# Intersection between two curves (Galapagos)

Hello, I search for a way to make this two curves cross, like here:

but every time I make a try with Galapagos, it didn’t find the intersection points and the solution ist this:

I want Galapagos tho move the endpoints in Y Direction to find the intersection

this are the datas:
Leichtbau.3dm (2.7 MB)
GRH.gh (26.3 KB)

Any help will be great

this is not a good task for Galapagos because this is more a sort of “hit or miss” situation, where you can’t evaluate how well or badly you have missed in such a way next generation might improve based on the result of previous one

Galapagos is an evolutionary solver, which very often is interpreted as a “brute force machine” (I -in first place- have been using it like that for a long time… and sometimes I still do…)

you have two arcs, one of them is fixed in space, the other one can have its start and end points moved along Y on a certain interval

why trying all the possible arc-start-point and arc-end-point combinations, if you already know from the beginning there’s just exactly one given solution for each arc-B point, for which the two arcs are intersecting in exactly two points?

this part, for each customizable B-mid-arc point, gives you only the A and C points on XY plane that satisfy the “the two arcs are intersecting in two points” condition

it starts from the idea that, because the two arcs are planar, if they intersect then for sure will intersect on the line identified by the intersection of the very planes they lie on

1. we find the plane|plane intersection line (white) and intersect it with the arc which is fixed in space (green points)

2. and then we build a second arc that pass through our point B, and those two points, which for sure intersects the second arc

3. then extend this arc until it for sure touches the XY plane, and 4) find the intersection points (yellow) with the XY plane

4. at the end we can even “redraw” the perfect arc with the new A and C points which lie on the XY plane and our point B

GRH_Re.gh (33.5 KB)

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Thank you very very much this solution is way better than Galapagos.
It works so good just what im searching for

Maybe you can help me with this question too if you want?

I want the surface to be offseted to the middle (on both sides), like that the edges of the surface moves to the middle point. The white line should be an empty space between the anchor and the surface.
Membran.gh (19.3 KB)

this is the first thing that came to my mind, there could easily be better solutions

1. find start/mid/end points (A, B, C) on the arc to rebuilt with offset

2. move point B in direction of:

3. average of (A, C) by desired amount

4. rebuild arc using A + moved B + C

 this does that for both arcs: Membran_Re.gh (27 KB)

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Thank you, you are very helpful.
And I like it that you not only send the solution. Because you send the explanation too and so I can understand it better and learn it

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