug is in Cycles. You really need to narrow it down more. It seems this was adapted from a Blender shader originally, and there's this comment which might be relevant to things being flipped: ``` - Changed -I into I, as the rooms were inverted, front corner was back. ```

Phil Stopford commented

2018-09-14 18:34:36 +02:00

OK. So here's a simpler example, which demonstrates the same problem. The only difference is, again, the negation of the values from the transform("object", P) call. This fixes the texture projection (for the most part). I think this is as simple as it can get.

simpler_interior.zip

OK. So here's a simpler example, which demonstrates the same problem. The only difference is, again, the negation of the values from the transform("object", P) call. This fixes the texture projection (for the most part). I think this is as simple as it can get. [simpler_interior.zip](https://archive.blender.org/developer/F4699911/simpler_interior.zip)

Germano Cavalcante commented

2020-02-05 19:34:31 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-02-05 19:34:31 +01:00

Changed status from 'Confirmed' to: 'Archived'

Germano Cavalcante closed this issue

2020-02-05 19:34:31 +01:00

Germano Cavalcante self-assigned this 2020-02-05 19:34:31 +01:00

Germano Cavalcante commented

2020-02-05 19:34:31 +01:00

Thanks for the report. Unfortunately the scenario described is too time consuming for us to track down, we require the bug reporter to narrow down the problem.
If you are sure that this is a problem in blender, please open a new report clearly identifying the problem.

Thanks for the report. Unfortunately the scenario described is too time consuming for us to track down, we require the bug reporter to narrow down the problem. If you are sure that this is a problem in blender, please open a new report clearly identifying the problem.

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OSL bug? (interior shader) #56804