/// <summary>Determines whether the specified point exists within this triangle's sides.</summary>
/// <param name="p">An object of type System.Drawing.Point to test.</param>
/// <returns>A bool value indicating true if the specified point is within the triangle. Otherwise, false.</returns>
public bool Contains(PointF p)
{
LineF ac = new LineF(this.PointA, this.PointC);
LineF ab = new LineF(this.PointA, this.PointB);
LineF cb = new LineF(this.PointB, this.PointC);
float da = LineF.FindDistance(this.PointA, p);
float db = LineF.FindDistance(this.PointB, p);
float dc = LineF.FindDistance(this.PointC, p);
float dai = LineF.FindDistance(this.PointA, LineF.FindIntersect(cb, new LineF(this.PointA, p)));
float dbi = LineF.FindDistance(this.PointB, LineF.FindIntersect(ac, new LineF(this.PointB, p)));
float dci = LineF.FindDistance(this.PointC, LineF.FindIntersect(ab, new LineF(this.PointC, p)));
return((da < dai) && (db < dbi) && (dc < dci));
}
public static float AreaOfIntersect(CircleF val1, CircleF val2)
{
// First, we find the distance between the two circle's centers.
double c = LineF.FindDistance(val1.Center, val2.Center);
// Then, we use the Law of Cosines to find the angle of the points
// at which the two cirlces touch from the circles' centers.
// cos(theta) = (r2^2 + c^2 - r1^2) / (2 * r1 * c)
double theta = System.Math.Sin((System.Math.Pow(val2.Radius, 2) + System.Math.Pow(c, 2) - System.Math.Pow(val1.Radius, 2)) / (2 * val2.Radius * c));
// Now we find the distance from the midpoint of the chord (the line
// segment drawn between the two intersection points) to the center
// of either circle. This value will always be the same no matter
// which circle you calculate to.
double d = val1.Radius * System.Math.Cos(theta / 2);
// Now, the each 'segment' can be seen as two triangles back-to-back
// with an arched cap. This arched cap is the area of intersect.
// (r1^2 * arccos(d / r1)) - (d * sqrt(r1^2 - d^2))
double area = (System.Math.Pow(val1.Radius, 2) * System.Math.Acos(d / val1.Radius)) - (d * System.Math.Sqrt(System.Math.Pow(val1.Radius, 2) - System.Math.Pow(d, 2)));
// Since the area of intersect is two of these arched caps back-to-back,
// the total area of intersect is twice "area".
return((float)(area * 2));
}
public CircleF(PointF center, PointF point)
{
this.Center = center;
this.Radius = LineF.FindDistance(center, point);
}
public static int FindDistance(Point p1, Point p2)
{
return((int)LineF.FindDistance(new LineF(
new PointF((float)p1.X, (float)p1.Y),
new PointF((float)p2.X, (float)p2.Y))));
}
