├── AllGeometry.cs
├── DistanceToLine.cs
└── PointInTriangle.cs


/AllGeometry.cs:
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 1 | using System;
 2 | 
 3 | public static class Geometry
 4 | {
 5 | 
 6 | 	/// Distance of point C from the line passing through points A and B.
 7 | 	public static double DistanceFromPointToLine(Point a, Point b, Point c)
 8 | 	{
 9 | 		double s1 = -b.y + a.y;
10 | 		double s2 = b.x - a.x;
11 | 		return Math.Abs((c.x - a.x) * s1 + (c.y - a.y) * s2) / Math.Sqrt(s1*s1 + s2*s2);
12 | 	}
13 | 
14 | 	/// Psuedo distance of point C from the line passing through points A and B.
15 | 	/// This is not the actual distance value, but a further point will always have a higher value than a nearer point.
16 | 	/// Faster than calculating the actual distance. Useful for sorting.
17 | 	public static double PseudoDistanceFromPointToLine(Point a, Point b, Point c)
18 | 	{
19 | 		return Math.Abs((c.x - a.x) * (-b.y + a.y) + (c.y - a.y) * (b.x - a.x));
20 | 	}
21 | 
22 | 	/// Determines which side point C lies of the line passing through points A and B
23 | 	/// Returns +1 if on one side of line, -1 if on the other, and 0 if it lies exactly on the line
24 | 	public static int SideOfLine(Point a, Point b, Point c)
25 | 	{
26 | 		return Math.Sign((c.x - a.x) * (-b.y + a.y) + (c.y - a.y) * (b.x - a.x));
27 | 	}
28 | 
29 | 	/// Determines whether point P is inside the triangle ABC
30 | 	public static bool PointInTriangle(Point a, Point b, Point c, Point p)
31 | 	{
32 | 		double s1 = c.y - a.y;
33 | 		double s2 = c.x - a.x;
34 | 		double s3 = b.y - a.y;
35 | 		double s4 = p.y - a.y;
36 | 
37 | 		double w1 = (a.x * s1 + s4 * s2 - p.x * s1) / (s3 * s2 - (b.x-a.x) * s1);
38 | 		double w2 = (s4- w1 * s3) / s1;
39 | 		return w1 >= 0 && w2 >= 0 && (w1 + w2) <= 1;
40 | 	}
41 | }
42 | 
43 | public struct Point
44 | {
45 | 	public readonly double x;
46 | 	public readonly double y;
47 | 
48 | 	public Point(double x, double y)
49 | 	{
50 | 		this.x = x;
51 | 		this.y = y;
52 | 	}
53 | }
54 | 


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/DistanceToLine.cs:
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 1 | using System;
 2 | 
 3 | public static class Geometry
 4 | {
 5 | 
 6 | 	// Explanation of below methods:
 7 | 	// youtu.be/KHuI9bXZS74?list=PLFt_AvWsXl0cD2LPxcjxVjWTQLxJqKpgZ
 8 | 	 
 9 | 
10 | 	/// Distance of point C from the line passing through points A and B.
11 | 	public static double DistanceFromPointToLine(Point a, Point b, Point c)
12 | 	{
13 | 		double s1 = -b.y + a.y;
14 | 		double s2 = b.x - a.x;
15 | 		return Math.Abs((c.x - a.x) * s1 + (c.y - a.y) * s2) / Math.Sqrt(s1*s1 + s2*s2);
16 | 	}
17 | 
18 | 	/// Psuedo distance of point C from the line passing through points A and B.
19 | 	/// This is not the actual distance value, but a further point will always have a higher value than a nearer point.
20 | 	/// Faster than calculating the actual distance. Useful for sorting.
21 | 	public static double PseudoDistanceFromPointToLine(Point a, Point b, Point c)
22 | 	{
23 | 		return Math.Abs((c.x - a.x) * (-b.y + a.y) + (c.y - a.y) * (b.x - a.x));
24 | 	}
25 | 
26 | 	/// Determines which side point C lies of the line passing through points A and B
27 | 	/// Returns +1 if on one side of line, -1 if on the other, and 0 if it lies exactly on the line
28 | 	public static int SideOfLine(Point a, Point b, Point c)
29 | 	{
30 | 		return Math.Sign((c.x - a.x) * (-b.y + a.y) + (c.y - a.y) * (b.x - a.x));
31 | 	}
32 | }
33 | 
34 | public struct Point
35 | {
36 | 	public readonly double x;
37 | 	public readonly double y;
38 | 
39 | 	public Point(double x, double y)
40 | 	{
41 | 		this.x = x;
42 | 		this.y = y;
43 | 	}
44 | }


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/PointInTriangle.cs:
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 1 | using System;
 2 | 
 3 | public static class Geometry
 4 | {
 5 | 
 6 | 	// Explanation of PointInTriangle method:
 7 | 	// youtu.be/HYAgJN3x4GA?list=PLFt_AvWsXl0cD2LPxcjxVjWTQLxJqKpgZ
 8 | 	 
 9 | 	/// Determines whether point P is inside the triangle ABC
10 | 	public static bool PointInTriangle(Point A, Point B, Point C, Point P)
11 | 	{
12 | 			double s1 = C.y - A.y;
13 | 			double s2 = C.x - A.x;
14 | 			double s3 = B.y - A.y;
15 | 			double s4 = P.y - A.y;
16 | 
17 | 			double w1 = (A.x * s1 + s4 * s2 - P.x * s1) / (s3 * s2 - (B.x-A.x) * s1);
18 | 			double w2 = (s4- w1 * s3) / s1;
19 | 			return w1 >= 0 && w2 >= 0 && (w1 + w2) <= 1;
20 | 	}
21 | 	
22 | }
23 | 
24 | public struct Point
25 | {
26 | 	public readonly double x;
27 | 	public readonly double y;
28 | 
29 | 	public Point(double x, double y)
30 | 	{
31 | 		this.x = x;
32 | 		this.y = y;
33 | 	}
34 | }
35 | 


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