Sub node messes up the dot product calculation. #98942

New Issue

kursad k · 2022-06-16T20:39:57+02:00

kursad k commented

2022-06-16 20:39:57 +02:00

System Information
Operating system: Windows 11

Blender Version
Broken: c135ddb9b4

Short description of error

It looks like adding a subdivision modifier in the mix messes up the dot product calculation. You can see that in the image below once the subd node enabled, all the ranging values change to 1.0 I am not sure if this is an issue with the Edge Vertices node or the Math node itself.

Exact steps for others to reproduce the error

Load the attached

Enable and disable the subd node while paying attention to the spreadsheet.

subdmesh_16062022_1323_18.zip

**System Information** Operating system: Windows 11 **Blender Version** Broken: c135ddb9b4cb **Short description of error** It looks like adding a subdivision modifier in the mix messes up the dot product calculation. You can see that in the image below once the subd node enabled, all the ranging values change to 1.0 I am not sure if this is an issue with the Edge Vertices node or the Math node itself. ![image.png](https://archive.blender.org/developer/F13175358/image.png) **Exact steps for others to reproduce the error** Load the attached Enable and disable the subd node while paying attention to the spreadsheet. [subdmesh_16062022_1323_18.zip](https://archive.blender.org/developer/F13175353/subdmesh_16062022_1323_18.zip)

kursad k commented

2022-06-16 20:39:57 +02:00

Added subscriber: @kursadk

Leon Schittek commented

2022-06-16 21:43:22 +02:00

Added subscriber: @lone_noel

Leon Schittek commented

2022-06-16 21:43:22 +02:00

Changed status from 'Needs Triage' to: 'Archived'

Leon Schittek closed this issue

2022-06-16 21:43:22 +02:00

Leon Schittek commented

2022-06-16 21:43:22 +02:00

Hello, @kursadk and thanks a lot for the report! I think this is the expected behavior, though - see below for the explanation.
I'll close the report, but feel free to get back at me, if you think I misunderstood what you mean.

In the provided setup the dot product is evaluating how "parallel" the two vectors pointing to the positions of neighboring vertices are (with some domain interpolation going on as well).

When subdividing the edges, the neighboring vertices move closer and closer to each other and therefore making their position vectors more parallel. After 6 subdivisions the neighboring vertices are so close to each other that the dot product evaluates very close to 1.

I simplified the mesh to one edge and visualized the points created by the subdivision node to show what I mean:

#98942.mp4

Hello, @kursadk and thanks a lot for the report! I think this is the expected behavior, though - see below for the explanation. I'll close the report, but feel free to get back at me, if you think I misunderstood what you mean. --- In the provided setup the dot product is evaluating how "parallel" the two vectors pointing to the positions of neighboring vertices are (with some domain interpolation going on as well). When subdividing the edges, the neighboring vertices move closer and closer to each other and therefore making their position vectors more parallel. After 6 subdivisions the neighboring vertices are so close to each other that the dot product evaluates very close to 1. I simplified the mesh to one edge and visualized the points created by the subdivision node to show what I mean: [#98942.mp4](https://archive.blender.org/developer/F13175581/T98942.mp4)

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Sub node messes up the dot product calculation. #98942