GeometryNodes: CurveToMesh assumes radius=1, read radius assumes radius=0 if non-existing #116577

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D0ppelgaenger · 2023-12-27T11:52:00+01:00

D0ppelgaenger commented

2023-12-27 11:52:00 +01:00

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2060/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 535.98

Blender Version
Broken: version: 4.1.0 Alpha, branch: main, commit date: 2023-12-25 19:48, hash: 140f5f619dcf
Worked: -

Short description of error
If the curve used in a curve to mesh does not have a radius attribute, it assumes a radius of 1m.
If you however try to view/use the radius attribute via the read radius, it assumes a radius of 0m.

I understand that it makes sense from a usability standpoint, that Curve to Mesh assumes a radius of 1. That way, you aren't forced to assign a radius to a curve every time, just to be able to use curve to mesh "correctly".
I also understand that a non-existing attribute by default reads 0.
Yet, I think that it is incorrect for both values to not be the same.
In my usecase I capture the radius attribute before converting it to a mesh and want to use that information later on the mesh.
However, the radius I captured is not the same one, that is actually used in the curve to mesh operation, which makes my calculations incorrect (if radius not implicitly assigned used set curve radius).

Exact steps for others to reproduce the error

Add GeometryNodesModifier to default cube.
Create new NodeTree.
Add a "CurvePrimitve - Arc" (or other primitive).
Add a "Curve to Mesh" with a "CurveCircle" as profile.
Connect the viewer to the Arc and a "Geomety - Read - Radius" and connect and view the attribute on the curve's controlpoints.
The read attribute is 0, however ctm assumes a value of 1.

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2060/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 535.98 **Blender Version** Broken: version: 4.1.0 Alpha, branch: main, commit date: 2023-12-25 19:48, hash: `140f5f619dcf` Worked: - **Short description of error** If the curve used in a curve to mesh does not have a radius attribute, it assumes a radius of 1m. If you however try to view/use the radius attribute via the read radius, it assumes a radius of 0m. I understand that it makes sense from a usability standpoint, that Curve to Mesh assumes a radius of 1. That way, you aren't forced to assign a radius to a curve every time, just to be able to use curve to mesh "correctly". I also understand that a non-existing attribute by default reads 0. Yet, I think that it is incorrect for both values to not be the same. In my usecase I capture the radius attribute before converting it to a mesh and want to use that information later on the mesh. However, the radius I captured is not the same one, that is actually used in the curve to mesh operation, which makes my calculations incorrect (if radius not implicitly assigned used set curve radius). **Exact steps for others to reproduce the error** 1. Add GeometryNodesModifier to default cube. 2. Create new NodeTree. 3. Add a "CurvePrimitve - Arc" (or other primitive). 4. Add a "Curve to Mesh" with a "CurveCircle" as profile. 5. Connect the viewer to the Arc and a "Geomety - Read - Radius" and connect and view the attribute on the curve's controlpoints. 6. The read attribute is 0, however ctm assumes a value of 1.

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D0ppelgaenger added the

labels 2023-12-27 11:52:01 +01:00

D0ppelgaenger changed title from ~~GeometryNodes: CurveToMesh assumes radius=1, read radius assumes radius=0~~ to GeometryNodes: CurveToMesh assumes radius=1, read radius assumes radius=0 if non-existing

2023-12-27 11:54:09 +01:00

Iliya Katushenock added the

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GeometryNodes: CurveToMesh assumes radius=1, read radius assumes radius=0 if non-existing #116577