Modifier - VertexWeightProximity - Resize target object to be smaller - Apply Rotation & Scale #85852

New Issue

Petr Smrtka · 2021-02-21T19:24:02+01:00

Petr Smrtka commented

2021-02-21 19:24:02 +01:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.40

Blender Version
Broken: version: 2.91.2, branch: master, commit date: 2021-01-19 16:15, hash: 5be9ef4177
Worked: (newest version of Blender that worked as expected)

Short description of error
When resizing ( down-scaling ) target objects ( Sphere ) used at VertexWeightProximity, then applying Rotation & Scale, the effected plane resets back based on previous, larger size.

Exact steps for others to reproduce the error

#85852.blend

Very simple scene with one plane, one sphere. The sphere is used as VertexWeightProximity target object to effect the plane vertificies. Plane has 20 by 20 loopcuts, to get more verticies, which are all assigned into Vertex group. This plane has just 2 modifiers in following order : VertexWeightProximity( vertex group = group, target object = sphere, proximity mode = geometry, geometry = vertex, lowest = 1, highest = 0, falloff = smooth, mask vertex group = group ), Displace( using standard built-in cloud texture, coordinates = object, object = sphere, vertext group = group ). When moving the sphere ( target object ), all works fine, the plane verticies are effected by the sphere in proper radius. When scaling the sphere using "S" to be smaller or larger, plane verticies are also effected properly. Now the issue : if the sphere is scaled to be smaller and applying the Rotation & Scale, the effected verticies of the plane are effected in much larger radius than is should be. It seems to me, it's taking the prior sphere size, before applying Rotation & Scale. I got the same issue with Blender 2.93.0 Alpha

regards Petr

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.40 **Blender Version** Broken: version: 2.91.2, branch: master, commit date: 2021-01-19 16:15, hash: `5be9ef4177` Worked: (newest version of Blender that worked as expected) **Short description of error** When resizing ( down-scaling ) target objects ( Sphere ) used at VertexWeightProximity, then applying Rotation & Scale, the effected plane resets back based on previous, larger size. **Exact steps for others to reproduce the error** [#85852.blend](https://archive.blender.org/developer/F9837862/T85852.blend) Very simple scene with one plane, one sphere. The sphere is used as VertexWeightProximity target object to effect the plane vertificies. Plane has 20 by 20 loopcuts, to get more verticies, which are all assigned into Vertex group. This plane has just 2 modifiers in following order : **VertexWeightProximity**( vertex group = group, target object = sphere, proximity mode = geometry, geometry = vertex, lowest = 1, highest = 0, falloff = smooth, mask vertex group = group ), **Displace**( using standard built-in cloud texture, coordinates = object, object = sphere, vertext group = group ). When moving the sphere ( target object ), all works fine, the plane verticies are effected by the sphere in proper radius. When scaling the sphere using "S" to be smaller or larger, plane verticies are also effected properly. Now the issue : if the sphere is scaled to be smaller and applying the Rotation & Scale, the effected verticies of the plane are effected in much larger radius than is should be. It seems to me, it's taking the prior sphere size, before applying Rotation & Scale. I got the same issue with Blender 2.93.0 Alpha regards Petr

Petr Smrtka commented

2021-02-21 19:24:02 +01:00

Added subscriber: @PetrSmrtka

Philipp Oeser commented

2021-02-25 10:07:21 +01:00

Added subscribers: @mont29, @lichtwerk

Philipp Oeser commented

2021-02-25 10:07:21 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2021-02-25 10:07:21 +01:00

Distance calculation of the VertexWeightProximity modifier happens in target local space.

Codewise, check usages of BLI_SPACE_TRANSFORM_SETUP, BLI_space_transform_apply, ...

This means that when scaling down the sphere (object scaling) to e.g. 0.5, then the effective distance of the VertexWeightProximity modifier is 0.5m [when it is set to 1.0m in the UI].
But this also means that when applying scale, the effective distance will be 1.0m again.

Dont think this can be called a bug.
Sure, depending on the usecase, you might want the distance calculation to happen in world space, but this is more of a design decision (or maybe a feature request), but not a bug necessarily.

This is also a nice example of the Geometry Nodes project bringing more flexibility.
You can do this in worldspace there:
T85852_geonodes.blend

So unless @mont29 has objections, I think this can be closed.

Note that for requests and feedback, please use other channels: https://wiki.blender.org/wiki/Communication/Contact#User_Feedback_and_Requests
For more information on why this isn't considered a bug, visit: https://wiki.blender.org/wiki/Reference/Not_a_bug

Distance calculation of the `VertexWeightProximity` modifier happens in target local space. Codewise, check usages of `BLI_SPACE_TRANSFORM_SETUP`, `BLI_space_transform_apply`, ... This means that when scaling down the sphere (object scaling) to e.g. 0.5, then the effective distance of the `VertexWeightProximity` modifier is 0.5m [when it is set to 1.0m in the UI]. But this also means that when applying scale, the effective distance will be 1.0m again. Dont think this can be called a bug. Sure, depending on the usecase, you might want the distance calculation to happen in world space, but this is more of a design decision (or maybe a feature request), but not a bug necessarily. This is also a nice example of the Geometry Nodes project bringing more flexibility. You can do this in worldspace there: [T85852_geonodes.blend](https://archive.blender.org/developer/F9837858/T85852_geonodes.blend) So unless @mont29 has objections, I think this can be closed. Note that for requests and feedback, please use other channels: https://wiki.blender.org/wiki/Communication/Contact#User_Feedback_and_Requests For more information on why this isn't considered a bug, visit: https://wiki.blender.org/wiki/Reference/Not_a_bug

Bastien Montagne commented

2021-02-25 11:26:42 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Archived'

Bastien Montagne closed this issue

2021-02-25 11:26:42 +01:00

Bastien Montagne commented

2021-02-25 11:26:42 +01:00

This is indeed expected behavior currently.

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Modifier - VertexWeightProximity - Resize target object to be smaller - Apply Rotation & Scale #85852