Hello, I got two technical questions:
1- I need to project a 3d point from a vector on to a curve
what is the best way for that ? my solution is O(range/tolerance) complexity
which is very slow …
2- when I use ClosetPoint() method of NurbsCurve in Rhino Common
does it use Rhino binary for computing ? or the .Net Frame work ? it’s dam fast ! 
My code:
// Grasshopper Script Instance
#region Usings
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using Rhino;
using Rhino.Geometry;
using Grasshopper;
using Grasshopper.Kernel;
using Grasshopper.Kernel.Data;
using Grasshopper.Kernel.Types;
#endregion
public class Script_Instance : GH_ScriptInstance
{
#region Notes
/*
Members:
RhinoDoc RhinoDocument
GH_Document GrasshopperDocument
IGH_Component Component
int Iteration
Methods (Virtual & overridable):
Print(string text)
Print(string format, params object[] args)
Reflect(object obj)
Reflect(object obj, string method_name)
*/
#endregion
private void RunScript(
Point3d Pta,
Point3d Ptb,
double threshold,
Curve crv,
double range,
ref object a,
ref object b)
{
// Write your logic here
a = test_point(Pta,Ptb,threshold);
b = Point_On_Curve(
Pta,
Ptb-Pta,
crv.ToNurbsCurve(),
range,
threshold
);
}
// Project Point on curve
public Point3d Point_On_Curve(
Point3d input_point,
Vector3d projection_vector,
NurbsCurve input_crv,
double range,
double tolerance
){
projection_vector.Unitize();
projection_vector*=tolerance;
Point3d result = new Point3d();
input_crv.Domain = new Interval(0,1);
double increment = tolerance;
bool exit = false;
while (increment<range)
{
for (double j=0.0;j<=1;j+=0.001)
{
if(test_point((input_point+projection_vector),input_crv.PointAt(j),0.01)){
result = input_point+projection_vector;
exit=true;
break;
}
}
if(exit){
break;
}
projection_vector.Unitize();
projection_vector*=increment;
increment+=tolerance;
Console.WriteLine("{0}", projection_vector.Length);
}
return result;
}
bool test_point( Point3d pt_a, Point3d pt_b,double threshold)
{
if((pt_a-pt_b).Length<=threshold){
return true;
}else{
return false;
}
}
}
PointProjection.gh (11.5 KB)