Regression: Gradient colors in a Grease Pencil material change depending on the visibility of other objects #98882

New Issue

ALEKSANDR_Romanets · 2022-06-14T12:57:21+02:00

2022-06-14 12:57:21 +02:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: GeForce GTX TITAN/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 3.2.0, branch: master, commit date: 2022-06-08 10:22, hash: e05e1e3691
Worked: version: 3.1.2

Short description of error
If I import a Grease pencil object that has a gradient radial fill into the scene, that fill won’t work. But if I turn off the visibility of another Grease pencil object, the visibility of the fill starts working. This behavior is the same for other imported Grease pencil objects. If there are several Grease pencil objects with a radial gradient in the scene, only one will work, the others must be disabled.
I asked other users to test this problem. They confirmed the problem.
Thank you! gradient_problem.mp4

Exact steps for others to reproduce the error

Open attached .blend file
Unhide the "Stroke" Object

problem_gradient.blend I am waiting for your help.

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: GeForce GTX TITAN/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71 **Blender Version** Broken: version: 3.2.0, branch: master, commit date: 2022-06-08 10:22, hash: `e05e1e3691` Worked: version: 3.1.2 **Short description of error** If I import a Grease pencil object that has a gradient radial fill into the scene, that fill won’t work. But if I turn off the visibility of another Grease pencil object, the visibility of the fill starts working. This behavior is the same for other imported Grease pencil objects. If there are several Grease pencil objects with a radial gradient in the scene, only one will work, the others must be disabled. I asked other users to test this problem. They confirmed the problem. Thank you! [gradient_problem.mp4](https://archive.blender.org/developer/F13161970/gradient_problem.mp4) **Exact steps for others to reproduce the error** - Open attached .blend file - Unhide the "Stroke" Object [problem_gradient.blend](https://archive.blender.org/developer/F13161975/problem_gradient.blend) I am waiting for your help.

ALEKSANDR_Romanets commented

2022-06-14 12:57:21 +02:00

Added subscriber: @Alex_Rom

Germano Cavalcante changed title from ~~Problem gradient radial~~ to Regression: Gradient colors in a Grease Pencil material change depending on the visibility of other objects

2022-06-17 15:36:18 +02:00

Germano Cavalcante commented

2022-06-17 15:36:18 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2022-06-17 15:37:22 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2022-06-17 15:37:22 +02:00

Thanks for the report, I can confirm.
I'll look for the commit that introduced the problem.

Thanks for the report, I can confirm. I'll look for the commit that introduced the problem.

Antonio Vazquez commented

2022-06-28 15:50:08 +02:00

Added subscriber: @antoniov

Antonio Vazquez commented

2022-06-28 15:50:08 +02:00

@mano-wii I don't know the draw code for this area and I cannot fix this bug. Could you handle it?

Germano Cavalcante commented

2022-06-28 16:58:47 +02:00

Added subscriber: @fclem

Germano Cavalcante commented

2022-06-28 16:58:48 +02:00

Doing some tests with RenderDoc I noticed that the value of matid is wrong in:
{https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/gpencil/shaders/gpencil_frag.glsl$71}

Moving back a bit the wrong value appears to be added in:
{https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl$128}

Comparing with the way to access a material in {https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl$34}, I tried the solution below and it seems to solve the problem:

diff --git a/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl b/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl
index af8aec85598..5f5419bac47 100644
--- a/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl
+++ b/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl
@@ -125,7 +125,7 @@ void main()
     gpencil_color_output(fill_col, fcol_decode, 1.0, gp_mat._fill_texture_mix);
 
     gp_interp.mat_flag = gp_flag & GP_FILL_FLAGS;
-    gp_interp.mat_flag |= uint(ma1.x) << GPENCIl_MATID_SHIFT;
+    gp_interp.mat_flag |= uint(ma1.x + gpMaterialOffset) << GPENCIl_MATID_SHIFT;
 
     gp_interp.uv = mat2(gp_mat.fill_uv_rot_scale.xy, gp_mat.fill_uv_rot_scale.zw) * uv1.xy +
                    gp_mat._fill_uv_offset;

If I have to guess, I'd say the problem was introduced in eccb0b222e.
I'm not sure if that is the ideal solution, @fclem any thoughts?

Doing some tests with `RenderDoc` I noticed that the value of `matid` is wrong in: {https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/gpencil/shaders/gpencil_frag.glsl$71} Moving back a bit the wrong value appears to be added in: {https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl$128} Comparing with the way to access a material in {https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl$34}, I tried the solution below and it seems to solve the problem: ``` diff --git a/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl b/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl index af8aec85598..5f5419bac47 100644 --- a/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl +++ b/source/blender/draw/engines/gpencil/shaders/gpencil_vert.glsl @@ -125,7 +125,7 @@ void main() gpencil_color_output(fill_col, fcol_decode, 1.0, gp_mat._fill_texture_mix); gp_interp.mat_flag = gp_flag & GP_FILL_FLAGS; - gp_interp.mat_flag |= uint(ma1.x) << GPENCIl_MATID_SHIFT; + gp_interp.mat_flag |= uint(ma1.x + gpMaterialOffset) << GPENCIl_MATID_SHIFT; gp_interp.uv = mat2(gp_mat.fill_uv_rot_scale.xy, gp_mat.fill_uv_rot_scale.zw) * uv1.xy + gp_mat._fill_uv_offset; ``` If I have to guess, I'd say the problem was introduced in eccb0b222e. I'm not sure if that is the ideal solution, @fclem any thoughts?

Clément Foucault commented

2022-06-28 17:44:44 +02:00

@mano-wii It is the right fix. You can commit it.