} // build
private static void buildAdjacencyData(PolyMeshField mesh)
{
int vertCount = mesh.verts.Length / 3;
int polyCount = mesh.polyRegions.Length;
int maxEdgeCount = polyCount * mesh.maxVertsPerPoly(); // 多边形的个数乘以顶点数？
int[] edges = new int[maxEdgeCount * 6];
int edgeCount = 0;
int[] startEdge = new int[vertCount];
for (int i = 0; i < startEdge.Length; ++i)
{
startEdge[i] = PolyMeshField.NULL_INDEX;
}
//数组链表
int[] nextEdge = new int[maxEdgeCount];
for (int iPoly = 0; iPoly < polyCount; ++iPoly)
{
int pPoly = iPoly * mesh.maxVertsPerPoly() * 2; //两组maxVertPerPoly为步长
for (int vertOffset = 0; vertOffset < mesh.maxVertsPerPoly(); ++vertOffset)
{
int iVert = mesh.polys[pPoly + vertOffset]; //第一组maxVertsPerPoly的数据
if (PolyMeshField.NULL_INDEX == iVert)
{
break;
}
//如果 maxVertsPerPoly = 6 ，那当vertOffset = 5 的时候会发生什么？
//那iNextVert就会回到起点
int iNextVert;
if (vertOffset + 1 >= mesh.maxVertsPerPoly() ||
mesh.polys[pPoly + vertOffset + 1] == PolyMeshField.NULL_INDEX)
{
iNextVert = mesh.polys[pPoly];
}
else
{
iNextVert = mesh.polys[pPoly + vertOffset + 1];
}
if (iVert < iNextVert)
{
int edgeBaseIdx = edgeCount * 6;
//一条边的两个端点
edges[edgeBaseIdx] = iVert;
edges[edgeBaseIdx + 1] = iNextVert;
//这条边在多边形里面的信息
edges[edgeBaseIdx + 2] = iPoly;
edges[edgeBaseIdx + 3] = vertOffset;
//默认是边界边
edges[edgeBaseIdx + 4] = PolyMeshField.NULL_INDEX;
edges[edgeBaseIdx + 5] = PolyMeshField.NULL_INDEX;
//倒插链表？ iVert顶点 -> edgeCount 边 -> 然后edgeCount 就是链表尾了
//TODO 源码这里也是这样，不知道为毛
nextEdge[edgeCount] = startEdge[iVert]; //???这个东西不是NULL_INDEX么？
startEdge[iVert] = edgeCount;
edgeCount++;
}
} // for vertOffset
} // for Poly
for (int iPoly = 0; iPoly < polyCount; ++iPoly)
{
int pPoly = iPoly * mesh.maxVertsPerPoly() * 2;
for (int vertOffset = 0; vertOffset < mesh.maxVertsPerPoly(); ++vertOffset)
{
int iVert = mesh.polys[pPoly + vertOffset];
if (PolyMeshField.NULL_INDEX == iVert)
{
break;
}
int iNextVert;
if (vertOffset + 1 >= mesh.maxVertsPerPoly() ||
mesh.polys[pPoly + vertOffset] == PolyMeshField.NULL_INDEX)
{
iNextVert = mesh.polys[pPoly];
}
else
{
iNextVert = mesh.polys[pPoly + vertOffset];
}
//这里是反向查找共享边的信息
if (iVert > iNextVert)
{
for (int edgeIndex = startEdge[iNextVert]; edgeIndex != PolyMeshField.NULL_INDEX; edgeIndex = nextEdge[edgeIndex])
{
if (iVert == edges[edgeIndex * 6 + 1])
{
edges[edgeIndex * 6 + 4] = iPoly;
edges[edgeIndex * 6 + 5] = vertOffset;
break;
}
} // for
} //if ivert > iNextVert
} // for vertOffset
} // for Poly
for (int pEdge = 0; pEdge < edgeCount; pEdge += 6)
{
//是否共享边 ？
if (edges[pEdge + 4] != PolyMeshField.NULL_INDEX)
{
int pPolyA = edges[pEdge + 2] * mesh.maxVertsPerPoly() * 2;
int pPolyB = edges[pEdge + 4] * mesh.maxVertsPerPoly() * 2;
//参考 poly和edges数组的定义。描述的就是polyA的哪些边与哪个poly共享
mesh.polys[pPolyA + mesh.maxVertsPerPoly() + edges[pEdge + 3]] = edges[pEdge + 4];
mesh.polys[pPolyB + mesh.maxVertsPerPoly() + edges[pEdge + 5]] = edges[pEdge + 2];
}
}
}// func
public PolyMeshField build(ContourSet contours)
{
if (null == contours ||
0 == contours.size())
{
Logger.LogError("[PolyMeshFieldBuild][build]Param Error");
return(null);
}
PolyMeshField result = new PolyMeshField(contours.boundsMin(),
contours.boundsMax(),
contours.cellSize(),
contours.cellHeight(),
mMaxVertsPerPoly);
int sourceVertCount = 0;
int maxPossiblePolygons = 0;
int maxVertsPerContour = 0;
for (int contourIndex = 0; contourIndex < contours.size(); ++contourIndex)
{
int count = contours.get(contourIndex).vertCount;
sourceVertCount += count;
//过 n 边形的一个顶点，能把n边形最多分成 n - 2 三角形
maxPossiblePolygons += count - 2;
maxVertsPerContour = Math.Max(maxVertsPerContour, count);
}
if (sourceVertCount - 1 > DEFLAG)
{
