Hello, I just started learning grasshopper, and I encountered a problem that probably has an easy solution. How to divide a lofted 3rddegree surface into equal parts? I tried with “divide surface” and “divide domain2” , but the division is based on how far are the points on curves that made the surface in the first place.
Your problem is a consequence of mainly two things:

the origin curves have an “uneven” structure. In other words, the space between the points is not the same along the curves. So, if you create a loft from those curves, the structure of the surface will follow the structure of the curves.

the two curves are not the same or they have a different amount of points. So, the rhino/grasshopper loft command will try to guess how to generate the loft and the result won’t likely be the one you expected.
Another issue is that there is no perfect solution to your problem. This type of surface can’t be divided into equal parts unless it’s deformed/optimized.
One simple improvement to your problem is to use the command REBUILD. This will reset the structure of the curves according to a desired number of points, which will be distributed evenly along the curves. As a result, the structure of your loft will be more even as well as the result of the isotrim command.
The REBUILD CURVE command can be used to adjust your curves first, but you can also use REBUILD internally in the LOFT component as I show in the image.
I hope this helps!
Be aware that Rebuild will usually alter the shape of the curves or surfaces. The difference may or may not be significant depending on what you are doing.
Correct, I should have mentioned that. You should rebuild with enough points so that your original curves don´t change. Above a certain amount, more points won´t help since it will make the resulting surface tiles unnecessarily complex and too heavy.
That’s significantly different than what is desired for “a problem that probably has an easy solution”.