Get z at xy for NURBS curve?

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What is the method for analyzing a NURBS curve? I want to get the z value of the NURBS curve at specific coordinates as shown in the file. Is the node GET Z AT XY useful for that? Or is that only for surfaces?

Palle

Battle dots marionette (forum).vwx

• Vectorworks, Inc Employee

Unfortunately, the Get Z at XY probably won't work because a NURBS curve likely doesn't have an actual thickness. I created a work around that might work - I created a loft based on the curve, used the Get Z at XY node and then deleted the loft.

• 2 years later...

Hello everyone

I find this workaround interesting.

If the Nurbs curve is bent in XYZ then I would need to duplicate the Locus points along the path. correct?

Is there some way to get the alignment of a Nurbs surface at point XY --> Get Z at XY "Get Degree"?

Have a nice day

Greetings from switzerland

• Vectorworks, Inc Employee

You can extract a point anywhere along a NURBS curve and get the Z value, but the point has to be relative to the length of NURBS curve, not the coordinate space. Get degree gives you the curvature of the NURBS curve at that point, I don't think it will get you the Z value.

Is it possible with "Get Degree" to get the curvature of a NURBS surface (not a curve) at a certain point, for example at the locus?

Alternatively, I would have to create objects and read their rotation with "Get 3D Orientation".

• Vectorworks, Inc Employee

I don't think Get Degree get you any useful info. It is a degree of curvature that is specific to NURBS, so it will be a value of 1 if the point is a sharp angle, 2, or 3, etc. for less sharp angles - it is a value that is specific to NURBS geometry and not a real-world degree value. I believe what you are looking for is the Normal value of a Surface at a certain point. There are NURBS nodes that give you the Normal - the direction of the vector that is normal to the surface at that point. You can use this value to orient objects along a surface, for example. I can't remember the exact name of the node or nodes, but it should have the word Normal in either the name or the output value.

Hello everyone

After spending some time searching, I think I've found a workable solution. Everything is trial and error.

I can now align an object at a 90 ° angle on any surface.

The attached file works with a NURBS surface and a 3D object (example).

I found the special node "PtArrayStartEnd v002" in a network of @DomC. Thank you.

Is there a way to calculate the workflow and do without the graphic elements?

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