grease pencil vertex group add fails in python #56280

New Issue

goat head · 2018-08-09T03:50:18+02:00

goat head commented

2018-08-09 03:50:18 +02:00

System Information
Operating system and graphics card
Fedora, Intel Graphics

Blender Version
latest blender2.8 branch from git

Short description of error
the python below should add points to the new vertex group, but it fails.

Exact steps for others to reproduce the error
v = ob.vertex_groups.new(name="mygroup")
v.add( [1,2,3], weight=1.0, type="ADD")

**System Information** Operating system and graphics card Fedora, Intel Graphics **Blender Version** latest blender2.8 branch from git **Short description of error** the python below should add points to the new vertex group, but it fails. **Exact steps for others to reproduce the error** v = ob.vertex_groups.new(name="mygroup") v.add( [1,2,3], weight=1.0, type="ADD")

goat head commented

2018-08-09 03:50:18 +02:00

Added subscriber: @hartsantler

Antonio Vazquez was assigned by Bastien Montagne

2018-08-09 11:04:31 +02:00

Antonio Vazquez commented

2018-08-09 13:59:19 +02:00

Added subscriber: @mont29

Antonio Vazquez commented

2018-08-09 13:59:19 +02:00

I can confirm this, but it's not a bug but an unsupported python API feature.

The weight data in grease pencil reuse some areas of vertex groups used in meshes, but the weight point information is handle totally different due the nature of the internal strokes data and this is the reason the weight add is not working.

I will investigate how we can expose this api in python.

@mont29 what we must do with this bug report? change status, close, I don't know?

I can confirm this, but it's not a bug but an unsupported python API feature. The weight data in grease pencil reuse some areas of vertex groups used in meshes, but the weight point information is handle totally different due the nature of the internal strokes data and this is the reason the weight add is not working. I will investigate how we can expose this api in python. @mont29 what we must do with this bug report? change status, close, I don't know?

Antonio Vazquez commented

2018-08-09 14:04:47 +02:00

@hartsantler You could use a different approach.

After creating the vertex group, you can select the points of the stroke and then use the operator gpencil.vertex_group_assign.

I have not tested but I think it can be work.

@hartsantler You could use a different approach. After creating the vertex group, you can select the points of the stroke and then use the operator gpencil.vertex_group_assign. I have not tested but I think it can be work.

Antonio Vazquez commented

2018-08-09 16:19:52 +02:00

Looking in detail in python API, the add function will never work because when adding a weight to vertex in a mesh, the vertex 1, 2, x is know, but in grease pencil, the vertex 1, 2, n is not like that, first you need define in what layer, in what frame and in what stroke are you adding the weight.

For example, the weight 1.0 to vertex 5 could be: Layer A->Frame 32->Stroke 75->Vertex 5 = 1.0

I need design an API to do that, but in any case, always will need a stroke parameter, never object only.

Looking in detail in python API, the add function will never work because when adding a weight to vertex in a mesh, the vertex 1, 2, x is know, but in grease pencil, the vertex 1, 2, n is not like that, first you need define in what layer, in what frame and in what stroke are you adding the weight. For example, the weight 1.0 to vertex 5 could be: Layer A->Frame 32->Stroke 75->Vertex 5 = 1.0 I need design an API to do that, but in any case, always will need a stroke parameter, never object only.

Antonio Vazquez commented

2018-08-11 17:07:48 +02:00

Changed status from 'Open' to: 'Archived'

Antonio Vazquez closed this issue

2018-08-11 17:07:48 +02:00

Antonio Vazquez commented

2018-08-11 17:07:48 +02:00

We can consider this as a non supported python api, so we can close the bug.

Nicolas Antille commented

2019-05-30 16:25:11 +02:00

Added subscriber: @nantille

Nicolas Antille commented

2019-05-30 16:25:11 +02:00

This comment was removed by @nantille

*This comment was removed by @nantille*

Maurizio Memoli commented

2019-09-29 04:05:15 +02:00

Added subscriber: @maumemoli

Maurizio Memoli commented

2019-09-29 04:05:15 +02:00

In #56280#525614, @antoniov wrote:
@hartsantler You could use a different approach.

After creating the vertex group, you can select the points of the stroke and then use the operator gpencil.vertex_group_assign.

I have not tested but I think it can be work.

Anything that forces the python developers use bpy.ops because of limits in the API shouldn't be an option...
I was wondering if there is any update on this issue.

> In #56280#525614, @antoniov wrote: > @hartsantler You could use a different approach. > > After creating the vertex group, you can select the points of the stroke and then use the operator gpencil.vertex_group_assign. > > I have not tested but I think it can be work. Anything that forces the python developers use bpy.ops because of limits in the API shouldn't be an option... I was wondering if there is any update on this issue.

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grease pencil vertex group add fails in python #56280