Logger.LogError("[PolyMeshFieldBuilder][build]sourceVertCount out of Range|{0}|{1}", DEFLAG, sourceVertCount);
return(null);
}
int[] globalVerts = new int[sourceVertCount * 3]; //存的是索引，存的是整个轮廓的
int globalVertCount = 0;
int[] globalPolys = new int[maxPossiblePolygons * mMaxVertsPerPoly]; //存的也是索引
for (int i = 0; i < globalPolys.Length; ++i)
{
globalPolys[i] = PolyMeshField.NULL_INDEX;
}
int[] globalRegions = new int[maxPossiblePolygons];
int globalPolyCount = 0;
int[] contourToGlobalIndicesMap = new int[maxVertsPerContour]; //存的也是索引
Dictionary <int, int> vertIndices = new Dictionary <int, int>();
List <int> workingIndices = new List <int>(maxVertsPerContour);
List <int> workingTriangles = new List <int>(maxVertsPerContour);
//TODO 为什么要+1？
int[] workingPolys = new int[(maxVertsPerContour + 1) * mMaxVertsPerPoly];
int workingPolyCount = 0;
int[] mergeInfo = new int[3];
int[] mergedPoly = new int[mMaxVertsPerPoly];
for (int contourIndex = 0; contourIndex < contours.size(); ++contourIndex)
{
Contour contour = contours.get(contourIndex);
//4个数据一组，(x,y,z,regionID)，最少需要三个顶点
if (contour.verts.Length < 3 * 4)
{
Logger.LogError("[PolyMeshFieldBuilder][build]Bad Contour|{0}", contour.regionID);
continue;
}
//初始情况下，顶点索引对应的就是对应的顶点
/*
* Indices : 0 1 2 3 4 5 6 ....
* 0 1 2 3 4 5 6 ....
*/
workingIndices.Clear();
for (int i = 0; i < contour.vertCount; ++i) //这个顶点数是按四个一组的
{
workingIndices.Add(i);
} // for contour.vert
//三角剖分
int triangleCount = triangulate(contour.verts, ref workingIndices, ref workingTriangles);
if (triangleCount <= 0)
{
Logger.LogError("[PolyMeshField][build]Triangulate Contour|{0}", contour.regionID);
continue;
}
for (int iContourVert = 0; iContourVert < contour.vertCount; ++iContourVert)
{
int pContourVert = iContourVert * 4;
int vertHash = getHashCode(contour.verts[pContourVert],
contour.verts[pContourVert + 1],
contour.verts[pContourVert + 2]);
//vertIndices 里面储存的是根据顶点xyz hash出来的key，对应的在全局顶点表中的索引
//全局顶点表 以 xyz 3个为一组，储存轮廓的顶点
int iGlobalVert = 0;
if (!vertIndices.TryGetValue(vertHash, out iGlobalVert))
{
iGlobalVert = globalVertCount;
globalVertCount++;
vertIndices.Add(vertHash, iGlobalVert);
int newVertsBase = iGlobalVert * 3;
globalVerts[newVertsBase] = contour.verts[pContourVert];
globalVerts[newVertsBase + 1] = contour.verts[pContourVert + 1];
globalVerts[newVertsBase + 2] = contour.verts[pContourVert + 2];
}
//这个东东是临时用的，就是记录 轮廓中某个顶点的索引，对应的是在全局顶点表中索引
//Contour Vertex index -> global vertex index
contourToGlobalIndicesMap[iContourVert] = iGlobalVert;
} // for iContourVert
for (int i = 0; i < workingPolys.Length; ++i)
{
workingPolys[i] = PolyMeshField.NULL_INDEX;
} // for workingPolys
//只有这个阶段是三角形
workingPolyCount = 0;
for (int i = 0; i < triangleCount; ++i)
{
/*
* workingTraingles 储存的是上一步三角剖分的三角形的顶点索引
* ||
* V
* contourToGlobalIndicesMap 储存的是轮廓顶点索引，对应在全局顶点表的索引关系
* ||
* V
* workingPolys 中 储存的则是全局的顶点索引
*
*
*/
int polyIdxBase = workingPolyCount * mMaxVertsPerPoly;
int triangleIdxBase = i * 3;
workingPolys[polyIdxBase] =
contourToGlobalIndicesMap[workingTriangles[triangleIdxBase]];
workingPolys[polyIdxBase + 1] =
contourToGlobalIndicesMap[workingTriangles[triangleIdxBase + 1]];
workingPolys[polyIdxBase + 2] =
contourToGlobalIndicesMap[workingTriangles[triangleIdxBase] + 2];
workingPolyCount++;
} //triangleCount
//合并三角形
if (mMaxVertsPerPoly > 3)
{
while (true)
{
int longestMergeEdge = -1;
int pBestPolyA = -1;
int iPolyAVert = -1;
int pBestPolyB = -1;
int iPolyBVert = -1;
for (int iPolyA = 0; iPolyA < workingPolyCount - 1; ++iPolyA)
{
for (int iPolyB = iPolyA + 1; iPolyB < workingPolyCount; ++iPolyB)
{
//因为一个多边形最多有mMaxVertsPerPoly的点，所以
//多边形的真正起点为就是用多边形的索引乘以顶点数
//Can polyB merge with polyA?
