272 lines
8.9 KiB
C#
272 lines
8.9 KiB
C#
using Microsoft.Xna.Framework;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace Barotrauma
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{
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static class MathUtils
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{
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public static Vector2 SmoothStep(Vector2 v1, Vector2 v2, float amount)
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{
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return new Vector2(
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MathHelper.SmoothStep(v1.X, v2.X, amount),
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MathHelper.SmoothStep(v1.Y, v2.Y, amount));
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}
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public static float Round(float value, float div)
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{
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return (value < 0.0f) ?
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(float)Math.Ceiling(value / div) * div :
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(float)Math.Floor(value / div) * div;
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}
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public static float RoundTowardsClosest(float value, float div)
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{
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return (float)Math.Round(value / div) * div;
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}
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public static float VectorToAngle(Vector2 vector)
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{
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return (float)Math.Atan2(vector.Y, vector.X);
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}
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public static bool IsValid(float value)
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{
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return (!float.IsInfinity(value) && !float.IsNaN(value));
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}
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public static bool IsValid(Vector2 vector)
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{
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return (IsValid(vector.X) && IsValid(vector.Y));
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}
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public static Rectangle ExpandRect(Rectangle rect, int amount)
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{
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return new Rectangle(rect.X - amount, rect.Y + amount, rect.Width + amount * 2, rect.Height + amount * 2);
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}
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public static int VectorOrientation(Vector2 p1, Vector2 p2, Vector2 p)
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{
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// Determinant
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float Orin = (p2.X - p1.X) * (p.Y - p1.Y) - (p.X - p1.X) * (p2.Y - p1.Y);
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if (Orin > 0)
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return -1; // (* Orientation is to the left-hand side *)
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if (Orin < 0)
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return 1; // (* Orientation is to the right-hand side *)
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return 0; // (* Orientation is neutral aka collinear *)
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}
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public static float CurveAngle(float from, float to, float step)
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{
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from = WrapAngleTwoPi(from);
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to = WrapAngleTwoPi(to);
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if (Math.Abs(from - to) < MathHelper.Pi)
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{
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// The simple case - a straight lerp will do.
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return MathHelper.Lerp(from, to, step);
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}
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// If we get here we have the more complex case.
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// First, increment the lesser value to be greater.
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if (from < to)
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from += MathHelper.TwoPi;
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else
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to += MathHelper.TwoPi;
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float retVal = MathHelper.Lerp(from, to, step);
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// Now ensure the return value is between 0 and 2pi
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if (retVal >= MathHelper.TwoPi)
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retVal -= MathHelper.TwoPi;
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return retVal;
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}
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/// <summary>
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/// wrap the angle between 0.0f and 2pi
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/// </summary>
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public static float WrapAngleTwoPi(float angle)
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{
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if (float.IsInfinity(angle) || float.IsNegativeInfinity(angle) || float.IsNaN(angle))
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{
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return 0.0f;
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}
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while (angle < 0)
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angle += MathHelper.TwoPi;
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while (angle >= MathHelper.TwoPi)
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angle -= MathHelper.TwoPi;
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return angle;
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}
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/// <summary>
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/// wrap the angle between -pi and pi
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/// </summary>
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public static float WrapAnglePi(float angle)
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{
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if (float.IsInfinity(angle) || float.IsNegativeInfinity(angle) || float.IsNaN(angle))
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{
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return 0.0f;
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}
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// Ensure that -pi <= angle < pi for both "from" and "to"
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while (angle < -MathHelper.Pi)
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angle += MathHelper.TwoPi;
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while (angle >= MathHelper.Pi)
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angle -= MathHelper.TwoPi;
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return angle;
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}
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public static float GetShortestAngle(float from, float to)
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{
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// Ensure that 0 <= angle < 2pi for both "from" and "to"
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from = WrapAngleTwoPi(from);
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to = WrapAngleTwoPi(to);
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if (Math.Abs(from - to) < MathHelper.Pi)
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{
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return to - from;
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}
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// If we get here we have the more complex case.
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// First, increment the lesser value to be greater.
