BUG - Extrude - Negative Value Creates Invalid Brep


I found a bug in 8.8.24142.13001 with the Extrude component.

If given a negative value, the extrude component creates an invalid Brep, if given a positive value it is fine.

I get that I’m “extruding the opposite of the face normal” with a negative value but the resulting brep should be a new solid brep with outward facing normals correct? That’s how it’s always worked to my knowledge and to go in now and need to add surface normal checking/flipping for each instance like this seems like a bug so I’m reporting it here as such.

Downstream, the invalid Brep will also not Push in a Content Cache.

Graph Space:

Please see .gh file attached to reproduce,

Thank you!

20250527_Negative_Values_In_Extrude_Create_Invalid_Brep_01a.gh (8.6 KB)

Just for reference, this is what I see in 8.7.24113.23001 (I guess it´s the latest SRC 8.7.X).

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Kindly bumping this to the top again… Hoping this can be fixed in the next SR maybe?

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To me this seems like the problem is in the Merge Faces component.

I recently started seing a problem which could be related. I’m using this script to create offset breps and it also uses the Merge Faces component.

brep_offset_c.gh (167.7 KB)


That’s correct.

RH-82374 Grasshopper: MergeFaces causes Invalid Brep


Ahh thank you @martinsiegrist , you’re correct!

@wim thanks for the youtrack !

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RH-82374 is fixed in Rhino 8 Service Release 8.

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Awesome, thank you!

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