I have a problem with the lines projected. they are randomly projected.

Great! Thanks for taking the time to problem-solve.

Hi Peeter, I found the problem and it's really silly. Your input curves are "flipped", which in return generates a flipped lofted surface, which generates the projected rectangles. Then, if you get the control points of those rectangles for the lines, those points are ordered "counterclockwise" compared with the original rectangles, which points are ordered "clockwise", resulting in the diagonals. There are a lot of ways to fix this, we could flip the projected rectangles using the flip curve component. We could reverse the lofted surface. But I prefer handling it at the very source, which simply means flipping your input curves in Rhino. Select the 4 input curves and type in "_Flip" in the command prompt in Rhino and this should do the trick. On a side note; Please use the output curves from the rectangular grid to project on top of the surface. Not the moved rectangles. This minimizes the chances of having rectangles that are not fully projected on the surface. Cheers! Arie

Hey Arie, I tried both making the rectangle grid smaller than the surface as well as flattening the curves. I still get the diagonal lines. Is there a way to shift the point in the relevant lists so that they would get connected properly? Thanks. Attaching the file: https://drive.google.com/file/d/0BzTZfXTKDgpZd0Q1MEloMDFKZ28/view?usp=sharing

OK, thanks, I will have a look at this!

Ah yes exactly, the grasshopper document/file, sorry if this was not clear. The problem is that some of the rectangles are not fully projected on top of the surface. Make sure your input curves are exactly flat on the XY plane. Use the "_ProjectToCplane" command in Rhino (delete input objects YES) to make sure. This is for the bottom row of the rectangles, for the sides and top make sure that the rectangular grid matches up`with the lofted surface you generated in the beginning. Make sure the surface is the same size as the gird or bigger NOT smaller. This will result in rectangles not being fully projected on the surface and in return generating weird points for the line to connect to. I hope I'm clear, else let me know, Cheers!

https://drive.google.com/file/d/0BzTZfXTKDgpZS2dhaEVCZDZIMGM/view?usp=sharing I hope the definition means the document.

I mean your Grasshopper definition. Please use https://wetransfer.com/ or something similar to upload your definition and I'll have a look. It's strange it seems as if your points are scrambled. Because the line connects between the rectangle and projected rectangle, just using the wrong set of points.

Hey Arie, thanks for the reply. Sorry, what's a definition and how do I do that? Thanks.

Hi Peeter, That's odd, could you post your definition, so I can have a look? Thanks! Arie