Get z at xy for NURBS curve?

[Palle]

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

[SBarrettWalker]

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.

 

Battle dots marionette create loft.vwx

[SimA]

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?

 

@sbarrett

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

 

[SBarrettWalker]

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.

[SimA]

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".

 

Thank you for your help.

[SBarrettWalker]

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.

[SimA]

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?

 

Many thanks for your help

Test.vwx