代码合并
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MuHua-123
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using System.Collections;
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using System.Collections.Generic;
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using UnityEngine;
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/// <summary>
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/// 算法：耳切法
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/// 依据：简单多边形的双耳定理
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/// </summary>
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public class AlgorithmPolygon : ModuleAlgorithm<DataPlate> {
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/// <summary> 算法：耳切法 </summary>
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public AlgorithmPolygon() { }
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public enum AngleType {
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/// <summary> 平角 = 180 </summary>
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StraightAngle = 0,
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/// <summary> 优角 >180 </summary>
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ReflexAngle = 1,
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/// <summary> 劣角 <180 </summary>
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InferiorAngle = 2
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}
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public class PointNode {
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public int index;
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public Vector2 Position;
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public Vector2 PreviousPosition;
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public Vector2 NextPosition;
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}
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public class Triangle {
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public Vector2 a;
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public Vector2 b;
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public Vector2 c;
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}
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public override void Compute(DataPlate data) {
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List<Vector2> edgePoints = new List<Vector2>(data.edgePoints);
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List<Triangle> polygons = new List<Triangle>();
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Vector2[] allArray = edgePoints.ToArray();
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bool isClockWise = IsClockWise(allArray);
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//耳切法生成三角形
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ComputeEarTriangle(polygons, edgePoints, allArray, isClockWise);
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MergeTriangles(data, polygons);
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}
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/// <summary> 循环计算耳点 </summary>
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public void ComputeEarTriangle(List<Triangle> polygons, List<Vector2> edgePoints, Vector2[] allArray, bool isClockWise) {
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List<Triangle> temp = ComputeEarTriangle(edgePoints, allArray, isClockWise);
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if (temp.Count == 0) { return; }
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polygons.AddRange(temp);
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ComputeEarTriangle(polygons, edgePoints, allArray, isClockWise);
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}
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/// <summary> 计算一个耳点 </summary>
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public List<Triangle> ComputeEarTriangle(List<Vector2> edgePoints, Vector2[] allArray, bool isClockWise) {
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Vector2[] array = edgePoints.ToArray();
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List<Triangle> polygons = new List<Triangle>();
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for (int i = 0; i < array.Length; i++) {
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PointNode pointNode = CreatePointNode(i, array);
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AngleType angleType = GetAngleType(pointNode, isClockWise);
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// 等于180，不可能为耳点
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if (angleType == AngleType.StraightAngle) { continue; }
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// 大于180，不可能为耳点
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if (angleType == AngleType.ReflexAngle) { continue; }
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// 包含其他点，不可能为耳点
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if (IsInsideTriangle(pointNode, allArray)) { continue; }
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// 包含其他耳点，不可能成为耳点
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if (!IsInsideEarTriangle(pointNode, edgePoints)) { continue; }
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edgePoints.Remove(pointNode.Position);
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polygons.Add(CreateTriangle(pointNode));
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}
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return polygons;
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}
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/// <summary> 创建节点 </summary>
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public PointNode CreatePointNode(int index, Vector2[] array) {
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int maxIndex = array.Length;
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PointNode pointNode = new PointNode();
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pointNode.index = index;
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pointNode.PreviousPosition = array[NormalIndex(index - 1, maxIndex)];
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pointNode.Position = array[NormalIndex(index + 0, maxIndex)];
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pointNode.NextPosition = array[NormalIndex(index + 1, maxIndex)];
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return pointNode;
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}
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/// <summary> 计算三角形内是否包含其他点 </summary>
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public bool IsInsideTriangle(PointNode node, Vector2[] array) {
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for (int i = 0; i < array.Length; i++) {
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if (array[i] == node.Position) { continue; }
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if (array[i] == node.PreviousPosition) { continue; }
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if (array[i] == node.NextPosition) { continue; }
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if (IsInsideTriangle(node, array[i])) { return true; }
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}
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return false;
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}
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/// <summary> 计算三角形内是否包含其他点 </summary>
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public bool IsInsideEarTriangle(PointNode node, List<Vector2> edgePoints) {
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if (!edgePoints.Contains(node.Position)) { return false; }