getPolyMergeInfo(iPolyA * mMaxVertsPerPoly,
iPolyB * mMaxVertsPerPoly,
workingPolys,
globalVerts,
result.maxVertsPerPoly(),
out mergeInfo);
if (mergeInfo[0] > longestMergeEdge)
{
longestMergeEdge = mergeInfo[0];
pBestPolyA = iPolyA * mMaxVertsPerPoly;
iPolyAVert = mergeInfo[1];
pBestPolyB = iPolyB * mMaxVertsPerPoly;
iPolyBVert = mergeInfo[2];
}
} // for iPolyB
} // for iPolyA
if (longestMergeEdge <= 0)
{
break;
}
for (int i = 0; i < mergedPoly.Length; ++i)
{
mergedPoly[i] = PolyMeshField.NULL_INDEX;
}
int vertCountA = PolyMeshField.getPolyVertCount(pBestPolyA, workingPolys, result.maxVertsPerPoly());
int vertCountB = PolyMeshField.getPolyVertCount(pBestPolyB, workingPolys, result.maxVertsPerPoly());
int position = 0;
for (int i = 0; i < vertCountA - 1; ++i)
{
//pBestPolyA 为多边形对应的基索引
//iPolyAVert 为共享的一个端点
//+1 指的是共享点下一个顶点开始
int polyIdx = pBestPolyA + ((iPolyAVert + 1 + i) % vertCountA);
mergedPoly[position++] = workingPolys[polyIdx];
} // for vertCountA
for (int i = 0; i < vertCountB - 1; ++i)
{
int polyIdx = pBestPolyB + ((iPolyBVert + 1 + i) % vertCountB);
mergedPoly[position++] = workingPolys[polyIdx];
}
//将合并之后的顶点拷到A指定的多边形
Array.Copy(mergedPoly, 0, workingPolys, pBestPolyA, mMaxVertsPerPoly);
//将多边形B删除
Array.Copy(workingPolys, pBestPolyB + mMaxVertsPerPoly, workingPolys, pBestPolyB, workingPolys.Length - pBestPolyB - mMaxVertsPerPoly);
workingPolyCount--;
} // while true
} // if MaxVertsPerPoly
for (int i = 0; i < workingPolyCount; ++i)
{
Array.Copy(workingPolys, i * mMaxVertsPerPoly,
globalPolys, globalPolyCount * mMaxVertsPerPoly, mMaxVertsPerPoly);
globalRegions[globalPolyCount] = contour.regionID;
globalPolyCount++;
}
} // for contours
//xyz为一组
result.verts = new int[globalVertCount * 3];
Array.Copy(globalVerts, 0, result.verts, 0, globalVertCount * 3);
result.polys = new int[globalPolyCount * mMaxVertsPerPoly * 2];
for (int iPoly = 0; iPoly < globalPolyCount; ++iPoly)
{
int pPoly = iPoly * mMaxVertsPerPoly; //第几个Poly的索引
for (int offset = 0; offset < mMaxVertsPerPoly; ++offset)
{
//result里的多边形是以 2 * mMaxVertsPerPoly为一组的
//第一组 mMaxVertsPerPoly 是多边形自身的数据
//第二组 mMaxVertsPertPol 是邻接多边形的数据
//而globalPolys就是以一组 mMaxVertsPerPoly
result.polys[pPoly * 2 + offset] = globalPolys[pPoly + offset];
result.polys[pPoly * 2 + mMaxVertsPerPoly + offset] = PolyMeshField.NULL_INDEX;
}
} // for
result.polyRegions = new int[globalPolyCount];
Array.Copy(globalRegions, 0, result.polyRegions, 0, globalPolyCount);
buildAdjacencyData(result);
return(result);
} // build