GLSL/Matcap shading not working #37259

New Issue

Jesse Martinez · 2013-10-30T06:43:45+01:00

Jesse Martinez commented

2013-10-30 06:43:45 +01:00

%%%--- Operating System, Graphics card ---
Comp: Dell Vostro A860 Laptop
OS: Windows Vista Home Basic SP2 32-bit
CPU: Intel Celeron 560 @ 2.13 GHz
RAM: 3.0 GB
GPU: Intel GMA 965, drivers are as up-to-date as possible

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

Blender 2.69, also happens in 2.68
Worked in 2.67b
All are 32-bit versions

- Short description of error ---

Blender will only render a Black/Green/Orange solid colored geometry (likely for the outline) when using GLSL shading mode or Matcaps. BGE only shows solid colors like white, black, grey, etc. Multi/Singletexture shading works fine.

This happens on all .blend scenes including the start scene.

Console spits out this message as well:
GPUShader: linking error:
Fragment shader uses varying gl_FrontFacing but vertex shader does not write to it.

What does that error mean in plain English?

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

Use an ancient (2008-era) computer w/ Intel GFX maybe?
%%%

%%%--- Operating System, Graphics card --- Comp: Dell Vostro A860 Laptop OS: Windows Vista Home Basic SP2 32-bit CPU: Intel Celeron 560 @ 2.13 GHz RAM: 3.0 GB GPU: Intel GMA 965, drivers are as up-to-date as possible - Blender version with error, and version that worked --- Blender 2.69, also happens in 2.68 Worked in 2.67b All are 32-bit versions - Short description of error --- Blender will only render a Black/Green/Orange solid colored geometry (likely for the outline) when using GLSL shading mode or Matcaps. BGE only shows solid colors like white, black, grey, etc. Multi/Singletexture shading works fine. This happens on all .blend scenes including the start scene. Console spits out this message as well: GPUShader: linking error: Fragment shader uses varying gl_FrontFacing but vertex shader does not write to it. What does that error mean in plain English? - Steps for others to reproduce the error (preferably based on attached .blend file) --- Use an ancient (2008-era) computer w/ Intel GFX maybe? %%%

Jesse Martinez commented

2013-10-30 06:43:45 +01:00

Changed status to: 'Open'

Jesse Martinez commented

2013-10-30 06:47:47 +01:00

%%%See attached image to see issue.%%%

Sergey Sharybin commented

2013-10-30 09:40:49 +01:00

%%%This issue is caused by really poor GLSL support and doesn't have functionality to properly. The changes which made shading not working for you were caused by a bug fix at svn rev57702.

Brecht, perhaps we could try faking gl_FrontFacing for the cards which doesn't support it, or just consider this GPU as not supported for GLSL shading?%%%

%%%This issue is caused by really poor GLSL support and doesn't have functionality to properly. The changes which made shading not working for you were caused by a bug fix at svn rev57702. Brecht, perhaps we could try faking gl_FrontFacing for the cards which doesn't support it, or just consider this GPU as not supported for GLSL shading?%%%

Brecht Van Lommel commented

2013-10-30 15:00:36 +01:00

%%%This is a driver bug, this variable should be supported in any GLSL version, and the error message makes no sense. The GLSL specification says this is a read-only builtin variable, and it would not actually be possible to to determine its value in the vertex shader. The latest driver for this card is from 4 years ago, so that means Intel will not fix this bug.

We will soon make even more changes that require a good OpenGL implementation, so I think we just have to accept this as a graphics card / driver combination that we can no longer fully support. It would be nice to support some sort of OpenGL software rendering fallback at some point, but I would not consider that a bug.%%%

%%%This is a driver bug, this variable should be supported in any GLSL version, and the error message makes no sense. The GLSL specification says this is a read-only builtin variable, and it would not actually be possible to to determine its value in the vertex shader. The latest driver for this card is from 4 years ago, so that means Intel will not fix this bug. We will soon make even more changes that require a good OpenGL implementation, so I think we just have to accept this as a graphics card / driver combination that we can no longer fully support. It would be nice to support some sort of OpenGL software rendering fallback at some point, but I would not consider that a bug.%%%

Brecht Van Lommel commented

2013-10-30 15:00:36 +01:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2013-10-30 15:00:36 +01:00

Jesse Martinez commented

2013-10-30 21:46:25 +01:00

%%%How would I be able to fix this myself within Blender (apart from acquiring a new computer)?%%%

Brecht Van Lommel commented

2013-11-01 21:42:32 +01:00

%%%If you compile your own Blender, you can revert the changes. Basically you go into the folder source/blender/gpu, and replace every mention of "gl_FrontFacing" by "1". This will give incorrect lighting in some cases, but this feature is needed to handle lighting correctly. That or avoid using GLSL mode.

I'm sorry I can't give a simpler answer, but we can't support such older cards well while keeping things working correct and with good performance on newer cards too.

%%%

%%%If you compile your own Blender, you can revert the changes. Basically you go into the folder source/blender/gpu, and replace every mention of "gl_FrontFacing" by "1". This will give incorrect lighting in some cases, but this feature is needed to handle lighting correctly. That or avoid using GLSL mode. I'm sorry I can't give a simpler answer, but we can't support such older cards well while keeping things working correct and with good performance on newer cards too. %%%

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GLSL/Matcap shading not working #37259