UV of non-planar triangular surface

Hi! I am trying to change the UV of a non-planar triangle. Not just switch them but move from which corners of the triangle they go from, to then be able to create a mesh the way I want it.

This is the current UV and the way I want it to be. I know the standard UV is made from the shortest paths, but the surface will be turned into a gridshell mesh and I need the mesh edges to meet at the top corner, not one of the bottom ones.

Any ideas on how I can solve this?


Hi Ida - not easily I would say - one trick is to loft the two sides you want and then make a patch surface from points or curves taken from the original and use the new surface as a starting surface for the patch - I’ll see if I can cook up an example that works.

That trick does not like the singularity, so far.


@idarobler How close to the current shape does the new surface need to be?

If only the edges need to match then you can use EdgeSrf to create a new surface:
DupEdge the edges of the current surface.
EdgeSrf and select the bottom curve first, then the other two curves. EdgeSrf will create a surface isocurves which converge at the apex formed by the second and third curves selected.

If the new surface needs to be close in shape to the original surface:
Create a new surface with desired UV arrangement using the steps above. This surface will be used as the starting surface in Patch.
Mesh the original surface. This creates a mesh which will be used to match the new surface to.
Patch, click on Select Starting Surface and select the new surface as the starting surface. Click on Preserve Edges and complete the Patch command.

Thanks for the reply. The surface is an edge surface created in grasshopper, so recreating it in Rhino should hopefully give the same shape. Didn’t know that the order of the edges mattered, so I will try it out tomorrow :grin:

The shape of 3 sided surfaces made with EdgeSrf depends on the order the curves are selected.

Noticed, the new surface is slightly different, but close enough for what I’m doing. Thank you!