mirror of
https://gitee.com/jisol/jisol-game/
synced 2025-06-26 03:14:47 +00:00
315 lines
12 KiB
C#
315 lines
12 KiB
C#
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using System.Collections.Generic;
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using JNGame.Math;
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namespace JNGame.PathFinding
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{
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/// <summary>
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/// 二叉空间分割树节点
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/// </summary>
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public partial class BspTreeNode
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{
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/// <summary>
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/// 划分到三角形数小于此则停止，可以性能测试下，选择一个合适的值
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/// </summary>
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private const int kMinTriangleCount = 3;
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/// <summary>
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/// 找到树叶节点，向上取三层，获取包含的三角形，用于查找落位阻挡点的临近三角形
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/// </summary>
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private const int kNearestDeepSearch = 3;
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/// <summary>
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/// 当前节点中包含的三角形数据
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/// </summary>
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public List<TriangleRef> tris;
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/// <summary>
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/// 当前节点的子节点
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/// </summary>
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private BspTreeNode[] m_Children;
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/// <summary>
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/// 当前节点的树深
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/// </summary>
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public int depth = 0;
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/// <summary>
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/// 节点的切割线
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/// </summary>
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public SplitLine splitLine;
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/// <summary>
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/// 是否是叶子节点
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/// </summary>
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public bool IsLeaf => m_Children == null;
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/// <summary>
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/// 左子树
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/// </summary>
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public BspTreeNode LeftChild => m_Children?[0];
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/// <summary>
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/// 右子树
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/// </summary>
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public BspTreeNode RightChild => m_Children?[1];
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/// <summary>
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/// 获取指定坐标所在的三角形索引
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/// </summary>
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/// <param name="pos"></param>
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/// <returns></returns>
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public int GetTriangle(in LVector2 pos, out int searchDeep, out List<TriangleRef> triangeGroup)
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{
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if (IsLeaf)
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{
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searchDeep = -1;
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triangeGroup = null;
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foreach (var tri in tris)
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{
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if (tri.Contain(pos))
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{
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return tri.index;
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}
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}
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searchDeep = kNearestDeepSearch;
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return -1;
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}
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else
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{
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var isLeft = LVector2.Cross(splitLine.vertexB - splitLine.vertexA, pos - splitLine.vertexA) >= 0;
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if (isLeft)
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{
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int targetIndex = LeftChild.GetTriangle(pos, out searchDeep, out triangeGroup);
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if (targetIndex == -1)
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{
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--searchDeep;
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if (searchDeep == 0)
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{
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triangeGroup = tris;
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}
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}
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return targetIndex;
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}
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else
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{
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int targetIndex = RightChild.GetTriangle(pos, out searchDeep, out triangeGroup);
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if (targetIndex == -1)
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{
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--searchDeep;
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if (searchDeep == 0)
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{
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triangeGroup = tris;
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}
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}
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return targetIndex;
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}
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}
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}
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/// <summary>
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/// 初始化二叉空间树的节点
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/// </summary>
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/// <param name="tris"></param>
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/// <param name="depth"></param>
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public void Init(List<TriangleRef> tris, int depth = 0)
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{
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this.depth = depth;
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this.tris = tris;
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if (tris.Count <= kMinTriangleCount)
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{ // 三角形数少于指标，停止
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return;
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}
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if (depth > 20)
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{ // 树深超过20层，停止
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return;
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}
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// 选择分割线
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splitLine = PickSplitLine(tris);
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m_Children = new BspTreeNode[] { new BspTreeNode(), new BspTreeNode() };
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var lTris = new List<TriangleRef>();
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var rTris = new List<TriangleRef>();
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foreach (var tri in tris)
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{
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var val = SplitLine.GetSplitResult(in splitLine, tri);
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if (val == EnumSplitType.Left)
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{ // 三角形位于切割线左侧，加入左子树三角形列表
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lTris.Add(tri);
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}
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else if (val == EnumSplitType.Right)
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{ // 三角形位于切割线右侧，加入右子树三角形列表
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rTris.Add(tri);
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}
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else
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{ // 切割线经过三角形，将三角形分为几个多边形
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SplitTriangle(lTris, rTris, tri);
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}
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}
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LeftChild.Init(lTris, depth + 1);
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RightChild.Init(rTris, depth + 1);
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}
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private readonly List<LVector2> m_RightVerts = new List<LVector2>();
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private readonly List<LVector2> m_LeftVerts = new List<LVector2>();
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/// <summary>
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/// 将三角形按切割线切割为若干个三角形
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/// </summary>
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/// <param name="lTris"></param>
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/// <param name="rTris"></param>
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/// <param name="tri"></param>
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private void SplitTriangle(List<TriangleRef> lTris, List<TriangleRef> rTris, TriangleRef tri)
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{
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int numVerts = 3;
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m_RightVerts.Clear();
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m_LeftVerts.Clear();
