# Perpendicular lines connecting points on divided curves

Hello everyone,
I am new to grasshopper and i’m trying to use it to create some perpendicular lines through some points on a divided curve. I managed to do it successfully for one line, however i failed to create the others successfully. It would be great if anyone could help show me how this could be done. Attached are some images describing what i need to do, with my grasshopper and rhino files.

It is for a stadium structure,I already made lines L1, i want to create perpendicular lines L2(connecting points on curves C1 and C3), and create lines L3( connecting points on curves C2 and C4).
Is it also possible to create lines L4 and L5 hosted on some points along the created lines L2 and L3?

mcn structure and shell rh5.3dm (1.5 MB)
mcn structure and shell.gh (13.1 KB)

Just to clarify, that sketch is a section view of your stadium right?

yes W.Cervio, it is a section view

I may a have solution, but let me investigate and i’ll update this post with a solution if i find any.

Update:
So there is something about your rhino model that i don’t get, why is the inner top curve only chamfered in half of it corners?
I haven’t fixed the issue, but shown a possible way to do it, if you can manage to have the Plane Curve intersection behave properly.
Look at the point lists included, then you will discover what i mean about the point list being a bit dumb.

If you do manage to fix the PCX component output, the way forward for L4 and L5, is to use “evaluate curve” on L3 and L2, and then just start connecting points.

Best of luck.

Update 2:
It bothered me that something this simple was causing me this amount of trouble.
So i fixed, the solution was to flip the top inner curve.
i’ve included point lists so you can see the logic of the definition.
But in essence, we use planes instead to ensure that the connecting lines are on the same plane.

mcn structure and shell_WCPM.gh (14.1 KB)

thanks for the input, evaluate curve did work like a charm.