I want to make trusses for the roof but idk why the surface is not in oval shape. I have attached the files and screenshots below, please can anybody help
unnamed.gh (27.4 KB)
Untitled.3dm (308.7 KB)
unnamed.gh and Untitled.3dm tells me you don’t care? The Rhino file appears to be empty and unused by the GH file, which tells me you don’t understand your own code. You joined this forum two hours ago so this is your first post. However, you did post a working GH file. That’s cool.
Divide Domain² and Isotrim use the untrimmed surface, ignoring the ellipse shape, so that’s “why the surface is not in oval shape”.
Next question, of course, is what can you do about it?
You can cull the Isotrim surface fragments (purple group) but that messes up your assumptions about creating trusses, eh? Your distance values are HUGE (millimeter units?) so rounding is more complicated.
unnamed_2024Aug11aa.gh (32.1 KB)
Other options. The white group in this version joins the Isotrim surface fragments and then splits the resulting brep, keeping the inside faces you want on the roof. The purple group culls those faces by area, passing only the larger ones to your code above that creates the trusses.
Clearly, the trusses need work. One option I tried was the red group that looks for lines within the extrusion to be piped. It is incredibly SLOW, I gave up waiting for it to finish.
unnamed_2024Aug11b.gh (39.6 KB)
Yellow groups show another way to cull truss segments, though they still need to be fixed?
unnamed_2024Aug11c.gh (39.4 KB)
P.S. Yet another way to cull truss segments - I’m getting confused so will stop now. 
unnamed_2024Aug11d.gh (36.6 KB)
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Thanks a lot. I am new to rhino and grasshopper, i took part of this code from various youtube videos. it would be of great help if you can suggest some good videos or other ways to learn grasshopper as a beginner.