Sporph mapping issue on one face of a compound surface

Grasshopper Pufferfish
1

Hi everyone,

I’m currently developing a Grasshopper workflow that involves:

  1. Flattening a compound surface (UnrollPolySurface)
  2. Overlaying geometry onto the flattened result
  3. Mapping the relevant sections back onto the original 3D form using Sporph.

The issue I’m running into I’m thinking stems from the UV mapping of the original and unrolled surfaces.

I’ve attached an image showing the UV direction arrows on both the original compound surface and the unrolled result.

image
image616×705 114 KB

What I’m observing is:

  • The two flat faces (cyan and green) maintain consistent UV directions after unrolling.
  • The curved central face (yellow) has its UV directions reversed in both axes.
  • The arrows appear visually “flipped” relative to the original surface.

This leads to the following behaviour:

  • When I overlay a circular mesh on the flattened layout and map it back using Sporph, the regions corresponding to cyan and green faces map correctly.
  • The region corresponding to the yellow curved face is rotated 180deg.
  • If I isolate and map only the yellow surface independently, the issue doesn’t occur.

I tried using the SwapSrfDir component to switch the UV values but it just ended up mangling the 3D surfaces.

How can I correct this UV direction mismatch so Sporph maps the yellow curved face without the 180deg rotation? Is it even fixable or is this expected behaviour? Thanks in advance for any help or advice you can offer!

compound surface mapping.gh (29.8 KB)