grasshopper eats isocurves v0.gh (90.0 KB)
I am using the latest R8 RC on windows 11.
[Bug?] Trimmed surface’s Isocurves missing at the seam position - Grasshopper - McNeel Forum
I am trying to understand the issue. To see what is happening I attached a list item component.
Now I see that the last and first isocurve are on the same place.
I see that the four points you made are nicely along the Y- axis.
The Iso Curve projects them around the curved surface. Because the surface is completely closed, the end of surface and beginning of surface are on the same place. Making the first and last isocurve on the same place.
Both are there, but you cannot see them unless seperated by list item component.
Maybe I do not understand enough about isocurves, but there is no isocurve lost, just doubled.
Regards, Eef
I am macbook latest version
Version 8 (8.18.25084.13002, 2025-03-25)
unnamed (27.3.2025, 15.46.41).gh (23.3 KB)
Shouldn’t the Iso Curve component show something in this case?
@DanielPiker, please help me see what the cause is. I remember it was not like this in R7.
@Gijs Please help me look into this, see if this is a bug.
acts the same in Rhino 7. You need a uv point on the surface, try with the surface closest point first to get the uv point. Then this gives this in both Rhino 7 and 8:
grasshopper eats isocurves v0.gh (93.1 KB)
If it shows no isocurves at all, I will assume I have found the wrong component. However, the Iso Curve component shows all but two at the ends. That makes me think it was designed to display the correct isocurves but lost part of that ability after a rogue update.
Can it reliably display all but the two at the ends? If so, I would like to create a component that trims those two (retrieved from the underlying untrimmed surface) and adds them back to the rest for computational efficiency. Hi, @DavidRutten, was it designed to display all the isocurves on a trimmed surface?
Help!
it never happend to me to be in need of that, but I also think the component is not displaying/outputting curves if those curves are seams, and I guess it should
Yes, it also has problem at the seam position. I can get Isocurves with Surface | Curve intersection, but that is too costly.
Hi @Quan_Li,
This is fixed on next 8.20 RC.
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Finally…let me cry for a moment… 
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