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# Intersection points between curves

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Hello Everyone,

I'm just getting started with marionette and I couldn't find a solution to something that I thought would be just another existing node. Maybe I'm not using the correct search words. I'm not sure. I have been trying to retrieve the intersection points between a curve and a set of lines. Like the line-line segment intersect node does but I couldn't see an easy enough way to do it for 2D curves. Can anyone tell me if I'm overlooking something?

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• Marionette Maven

I'm not positive, but it probably doesn't exist yet.

I can look into making one, but it may take me some time.

It's easy to get line intersections since both objects are linear, but with a curve we'll have to extract the equation for the curve.

Is your curve a poly or a NURBS?

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Hello Marissa,

Thank you for replying. My curve is a 2D poly in one case and a simple 2D arc in another case that I would have to use the algorithm. I want to extract the intersection points in a list so that I can use them to create a diagonal grid between. I attached the example where I want to intersect lines with an arc for now.

170112_1710_Marionette_Question.vwx

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• Marionette Maven

Here's a file with a node that will intersect lines with circles (arcs are just segments of circles anyhow)

I haven't tested in any cases other than the one you've provided, but it's a starting point.

170112_1710_Marionette_Question_MFarrell.vwx

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Thank you Marissa!

I hadn't thought of this solution. It works well for both variations that I need. Really appreciated!!!

Cheers!

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• 1 year later...

Hi Marissa I have a similar question,

I would like to find the intersection points between nurbs curves as you mentioned above.

I am making a gridshell structure using contour nodes to create ribs along a nurbs surface.  I then want to find the intersection of the ribs in order to create pin joints at these locations. I have attached my file.

Any help would be appreciated.

gridshell test.vwx

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• Marionette Maven

I've started on this, but hit a bump that I need to spend some more time on.

I'm attaching my progress below.

The issue is that there are still some outlying points that I need to find a way to filter out; otherwise, I believe it's performing pretty well. Please let me know if you find any issues.

gridshell test_MFarrell.vwx

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That's great thank you! Very useful to see how you did it - I am learning a lot.

Yes, it's working well other than the bounding box - I am looking for a solution too but for now can definitely work with it.

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• Vectorworks, Inc Employee

Here is an option for the issue of the bounding box. I found points along the edges of the surface and created a 2D poly from those points.

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@sbarrett  Thanks, works perfectly.

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• 1 year later...

Hello everybody

I would like to process a nurbs surface in such a way that I can then generate a G code for a 5-axis CNC.

Sure you can answer all my questions.

I would like to provide the nurbs area with coordinates (hand sketch).

1. The coordinates should return position values for x, y, z.

2. The start (00) should be able to be defined by the user.

3. The user should be able to define the mesh size himself.

The aim is to define the center point (00, 01, 10, 11 --> 5.5).

1. Point 3D --> x, y, z

2. Vector 3D --> x, y, z

Thank you in advance.

Greetings from switzerland

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