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var a = tri[2];
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var aSide = SplitLine.ClassifyPointToPlane(splitLine, a);
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for (int i = 0; i < numVerts; i++)
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{
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var b = tri[i];
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var bSide = SplitLine.ClassifyPointToPlane(splitLine, b);
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if (bSide == EnumSplitType.Right)
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{
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if (aSide == EnumSplitType.Left)
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{
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var p = SplitLine.GetIntersectPoint(a, b, splitLine.vertexA, splitLine.vertexB);
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m_RightVerts.Add(p);
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m_LeftVerts.Add(p);
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}
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else if (aSide == EnumSplitType.OnPlane)
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{
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if (m_RightVerts.Count == 0 || a != m_RightVerts[m_RightVerts.Count - 1])
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{
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m_RightVerts.Add(a);
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}
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}
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m_RightVerts.Add(b);
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}
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else if (bSide == EnumSplitType.Left)
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{
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if (aSide == EnumSplitType.Right)
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{
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var p = SplitLine.GetIntersectPoint(a, b, splitLine.vertexA, splitLine.vertexB);
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m_RightVerts.Add(p);
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m_LeftVerts.Add(p);
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}
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else if (aSide == EnumSplitType.OnPlane)
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{
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if (m_LeftVerts.Count == 0 || a != m_LeftVerts[m_LeftVerts.Count - 1])
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{
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m_LeftVerts.Add(a);
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}
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}
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m_LeftVerts.Add(b);
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}
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else
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{
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if (aSide == EnumSplitType.Right)
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{
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if (!(m_RightVerts.Count == 3 && b == m_RightVerts[0]))
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{
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m_RightVerts.Add(b);
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}
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}
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else if (aSide == EnumSplitType.Left)
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{
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if (!(m_LeftVerts.Count == 3 && b == m_LeftVerts[0]))
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{
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m_LeftVerts.Add(b);
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}
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}
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}
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a = b;
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aSide = bSide;
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}
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//push into tri list
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if (m_LeftVerts.Count >= 3)
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{
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if (m_LeftVerts.Count == 3)
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{
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AddTriangle(lTris, m_LeftVerts[0], m_LeftVerts[1], m_LeftVerts[2], tri);
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}
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else
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{
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// Debug.Assert(m_LeftVerts.Count == 4);
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AddTriangle(lTris, m_LeftVerts[0], m_LeftVerts[1], m_LeftVerts[2], tri);
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AddTriangle(lTris, m_LeftVerts[0], m_LeftVerts[2], m_LeftVerts[3], tri);
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}
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}
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if (m_RightVerts.Count >= 3)
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{
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if (m_RightVerts.Count == 3)
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{
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AddTriangle(rTris, m_RightVerts[0], m_RightVerts[1], m_RightVerts[2], tri);
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}
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else
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{
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// Debug.Assert(m_RightVerts.Count == 4);
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AddTriangle(rTris, m_RightVerts[0], m_RightVerts[1], m_RightVerts[2], tri);
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AddTriangle(rTris, m_RightVerts[0], m_RightVerts[2], m_RightVerts[3], tri);
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}
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}
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}
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private void AddTriangle(List<TriangleRef> triangles, in LVector2 vertexA, in LVector2 vertexB, in LVector2 vertexC, TriangleRef tri)
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{
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if (vertexA == vertexB || vertexB == vertexC || vertexC == vertexA) { return; }
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triangles.Add(new TriangleRef(vertexA, vertexB, vertexC, tri));
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}
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/// <summary>
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/// 选择一条合适的切割线
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/// </summary>
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/// <param name="tris">待切割的三角形集合</param>
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/// <returns></returns>
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private static SplitLine PickSplitLine(List<TriangleRef> tris)
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{
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int minScore = int.MinValue;
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int minLCount = 0;
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int minRCount = 0;
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SplitLine bestLine = new SplitLine();
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int[] splitCounter = new int[(int)EnumSplitType.EnumCount]; // 每次切割，三角形位于切割线左右和线上的次数统计
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var tirCount = tris.Count;
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foreach (var tri in tris)
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{ // 遍历所有三角形的边框线，作为切割线来切割空间，计算每次切割的分数，从而选取最优的分割线
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foreach (var borderLine in tri.borders)
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{
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for (int i = 0; i < (int)EnumSplitType.EnumCount; i++)
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{
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splitCounter[i] = 0;
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}
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foreach (var otherTri in tris)
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{
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var val = (int)SplitLine.GetSplitResult(borderLine, otherTri);
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splitCounter[val]++;
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}
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// Clock wise =>Left ++ CCW=>Right++// self tri is on the left
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var leftCount = splitCounter[(int)EnumSplitType.Left];
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var rightCount = splitCounter[(int)EnumSplitType.Right];
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var splitCount = splitCounter[(int)EnumSplitType.OnPlane];
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if ((leftCount == 0 || rightCount == 0) && (leftCount + rightCount) == tirCount)
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{
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// 所有的三角形都在同一侧，忽略
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continue;
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}
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// 根据切割线左右的三角形数，以及切割的三角形数，计算本次分割的得分
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var balanceVal = LMath.Abs(leftCount - rightCount);
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var sameVal = LMath.Min(leftCount, rightCount);
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int score = sameVal * 3 - balanceVal - splitCount * 2;
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if (score > minScore)
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{ // 选取得分最高的作为切割线
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minLCount = leftCount;
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minRCount = rightCount;
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minScore = score;
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bestLine = borderLine;
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}
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}
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}
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return bestLine;
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}
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}
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} |