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if (from < to)
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from += MathHelper.TwoPi;
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else
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to += MathHelper.TwoPi;
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return to - from;
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}
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/// <summary>
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/// solves the angle opposite to side a (parameters: lengths of each side)
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/// </summary>
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public static float SolveTriangleSSS(float a, float b, float c)
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{
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float A = (float)Math.Acos((b * b + c * c - a * a) / (2 * b * c));
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if (float.IsNaN(A)) A = 1.0f;
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return A;
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}
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public static byte AngleToByte(float angle)
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{
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angle = WrapAngleTwoPi(angle);
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angle = angle * (255.0f / MathHelper.TwoPi);
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return Convert.ToByte(angle);
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}
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public static float ByteToAngle(byte b)
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{
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float angle = (float)b;
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angle = angle * (MathHelper.TwoPi / 255.0f);
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return angle;
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}
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/// <summary>
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/// check whether line from a to b is intersecting with line from c to b
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/// </summary>
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public static bool LinesIntersect(Vector2 a, Vector2 b, Vector2 c, Vector2 d)
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{
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float denominator = ((b.X - a.X) * (d.Y - c.Y)) - ((b.Y - a.Y) * (d.X - c.X));
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float numerator1 = ((a.Y - c.Y) * (d.X - c.X)) - ((a.X - c.X) * (d.Y - c.Y));
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float numerator2 = ((a.Y - c.Y) * (b.X - a.X)) - ((a.X - c.X) * (b.Y - a.Y));
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if (denominator == 0) return numerator1 == 0 && numerator2 == 0;
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float r = numerator1 / denominator;
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float s = numerator2 / denominator;
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return (r >= 0 && r <= 1) && (s >= 0 && s <= 1);
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}
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public static bool CircleIntersectsRectangle(Vector2 circlePos, float radius, Rectangle rect)
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{
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Vector2 circleDistance = new Vector2(Math.Abs(circlePos.X - rect.Center.X), Math.Abs(circlePos.Y -rect.Center.Y));
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if (circleDistance.X > (rect.Width / 2 + radius)) { return false; }
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if (circleDistance.Y > (rect.Height / 2 + radius)) { return false; }
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if (circleDistance.X <= (rect.Width / 2)) { return true; }
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if (circleDistance.Y <= (rect.Height / 2)) { return true; }
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float distSqX = circleDistance.X - rect.Width / 2;
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float distSqY = circleDistance.Y - rect.Height / 2;
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float cornerDistanceSq = distSqX * distSqX + distSqY * distSqY;
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return (cornerDistanceSq <= (radius * radius));
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}
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/// <summary>
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/// divide a convex hull into triangles
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/// </summary>
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/// <returns>List of triangle vertices (sorted counter-clockwise)</returns>
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public static List<Vector2[]> TriangulateConvexHull(List<Vector2> vertices, Vector2 center)
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{
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List<Vector2[]> triangles = new List<Vector2[]>();
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int triangleCount = vertices.Count - 2;
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vertices.Sort(new CompareCCW(center));
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int lastIndex = 1;
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for (int i = 0; i < triangleCount; i++)
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{
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Vector2[] triangleVertices = new Vector2[3];
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triangleVertices[0] = vertices[0];
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int k = 1;
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for (int j = lastIndex; j <= lastIndex + 1; j++)
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{
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triangleVertices[k] = vertices[j];
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k++;
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}
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lastIndex += 1;
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triangles.Add(triangleVertices);
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}
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return triangles;
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}
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}
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class CompareCCW : IComparer<Vector2>
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{
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private Vector2 center;
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public CompareCCW(Vector2 center)
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{
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this.center = center;
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}
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public int Compare(Vector2 a, Vector2 b)
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{
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if (a.X - center.X >= 0 && b.X - center.X < 0) return -1;
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if (a.X - center.X < 0 && b.X - center.X >= 0) return 1;
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if (a.X - center.X == 0 && b.X - center.X == 0)
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{
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if (a.Y - center.Y >= 0 || b.Y - center.Y >= 0) return Math.Sign(b.Y - a.Y);
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return Math.Sign(a.Y - b.Y);
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}
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// compute the cross product of vectors (center -> a) x (center -> b)
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float det = (a.X - center.X) * (b.Y - center.Y) - (b.X - center.X) * (a.Y - center.Y);
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if (det < 0) return -1;
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if (det > 0) return 1;
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// points a and b are on the same line from the center
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// check which point is closer to the center
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float d1 = (a.X - center.X) * (a.X - center.X) + (a.Y - center.Y) * (a.Y - center.Y);
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float d2 = (b.X - center.X) * (b.X - center.X) + (b.Y - center.Y) * (b.Y - center.Y);
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return Math.Sign(d2 - d1);
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}
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}
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}
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