forked from bit/DotRecastNetSim
71 lines
2.2 KiB
C#
71 lines
2.2 KiB
C#
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using System;
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using DotRecast.Core;
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namespace DotRecast.Detour
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{
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using static DotRecast.Core.RecastMath;
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/**
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* Calculate the intersection between a polygon and a circle. A dodecagon is used as an approximation of the circle.
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*/
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public class StrictPolygonByCircleConstraint : IPolygonByCircleConstraint
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{
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private const int CIRCLE_SEGMENTS = 12;
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private static float[] unitCircle;
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public float[] Aply(float[] verts, Vector3f center, float radius)
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{
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float radiusSqr = radius * radius;
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int outsideVertex = -1;
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for (int pv = 0; pv < verts.Length; pv += 3)
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{
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if (VDist2DSqr(center, verts, pv) > radiusSqr)
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{
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outsideVertex = pv;
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break;
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}
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}
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if (outsideVertex == -1)
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{
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// polygon inside circle
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return verts;
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}
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float[] qCircle = Circle(center, radius);
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float[] intersection = ConvexConvexIntersection.Intersect(verts, qCircle);
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if (intersection == null && PointInPolygon(center, verts, verts.Length / 3))
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{
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// circle inside polygon
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return qCircle;
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}
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return intersection;
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}
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private float[] Circle(Vector3f center, float radius)
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{
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if (unitCircle == null)
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{
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unitCircle = new float[CIRCLE_SEGMENTS * 3];
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for (int i = 0; i < CIRCLE_SEGMENTS; i++)
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{
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double a = i * Math.PI * 2 / CIRCLE_SEGMENTS;
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unitCircle[3 * i] = (float)Math.Cos(a);
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unitCircle[3 * i + 1] = 0;
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unitCircle[3 * i + 2] = (float)-Math.Sin(a);
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}
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}
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float[] circle = new float[12 * 3];
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for (int i = 0; i < CIRCLE_SEGMENTS * 3; i += 3)
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{
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circle[i] = unitCircle[i] * radius + center.x;
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circle[i + 1] = center.y;
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circle[i + 2] = unitCircle[i + 2] * radius + center.z;
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}
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return circle;
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}
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}
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}
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