[Bug?] Why does _ExtractAnalysisMesh change Draft Angle vertex colors?

Rhino Rhino for Windows
1

Hello,

I’m not sure whether this is a bug or I’m missing something.

I need to generate a mesh with Draft Angle Analysis vertex colors applied. I’m using the _ExtractAnalysisMesh command, but as shown, the result (left sphere) differs from the original surface (right sphere) with _DraftAngleAnalysis enabled.

Rhino Version 8 SR32 (8.32.26160.13001, 2026-06-09)

This is the sample file I’m working on: DraftAngleAnalysis.3dm (639.6 KB)

image
image1591×845 87.6 KB

Thanks for the support!

2

bump

3

Can you share the exact steps you followed to get to the situation in the file.

Note that if you change CPlane or viewport that has a different CPlane and draft angle analysis uses the CPlane Z-direction for angle analysis (like in the screenshot) this may change the results from one invocation to the next.

4

Hold on. I’m seeing it too! Here is a ticket for this https://mcneel.myjetbrains.com/youtrack/issue/RH-96404

5

For anyone running into the same issue, my temporary workaround is to use Rhino 7 (7.38.24338.17001, 2024-12-03), since the bug doesn’t seem to be present there.