/// <summary>
/// Reflect line in given plane
/// </summary>
public virtual Line3d ReflectIn(Plane3d s)
{
return(new Line3d(this.Point.ReflectIn(s), this.Direction.ReflectIn(s)));
}
/// <summary>
/// Reflect triangle in given plane
/// </summary>
public Triangle ReflectIn(Plane3d s)
{
return(new Triangle(_a.ReflectIn(s), _b.ReflectIn(s), _c.ReflectIn(s)));
}
/// <summary>
/// Reflect ray in given plane
/// </summary>
public Ray3d ReflectIn(Plane3d s)
{
return(new Ray3d(this.Point.ReflectIn(s), this.Direction.ReflectIn(s)));
}
/// <summary>
/// Orthogonal projection of the circle to plane
/// </summary>
public Ellipse ProjectionTo(Plane3d s)
{
return(this.ToEllipse.ProjectionTo(s));
}
/// <summary>
/// Reflect circle in given plane
/// </summary>
public Circle3d ReflectIn(Plane3d s)
{
return(new Circle3d(this.Center.ReflectIn(s), this.R, this.Normal.ReflectIn(s)));
}
/// <summary>
/// Reflect sphere in given plane
/// </summary>
public Sphere ReflectIn(Plane3d s)
{
return(new Sphere(this.Center.ReflectIn(s), this.R));
}
/// <summary>
/// Reflect segment in given plane
/// </summary>
public virtual Segment3d ReflectIn(Plane3d s)
{
return(new Segment3d(P1.ReflectIn(s), P2.ReflectIn(s)));
}
/// <summary>
/// Reflect plane in given plane
/// </summary>
public Plane3d ReflectIn(Plane3d s)
{
return(new Plane3d(this.Point.ReflectIn(s), this.Normal.ReflectIn(s)));
}
/// <summary>
/// Orthogonal projection of the sphere to the plane
/// </summary>
public Circle3d ProjectionTo(Plane3d s)
{
Point3d p = this.Center.ProjectionTo(s);
return(new Circle3d(p, this.R, s.Normal));
}
/// <summary>
/// Reflect ellipse in given plane
/// </summary>
public Ellipse ReflectIn(Plane3d s)
{
return(new Ellipse(this.Center.ReflectIn(s), _v1.ReflectIn(s), _v2.ReflectIn(s)));
}
/// <summary>
/// Intersection of ellipse with plane.
/// Returns 'null' (no intersection) or object of type 'Ellipse', 'Point3d' or 'Segment3d'.
/// </summary>
public object IntersectionWith(Plane3d s)
{
if (this.Normal.IsParallelTo(s.Normal))
{
if (this.Center.BelongsTo(s))
{
// coplanar objects
return(this.Copy());
}
else
{
// parallel objects
return(null);
}
}
else
{
Line3d l = (Line3d)s.IntersectionWith(new Plane3d(this.Center, this.Normal));
Coord3d local_coord = new Coord3d(this.Center, this._v1, this._v2);
Point3d p = l.Point.ConvertTo(local_coord);
Vector3d v = l.Direction.ConvertTo(local_coord);
double a = this.A;
double b = this.B;
if (Abs(v.Y / v.X) > 100)
{
// line is almost vertical, rotate local coord
local_coord = new Coord3d(this.Center, this._v2, this._v1);
p = l.Point.ConvertTo(local_coord);
v = l.Direction.ConvertTo(local_coord);
a = this.B;
b = this.A;
}
// Find intersection of line and ellipse (2D)
// Solution from: http://www.ambrsoft.com/TrigoCalc/Circles2/Ellipse/EllipseLine.htm
// Line equation in form: y = mx + c
double m = v.Y / v.X;
double c = p.Y - m * p.X;
double amb = Math.Pow(a, 2) * Math.Pow(m, 2) + Math.Pow(b, 2);
double det = amb - Math.Pow(c, 2);
if (det < -GeometRi3D.Tolerance)
{
return(null);
}
else if (GeometRi3D.AlmostEqual(det, 0))
{
double x = -Math.Pow(a, 2) * m * c / amb;
double y = Math.Pow(b, 2) * c / amb;
return(new Point3d(x, y, 0, local_coord));
}
else
{
double x1 = (-Math.Pow(a, 2) * m * c + a * b * Sqrt(det)) / amb;
double x2 = (-Math.Pow(a, 2) * m * c - a * b * Sqrt(det)) / amb;
double y1 = (Math.Pow(b, 2) * c + a * b * m * Sqrt(det)) / amb;
double y2 = (Math.Pow(b, 2) * c - a * b * m * Sqrt(det)) / amb;
return(new Segment3d(new Point3d(x1, y1, 0, local_coord), new Point3d(x2, y2, 0, local_coord)));
}
}
}
/// <summary>
/// Intersection of ellipsoid with plane.
