Loose project curve on surface

Scripting
1

The attached script allows you to project a curve onto a surface loosely, which means the resulting curve will have the same amount of control points as the input curve. It will also produce a partial curve, if the control points of the curve miss the surface.

    """
    This script does what the name says: it allows you to loosly
    project a curve on a surface. This means the projected curve has the same
    structure and degree and same amount of control points as the original curve.

    ***********************************
    * script written by Gijs de Zwart *
    * www.studiogijs.nl               *
    * March, 2016                     *
    ***********************************

    """

    import rhinoscriptsyntax as rs
    import Rhino
    import scriptcontext as sc

    def ProjectOnSrfLoose():
        crv=rs.GetObject("select curve to loosely project",rs.filter.curve)
        srf=rs.GetObject("Select surface to loosely project onto", rs.filter.surface)
        if crv==None or srf==None:
            return
        degree=rs.CurveDegree(crv)
        bPeriodic=False
        pts=rs.CurvePoints(crv)
        if rs.IsCurvePeriodic(crv):
            pts=rs.CullDuplicatePoints(pts,0.01)
            bPeriodic=True

        pts_projected=[]
        curveplane=rs.CurvePlane(crv)
        projection_dir=curveplane.ZAxis

        for pt in pts:

            pp=rs.ProjectPointToSurface(pt,srf,projection_dir)
            if len(pp)>0:
                pt_projected=pp[0]
                pts_projected.append(pt_projected)
        if len(pts_projected)<=2:
            return
        if len(pts_projected)<len(pts):
            bPeriodic=False
        nc = Rhino.Geometry.NurbsCurve.Create(bPeriodic,degree,pts_projected)
        sc.doc.Objects.AddCurve(nc)
        sc.doc.Views.Redraw()

    ProjectOnSrfLoose()
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