Grease Pencil: Texture Brush Alpha Issue #113023

New Issue

James-Pendleton · 2023-09-28T17:16:02+02:00

James-Pendleton commented

2023-09-28 17:16:02 +02:00

System Information
Operating system: Windows 10.0.19045 Build 19045
Graphics card: NVIDIA GeForce RTX 3070

Blender Version
Broken: 3.6.4, 21bfc5e7fe, master, 2023-09-25
Worked: (newest version of Blender that worked as expected)

Short description of error
An issue occurs where the transparency of an image texture brush in Grease Pencil breaks, and shows a border matching the world color.

This happens when the stroke is beneath another grease pencil stroke/fill in the layer hierarchy, but in front of it in 3D space.

In the attached example, we have the world color set to a light red. On one layer, a white circle, and on another layer, the brush strokes.

The brush strokes are in front of the white circle in 3D space. When the layer ordering has the stroke at the top, no issues (See Image 1)

But if we swap the order of the layers, the transparency of the stroke breaks, revealing an unsightly border matching the world color (See Image 2)

This seems like a huge issue with Grease Pencil that has persisted for years at this point. One of Blender's main draws is that you can order objects in 3D space and not have to concern yourself with layer ordering, and yet this bug completely negates that.

Exact steps for others to reproduce the error
.blend file included below

**System Information** Operating system: Windows 10.0.19045 Build 19045 Graphics card: NVIDIA GeForce RTX 3070 **Blender Version** Broken: 3.6.4, 21bfc5e7fe3f, master, 2023-09-25 Worked: (newest version of Blender that worked as expected) **Short description of error** An issue occurs where the transparency of an image texture brush in Grease Pencil breaks, and shows a border matching the world color. This happens when the stroke is beneath another grease pencil stroke/fill in the layer hierarchy, but in front of it in 3D space. In the attached example, we have the world color set to a light red. On one layer, a white circle, and on another layer, the brush strokes. The brush strokes are in front of the white circle in 3D space. When the layer ordering has the stroke at the top, no issues (See Image 1) But if we swap the order of the layers, the transparency of the stroke breaks, revealing an unsightly border matching the world color (See Image 2) This seems like a huge issue with Grease Pencil that has persisted for years at this point. One of Blender's main draws is that you can order objects in 3D space and not have to concern yourself with layer ordering, and yet this bug completely negates that. **Exact steps for others to reproduce the error** .blend file included below

Texture Brush Alpha Issue.blend

5.7 MiB

Image 1.png

524 KiB

Image 2.png

654 KiB

James-Pendleton added the

labels 2023-09-28 17:16:02 +02:00

Germano Cavalcante commented

2023-09-28 23:44:28 +02:00

I can confirm. But it is quite possible that this is a limitation and that the order of the layers is drawn from bottom to top and occlusion is tested considering only the depth and not the transparency.

If so, it may not be solvable.

It seems related to these other issues:
#78795: GPencil: Texture Image Alpha pass through grease pencil strokes
#105227: Grease Pencil Blur makes a tight white line beteween to diferent GP Objects.

I can confirm. But it is quite possible that this is a limitation and that the order of the layers is drawn from bottom to top and occlusion is tested considering only the depth and not the transparency. If so, it may not be solvable. It seems related to these other issues: #78795: GPencil: Texture Image Alpha pass through grease pencil strokes #105227: Grease Pencil Blur makes a tight white line beteween to diferent GP Objects.

Germano Cavalcante added

and removed

labels 2023-09-28 23:44:42 +02:00

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