Squish in GH Python uses wrong surface despite correct input after split

[poojan_venkatesh]

squish using python.gh (32.5 KB)
Hi all,

I’m working on an automated flattening process using _Squish inside a Grasshopper Python component in Rhino 7.

Here’s what I’m trying to do:

1. Split a surface in Grasshopper (e.g., using brep).
2. Send the trimmed surfaces into a GH Python component.
3. Bake the surface.
4. Use _Squish on the baked geometry and retrieve the result back into GH.

Problem

Even though the split works correctly and I pass the trimmed surfaces to Python, the _Squish command always processes the original (pre-split) surface — not the trimmed result.

What I tried

• I confirmed that the srfs input into Python shows only the trimmed surfaces.
• I bake the surface, then try to select and squish it using its Id.
• I tried using both:
  • Grouping baked geometry and selecting it
  • Baking with attributes (Name) and using _SelName
• But Squish seems to still act on the wrong geometry.

How can I ensure that the Squish command only acts on the baked version of the currently selected trimmed surface?

Is there a more reliable way to bake, fetch, and squish the geometry—perhaps using Squisher() directly in RhinoCommon?

Any help or sample patterns would be much appreciated

Thanks!

[Eef_Weenink]

Maybe this is helpfull?

Using Rhino's squish command in Grasshopper

Thank you! This was exactly what I was trying to do. I ended up figuring out how to use this to un-squish curves as well. [image] Squished.gh (16.1 KB)

[TomTom (Tom)]

Trimmed surfaces are “Breps” and not “Surfaces” in Rhino and Grasshopper.
Since Grasshopper itself is quite liberal with input, performing implicit type conversions for you, you likely feed in a Brep (=Trimmed surface) to a Surface (=Raw surface) input.

public Brep SquishSurface(
  SquishParameters sp,
  Surface surface,
  IEnumerable<GeometryBase> marks,
  List<GeometryBase> squished_marks_out
)

The Squisher class only supports Surface (=untrimmed) input.

You can however try to reapply the trim on your squished surface.
See Copy Trim component

[pierrec (Pierre Cuvilliers)]

I think this is what you want:

DI-207248_squish using python_PEC.gh (21.0 KB)

The trick is to make sure you are setting your input type to Brep in GH, calling the Squisher.SquishSurface() method like this:

squisher = rg.Squisher()
marks = list(edge_crvs) + dots
squished_marks = [_ for _ in marks]
squished_marks = System.Collections.Generic.List[rg.GeometryBase]()
squished_brep = squisher.SquishSurface(
    rg.SquishParameters(),
    brep.Faces[0],
    marks,
    squished_marks
)

Note that this method can accept Rhino.Geometry.Surface as its second parameter, which is a generic type for trimmed and untrimmed surfaces, including a single BrepFace.

I didn’t look very carefully at the rest of the script after that.

[pierrec (Pierre Cuvilliers)]

@TomTom

The Squisher class only supports Surface (=untrimmed) input.

It only supports Rhino.Geometry.Surface, which is (almost?) the same as GH’s Surface parameter type, but different to GH’s Surface input type in Python script components. (Yes, I know, confusing)

Rhino.Geometry.Surface is a parent class for BrepFace, so it can support trimmed surfaces. The full inheritance chain: Rhino.Runtime.CommonObject→Rhino.Geometry.GeometryBase→Rhino.Geometry.Surface→Rhino.Geometry.SurfaceProxy→BrepFace

For reasons that I’ve forgotten, selecting Surface as a type hint in a GH Python Script component will convert almost everything to a Rhino.Geometry.NurbsSurface, which does not support trims (and is a subclass of Rhino.Geometry.Surface).

[poojan_venkatesh]

Thank you so much!