C# Curve.TangentAt方法代码示例

    /**
     * divideCrvsByDeltaTan : Curve[] * double -> LinkedList<Plane>
     * REQUIRES: theta > 0
     * ENSURES: divideCrvsByDeltaTan(crvs, theta) returns a linked list of planes
     *          along the curves s.t. there is a plane at every point along
     *          the curve where the change in the tangent vector between
     *          two points is greater than theta.
    **/
    private IEnumerable<Point3d> DivByAngle(Curve crv, double angle)
    {

      //initialize parameters
      double theta = angle;
      Interval dom = crv.Domain;
      double stepSize = Math.Abs(dom.Length) * Constants.AbsoluteTolerance * Constants.AbsoluteTolerance;

      //initialize list
      List<Point3d> pts = new List<Point3d>();

      Continuity c = Continuity.C1_continuous;
      //initialize data
      
      double rover = dom.Min; //steps along the curve by stepSize

      //Add plane at start point of curve to list
      Point3d pt = crv.PointAt(rover);
      pts.Add(pt);

      //Increment
      Vector3d prevTan = crv.TangentAt(rover);
      double oldRover = rover; //stores the previous rover for comparison
      rover += stepSize;

      while (rover < dom.Max)
      {
        Vector3d currTan = crv.TangentAt(rover);
        //If there is a discontinuity between the oldRover and rover
        //then place a point at the discontinuity and update prevTan.
        double discontinuity;
        bool isDisc = crv.GetNextDiscontinuity(c, oldRover, rover,
          out discontinuity);
        if (isDisc)
        {
          pt = crv.PointAt(discontinuity);
          pts.Add(pt);
          prevTan = crv.TangentAt(discontinuity);
        }

        //If the change in tangent vector is greater than theta,
        //then drop a target at the rover and update prevTan.
        double delta = RhinoMath.ToDegrees(Math.Abs(Vector3d.VectorAngle(prevTan, currTan)));
        if (delta > theta)
        {
          pt = crv.PointAt(rover);
          pts.Add(pt);
          prevTan = currTan;
        }
        //Increment
        oldRover = rover;
        rover += stepSize;
      }

      //Add target at end point of curve
      pt = crv.PointAt(dom.Max);
      pts.Add(pt);
      return pts;
    }

 public Plane horizFrame(Curve C, double t)
 {
     //Create a plane aligned with the world z-axis
     Vector3d Tangent = C.TangentAt(t);
     Vector3d Z = Vector3d.ZAxis;
     Z.Reverse();
     Vector3d Perp = Vector3d.CrossProduct(Z, Tangent);
     Plane frame = new Plane(C.PointAt(t), Tangent, Perp);
     return frame;
 }

                public override BroadRay Directions(int index, int thread, ref Random random, ref Curve Curves, ref double[] DomainPower, ref double Delay, ref Phase_Regime ph, ref int S_ID)
                {
                    double pos = random.NextDouble();
                    int i;

                    Interval t = Curves.Domain;
                    double x = random.NextDouble() * (t[1] - t[0]) + t[0];
                    Point3d P = Curves.PointAt(x);
                    Vector3d f = Curves.TangentAt(x);
                    Vector fore = new Hare.Geometry.Vector(f.X, f.Y, f.Z);

                    double Theta = random.NextDouble() * 2 * System.Math.PI;
                    double Phi = random.NextDouble() * 2 * System.Math.PI;
                    Vector Direction = new Hare.Geometry.Vector(Math.Sin(Theta) * Math.Cos(Phi), Math.Sin(Theta) * Math.Sin(Phi), Math.Cos(Theta));

                    double cosphi = Hare.Geometry.Hare_math.Dot(Direction, fore);
                    double sinphi = Math.Sqrt(1 - cosphi * cosphi);
                    double tanphi =  sinphi/cosphi;
                    double F_r = sinphi * sinphi * Math.Pow((tanphi * tanphi + 1) / (tanphi * tanphi + (1 + tanphi * Math.Tan(delta))), 1.5);

                    double[] power = new double[8];
                    for (int oct = 0; oct < 8; oct++) power[oct] = DomainPower[oct] * reciprocal_velocity * dLinf * F_r;
                    double[] phase = new double[8];
                    if (ph == Phase_Regime.Random) for (int o = 0; o < 8; o++) phase[o] = random.Next() * 2 * Math.PI;
                    else for (int o = 0; o < 8; o++) phase[o] = 0 - Delay * Utilities.Numerics.angularFrequency[o];

                    return new BroadRay(Utilities.PachTools.RPttoHPt(P), Direction, random.Next(), thread, DomainPower, phase, Delay, S_ID);
                }

                public override double[] DirPower(int threadid, int random, Vector Direction, double position, ref Curve Curves, ref double[] DomainPower)
                {
                    X_Event X = new X_Event();
                    double[] RayPower = new double[8];

                    Interval t = Curves.Domain;
                    Point3d P = Curves.PointAt((position/t.Length) + t.Min);
                    Vector3d f = Curves.TangentAt(position);
                    Vector fore = new Hare.Geometry.Vector(f.X, f.Y, f.Z);

                    double cosphi = Hare.Geometry.Hare_math.Dot(Direction, fore);
                    double sinphi = Math.Sqrt(1 - cosphi * cosphi);
                    double tanphi = sinphi / cosphi;
                    double F_r = sinphi * sinphi * Math.Pow((tanphi * tanphi + 1) / (tanphi * tanphi + (1 + tanphi * Math.Tan(delta))), 1.5);

                    for (int oct = 0; oct < 8; oct++)
                    {
                        if (DomainPower[oct] == 0)
                        {
                            RayPower[oct] = 0;
                        }
                        else
                        {
                            RayPower[oct] = DomainPower[oct] * reciprocal_velocity * dLinf * F_r;
                        }
                    }
                    return RayPower;
                }

        private Vector3d CalcDeformedTangent(Curve c, Point3d pt)
        {
            double t;
            if (!c.ClosestPoint(pt, out t))
                throw new Exception();

            else
                return c.TangentAt(t);
        }