Project point to surface

Rhino Developer
1

ex
ex.JPG711×361 30.3 KB

Hello everyone!
As shown, I want to project two points vertically onto the surface.
I found a similar function from the RHINO SDK C++, such as: RhinoProjectPointsToBreps() or RhinoProjectPointsToMeshes() .
I have tried to mesh the surface and use function to project the point. But from the results, it is completely useless.
What I want to know is RhinoProjectPointsToMeshes() Is this function really able to project points? Or is there any other way I can know the coordinates of the point vertically projected onto the surface?
Thanks for your advice.

2

Hey,

here is the C# version. For reference you can look at the Surface class in Rhinocommon

https://developer.rhino3d.com/api/RhinoCommon/html/M_Rhino_Geometry_Surface_ClosestPoint.htm

Here is the code, and I also attached the GH file with all data internalized, so if you would like to see a live update, dont forget to input your own points or surface.

  private void RunScript(Surface surface, List<Point3d> pts, ref object A)
  {
    List<Point3d> projectedPoints = new List<Point3d>();
    double u;
    double v;

    for (int i = 0; i < pts.Count; i++)
    {


      bool cp = surface.ClosestPoint(pts[i], out u, out v);

      if(cp)
      {


        Plane plane;

        if (surface.FrameAt(u, v, out plane))
        {
          projectedPoints.Add(plane.Origin);
        }
      }

    }

    A = projectedPoints;
  }

I hope it helps

SrfClosestPts.gh (5.7 KB)

3

Hi @t107408022,

To project one or more points onto a surface, use RhinoProjectPointsToBreps. If you have an ON_Surface, then you can construct a Brep from the surface as follows:

ON_Surface* surface = ...
ON_Brep* brep = ON_Brep::New();
brep->Create(surface);
...
delete brep;

See opennurbs_brep.h for more details.

– Dale