[BUG] - Rhino 8 - Model Object Ignores Surface Trims


Came a cross a set of new bugs in the latest WIP, steps to reproduce:

-Create a new boundary surface in Grasshopper from curves
-Connect the Surface result into a custom preview component
(results in incorrectly flipped normals that you can not correct with the flip node or any other
method (that I could find))

-Connect the Surface result into a Model Object node
(results in the overall surface bounds being returned instead of the trimmed/shaped surface)

Please see the screenshots and attached gh file for your reference:

Custom Preview:

Boundary Surfaces → Model Object → Custom Preview:

Rhino PlanarSrf Referenced Surface → Custom Preview:

Rhino PlanarSrf Referenced Surface → Model Object → Custom Preview:

Graph Space:

@John_Brock @brian @BrianJ @wim @AndyPayne

Thank you all!

20230714_Boundary_Surface_Model_Object_Boundary_Bug_01a.gh (24.9 KB)

Hi @michaelvollrath,

I have not looked at your file. But in the case of creating surfaces from planar closed curves, the direction of the curves matter. If you want your planar curves to create surfaces whose normal is in the world z-axis direction, make sure the curve’s direction is counter-clockwise to the world xy-plane.

– Dale

Thanks @dale, I did check the curves with the Dir command and all of them were oriented consistently yet the boundary surface component yielded half Z positive and half Z negative regardless.

Oddly, after a computer restart the Boundary Surface component seems to be working fine again despite not changing anything in the script or model.

The Model Object component, however, is still returning the full rectangular bounding surface instead of the expected surface bounded by the referenced curves.

Thanks for the response!


Two are oriented clockwise and the others counter-clockwise.

test_michael.gh (6.2 KB)

– Dale

:pensive: my apologies on that, I could have sworn I saw them all as clockwise.

Did the Model Objects return correct bounds on your end?

Kindly bumping this one again @kike @AndyPayne :crossed_fingers:t4:

Still having this bug in the BETA release.

To repeat:

-create a surface in grasshopper, trim said surface with any number of splitting/cutting operations.

-feed the trimmed surfaces into a model object component to prep for baking

-note the surface is untrimmed and when baked, will bake the full, untrimmed surface(s)

Custom Preview/Expected Results:

GH Preview of Model Object & Bake Result:

The model object preview is also the bake result.

Graph Space:

The baked surfaces will have their respective materials applied but completely ignore the trim data, thus overlapping the full untrimmed surface for each trimmed sub surface.

This example results in 7 overlapping untrimmed surfaces.

Another user posted the same issue here:

Thank you all for your help!

Hi @michaelvollrath,

This should be fixed on todays build.


Wonderful, I look forward to it. Thank you @kike !