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if (!edgePoints.Contains(node.PreviousPosition)) { return false; }
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if (!edgePoints.Contains(node.NextPosition)) { return false; }
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return true;
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}
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/// <summary> 从节点创建三角形 </summary>
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public Triangle CreateTriangle(PointNode node) {
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Triangle triangle = new Triangle();
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triangle.a = node.Position;
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triangle.b = node.PreviousPosition;
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triangle.c = node.NextPosition;
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return triangle;
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}
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/// <summary> 合并三角形 </summary>
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public void MergeTriangles(DataPlate data, List<Triangle> polygons) {
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//创建数据容器
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List<Vector3> vertices = new List<Vector3>();
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List<Vector2> uv = new List<Vector2>();
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List<int> triangles = new List<int>();
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//三角形合并
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for (int i = 0; i < polygons.Count; i++) {
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Vector3 a = polygons[i].a;
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int aIndex = vertices.Count - 1;
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if (!vertices.Contains(a)) { vertices.Add(a); aIndex = vertices.Count - 1; }
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else { aIndex = vertices.IndexOf(a); }
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Vector3 b = polygons[i].b;
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int bIndex = vertices.Count - 1;
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if (!vertices.Contains(b)) { vertices.Add(b); bIndex = vertices.Count - 1; }
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else { bIndex = vertices.IndexOf(b); }
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Vector3 c = polygons[i].c;
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int cIndex = vertices.Count - 1;
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if (!vertices.Contains(c)) { vertices.Add(c); cIndex = vertices.Count - 1; }
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else { cIndex = vertices.IndexOf(c); }
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triangles.Add(aIndex);
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triangles.Add(bIndex);
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triangles.Add(cIndex);
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}
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//展开uv (顶点去掉z坐标就是未缩放的平面UV)
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for (int i = 0; i < vertices.Count; i++) { uv.Add(vertices[i]); }
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//附加数据
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data.vertices = vertices;
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data.uv = uv;
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data.triangles = triangles;
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}
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/// <summary> 头尾循环标准化索引 </summary>
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public static int NormalIndex(int index, int maxIndex) {
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if (maxIndex == 0) { Debug.LogError("错误索引：maxIndex = 0"); return 0; }
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if (index < 0) { return NormalIndex(index + maxIndex, maxIndex); }
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if (index >= maxIndex) { return NormalIndex(index - maxIndex, maxIndex); }
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return index;
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}
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/// <summary> 当前的点方向是否为顺时针 </summary>
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public static bool IsClockWise(Vector2[] array) {
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// 通过计算叉乘来确定方向
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float sum = 0f;
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double count = array.Length;
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Vector3 va, vb;
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for (int i = 0; i < array.Length; i++) {
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va = array[i];
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vb = (i == count - 1) ? array[0] : array[i + 1];
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sum += va.x * vb.y - va.y * vb.x;
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}
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return sum < 0;
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}
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/// <summary> 判断角的类型 </summary>
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public static AngleType GetAngleType(PointNode node, bool isClockWise) {
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// 角度是否小于180
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// oa & ob 之间的夹角，（右手法则）
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// 逆时针顺序是相反的
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Vector2 o = node.Position;
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Vector2 a = node.PreviousPosition;
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Vector2 b = node.NextPosition;
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float f = (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);
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bool flag = isClockWise ? f > 0 : f < 0;
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if (f == 0) { return AngleType.StraightAngle; }
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else if (flag) { return AngleType.InferiorAngle; }
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else { return AngleType.ReflexAngle; }
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}
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/// <summary> p点是否在点和其左右两个点组成的三角形内,或ca,cb边上 </summary>
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public static bool IsInsideTriangle(PointNode node, Vector2 p) {
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// p点是否在abc三角形内
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Vector2 a = node.PreviousPosition;
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Vector2 b = node.NextPosition;
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Vector2 c = node.Position;
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float c1 = (b.x - a.x) * (p.y - b.y) - (b.y - a.y) * (p.x - b.x);
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float c2 = (c.x - b.x) * (p.y - c.y) - (c.y - b.y) * (p.x - c.x);
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float c3 = (a.x - c.x) * (p.y - a.y) - (a.y - c.y) * (p.x - a.x);
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return (c1 > 0f && c2 >= 0f && c3 >= 0f) || (c1 < 0f && c2 <= 0f && c3 <= 0f);
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}
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}
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