Brand new to this.
Can I with Rhino create a surface and then extract XYZ coordinate data.
Hi Guy,
You can extract a lot of information from a surface. What exactly are you trying to do and why? (The answers you provide will help me answer your question…)
– Dale
I am machining surface and need to calculate normal and heights. The surface is simply a rectangular surface above an XY plane.
Are you using the standalone version of openNURBS that you downloaded from here? Or are you using the version of openNURBS that comes with Rhino and, thus, you are writing a plug-in for Rhino in C++?
The reason I ask is that the standalone version of openNURBS is designed to read and write Rhino’s 3dm file format. Thus, it does not have many of the features that the version of openNURBS that comes with Rhino has.
http://wiki.mcneel.com/developer/opennurbs/limitations
For example, to determine points on a surface, you might want to use ON_Surface::GetClosestPoint. This function is is not implemented in the standalone version. Calling this function will provide you surface parameter that you can then passed to ON_Surface::NormalAt, which calculates the normal direction of a surface at some parameter.
Does this help?
– Dale
Dale I am looking to create a standalone program that creates a surface from input data.
The language I use is not important.
Hi Guy,
Other than providing you the ability to read and write 3dm files, the openNURBS toolkit probably isn’t going to provide you enough functionality to do what you want, given the limitations I’ve referenced. The immediate problem for you is that the toolkit won’t perform closest point calculations - necessary for any surface evaluation.
– Dale
Hi Dave
I have read parts of books by Les Piegl and Dave Rodgers but I don’t intend to make a career of this math. I was pointed towards Nlib by Solid Modeling Solutions but it is very expensive and has a steep learning curve. From what I can see the functionality that I need is a small subset. Any suggestions?
Guy
Rather than writing a standalone application, have you considered writing a plug-in for Rhino?
– D
Dale
This is not possible because it is used in the control of a CNC.
Porting a file would be a huge pain.
Guy
Hi Guy,
There are 3rd party CNC plug-ins available for Rhino. RhinoCAM is one that comes to mind. I know users like this particular product because they don’t have to export their geometry. They can model and machine from a single application.
The nice thing about writing a plug-in is that we provide all the framework - geometry, display, user-interface, file I/O, etc. All you need to do is do what you do well. 
– Dale
Dale
We use no CAD/CAM software whatsoever.
All custom script code.
Hence the standalone application.
Guy
Got it.
If you need any help with Rhino or developing for Rhino in the future, let me know.
– Dale
Dale
Thanks for the effort, you definitely one of the good guys.
Guy