Incorrect mesh deformation behavior when using deform bones from multiple armatures #44081

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pjmendes · 2015-03-21T23:32:20+01:00

pjmendes commented

2015-03-21 23:32:20 +01:00

System Information
Windows 7 64bit, AMD Radeon 5770

Blender Version
Broken: 2.74 rc2 1f547c1
Worked: never

For a mesh using multiple armatures (at least two) with bones that deform it, and weight painted to bones in both armatures, when the bones are animated the deformation behaves incorrectly/unexpectedly.

Additionally, during the weight paint process, the vertices don't interpolate between the bones being painted (as one paints using intermediate values for the weights, such as 0.5 for each bone) as it does with bones in a single armature, it either maps 100% to the first or second bone.

(The vertex groups/weights are correctly created by blender when weight painting, and user care was taken to not have bone name collision, meaning there are no bones with the same name between armatures).

Exact steps for others to reproduce the error
multiple_armatures_weight_bug.blend
In attached file, two armatures were added as modifiers of the Cube mesh. Each armature has a single bone. "Armature" has the left bone ("Bone"), "Armature.001" has the right bone ("Bone2").

"Bone" is 100% weighted to the leftmost vertices of the cube, 50% weighted to the vertices on the middle, and 0% to verts on the right.

"Bone2" is 50% weighted to the middle vertices and 100% to the right.

Moving "Bone", I expected the Cube's left vertices to move 100% with it and the middle ones to move 50%, but it moves all the vertices by 100%, ignoring the 50% weight to the second armature.

Moving "Bone2", this behavior is similar, the weight interpolation is ignored.

Also, during weight painting, as mentioned above, the vertices don't correctly update their visual coordinate between bones to indicate the weight interpolation between them (by this, I mean that, if weight painting in pose mode, and posing the bones, a vertex 50% weighted to each bone should "jump" to in between them, and this does not happen. The vertices will "jump" but only when the weight reaches 0 or 100% for a bone).

**System Information** Windows 7 64bit, AMD Radeon 5770 **Blender Version** Broken: 2.74 rc2 1f547c1 Worked: never For a mesh using multiple armatures (at least two) with bones that deform it, and weight painted to bones in both armatures, when the bones are animated the deformation behaves incorrectly/unexpectedly. Additionally, during the weight paint process, the vertices don't interpolate between the bones being painted (as one paints using intermediate values for the weights, such as 0.5 for each bone) as it does with bones in a single armature, it either maps 100% to the first or second bone. (The vertex groups/weights are correctly created by blender when weight painting, and user care was taken to not have bone name collision, meaning there are no bones with the same name between armatures). **Exact steps for others to reproduce the error** [multiple_armatures_weight_bug.blend](https://archive.blender.org/developer/F153863/multiple_armatures_weight_bug.blend) In attached file, two armatures were added as modifiers of the Cube mesh. Each armature has a single bone. "Armature" has the left bone ("Bone"), "Armature.001" has the right bone ("Bone2"). "Bone" is 100% weighted to the leftmost vertices of the cube, 50% weighted to the vertices on the middle, and 0% to verts on the right. "Bone2" is 50% weighted to the middle vertices and 100% to the right. Moving "Bone", I expected the Cube's left vertices to move 100% with it and the middle ones to move 50%, but it moves all the vertices by 100%, ignoring the 50% weight to the second armature. Moving "Bone2", this behavior is similar, the weight interpolation is ignored. Also, during weight painting, as mentioned above, the vertices don't correctly update their visual coordinate between bones to indicate the weight interpolation between them (by this, I mean that, if weight painting in pose mode, and posing the bones, a vertex 50% weighted to each bone should "jump" to in between them, and this does not happen. The vertices will "jump" but only when the weight reaches 0 or 100% for a bone).

pjmendes commented

2015-03-21 23:32:20 +01:00

Changed status to: 'Open'

pjmendes commented

2015-03-21 23:32:20 +01:00

Added subscriber: @pjmendes

Campbell Barton commented

2015-03-23 14:27:55 +01:00

Changed status from 'Open' to: 'Archived'

Campbell Barton closed this issue

2015-03-23 14:27:55 +01:00

Campbell Barton self-assigned this 2015-03-23 14:27:55 +01:00

Campbell Barton commented

2015-03-23 14:27:55 +01:00

Afraid this is working as intended, for each vertex the weights are normalized and distributed between bones - for that modifier only. Rather then being shared across multiple armatures.

While there are cases where you might want to use multiple armature modifiers, limitations like this make it less useful (YMMV).

closing.

Afraid this is working as intended, for each vertex the weights are normalized and distributed between bones - for that modifier only. Rather then being shared across multiple armatures. While there are cases where you might want to use multiple armature modifiers, limitations like this make it less useful (YMMV). closing.

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Incorrect mesh deformation behavior when using deform bones from multiple armatures #44081