/// Returns 'null' (no intersection) or object of type 'Point3d' or 'Ellipse'.
/// </summary>
public object IntersectionWith(Plane3d plane)
{
// Solution 1:
// Peter Paul Klein
// On the Ellipsoid and Plane Intersection Equation
// Applied Mathematics, 2012, 3, 1634-1640 (DOI:10.4236/am.2012.311226)
// Solution 2:
// Sebahattin Bektas
// Intersection of an Ellipsoid and a Plane
// International Journal of Research in Engineering and Applied Sciences, VOLUME 6, ISSUE 6 (June, 2016)
Coord3d lc = new Coord3d(_point, _v1, _v2, "LC1");
plane.SetCoord(lc);
double Ax, Ay, Az, Ad;
double a, b, c;
if (Abs(plane.C) >= Abs(plane.A) && Abs(plane.C) >= Abs(plane.B))
{
a = this.A; b = this.B; c = this.C;
}
else
{
lc = new Coord3d(_point, _v2, _v3, "LC2");
plane.SetCoord(lc);
if (Abs(plane.C) >= Abs(plane.A) && Abs(plane.C) >= Abs(plane.B))
{
a = this.B; b = this.C; c = this.A;
}
else
{
lc = new Coord3d(_point, _v3, _v1, "LC3");
plane.SetCoord(lc);
a = this.C; b = this.A; c = this.B;
}
}
Ax = plane.A; Ay = plane.B; Az = plane.C; Ad = plane.D;
double tmp = (Az * Az * c * c);
double AA = 1.0 / (a * a) + Ax * Ax / tmp;
double BB = 2.0 * Ax * Ay / tmp;
double CC = 1.0 / (b * b) + Ay * Ay / tmp;
double DD = 2.0 * Ax * Ad / tmp;
double EE = 2.0 * Ay * Ad / tmp;
double FF = Ad * Ad / tmp - 1.0;
double det = 4.0 * AA * CC - BB * BB;
if (GeometRi3D.AlmostEqual(det, 0))
{
return(null);
}
double X0 = (BB * EE - 2 * CC * DD) / det;
double Y0 = (BB * DD - 2 * AA * EE) / det;
double Z0 = -(Ax * X0 + Ay * Y0 + Ad) / Az;
Point3d P0 = new Point3d(X0, Y0, Z0, lc);
if (P0.IsOnBoundary(this))
{
// the plane is tangent to ellipsoid
return(P0);
}
else if (P0.IsInside(this))
{
Vector3d q = P0.ToVector.ConvertTo(lc);
Matrix3d D1 = Matrix3d.DiagonalMatrix(1 / a, 1 / b, 1 / c);
Vector3d r = plane.Normal.ConvertTo(lc).OrthogonalVector.Normalized;
Vector3d s = plane.Normal.ConvertTo(lc).Cross(r).Normalized;
double omega = 0;
double qq, qr, qs, rr, ss, rs;
if (!GeometRi3D.AlmostEqual((D1 * r) * (D1 * s), 0))
{
rr = (D1 * r) * (D1 * r);
rs = (D1 * r) * (D1 * s);
ss = (D1 * s) * (D1 * s);
if (GeometRi3D.AlmostEqual(rr - ss, 0))
{
omega = PI / 4;
}
else
{
omega = 0.5 * Atan(2.0 * rs / (rr - ss));
}
Vector3d rprim = Cos(omega) * r + Sin(omega) * s;
Vector3d sprim = -Sin(omega) * r + Cos(omega) * s;
r = rprim;
s = sprim;
}
qq = (D1 * q) * (D1 * q);
qr = (D1 * q) * (D1 * r);
qs = (D1 * q) * (D1 * s);
rr = (D1 * r) * (D1 * r);
ss = (D1 * s) * (D1 * s);
double d = qq - qr * qr / rr - qs * qs / ss;
AA = Sqrt((1 - d) / rr);
BB = Sqrt((1 - d) / ss);
return(new Ellipse(P0, AA * r, BB * s));
}
else
{
return(null);
}
}
/// <summary>
/// Reflect point in given plane
/// </summary>
public Point3d ReflectIn(Plane3d s)
{
Vector3d v = new Vector3d(this, this.ProjectionTo(s));
return(this.Translate(2 * v));
}
/// <summary>
/// Returns shortest distance from point to the plane
/// </summary>
public double DistanceTo(Plane3d s)
{
s.SetCoord(this.Coord);
return(Abs(X * s.A + Y * s.B + Z * s.C + s.D) / Sqrt(s.A * s.A + s.B * s.B + s.C * s.C));
}