316 lines
7.3 KiB
C++
316 lines
7.3 KiB
C++
//
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// Copyright (c) 2009-2010 Mikko Mononen memon@inside.org
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//
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// This software is provided 'as-is', without any express or implied
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// warranty. In no event will the authors be held liable for any damages
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// arising from the use of this software.
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// Permission is granted to anyone to use this software for any purpose,
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// including commercial applications, and to alter it and redistribute it
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// freely, subject to the following restrictions:
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// 1. The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software. If you use this software
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// in a product, an acknowledgment in the product documentation would be
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// appreciated but is not required.
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// 2. Altered source versions must be plainly marked as such, and must not be
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// misrepresented as being the original software.
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// 3. This notice may not be removed or altered from any source distribution.
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//
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#include "ChunkyTriMesh.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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struct BoundsItem
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{
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float bmin[2];
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float bmax[2];
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int i;
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};
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static int compareItemX(const void* va, const void* vb)
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{
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const BoundsItem* a = (const BoundsItem*)va;
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const BoundsItem* b = (const BoundsItem*)vb;
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if (a->bmin[0] < b->bmin[0])
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return -1;
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if (a->bmin[0] > b->bmin[0])
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return 1;
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return 0;
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}
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static int compareItemY(const void* va, const void* vb)
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{
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const BoundsItem* a = (const BoundsItem*)va;
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const BoundsItem* b = (const BoundsItem*)vb;
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if (a->bmin[1] < b->bmin[1])
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return -1;
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if (a->bmin[1] > b->bmin[1])
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return 1;
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return 0;
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}
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static void calcExtends(const BoundsItem* items, const int /*nitems*/,
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const int imin, const int imax,
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float* bmin, float* bmax)
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{
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bmin[0] = items[imin].bmin[0];
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bmin[1] = items[imin].bmin[1];
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bmax[0] = items[imin].bmax[0];
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bmax[1] = items[imin].bmax[1];
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for (int i = imin+1; i < imax; ++i)
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{
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const BoundsItem& it = items[i];
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if (it.bmin[0] < bmin[0]) bmin[0] = it.bmin[0];
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if (it.bmin[1] < bmin[1]) bmin[1] = it.bmin[1];
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if (it.bmax[0] > bmax[0]) bmax[0] = it.bmax[0];
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if (it.bmax[1] > bmax[1]) bmax[1] = it.bmax[1];
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}
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}
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inline int longestAxis(float x, float y)
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{
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return y > x ? 1 : 0;
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}
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static void subdivide(BoundsItem* items, int nitems, int imin, int imax, int trisPerChunk,
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int& curNode, rcChunkyTriMeshNode* nodes, const int maxNodes,
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int& curTri, int* outTris, const int* inTris)
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{
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int inum = imax - imin;
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int icur = curNode;
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if (curNode >= maxNodes)
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return;
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rcChunkyTriMeshNode& node = nodes[curNode++];
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if (inum <= trisPerChunk)
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{
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// Leaf
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calcExtends(items, nitems, imin, imax, node.bmin, node.bmax);
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// Copy triangles.
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node.i = curTri;
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node.n = inum;
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for (int i = imin; i < imax; ++i)
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{
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const int* src = &inTris[items[i].i*3];
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int* dst = &outTris[curTri*3];
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curTri++;
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dst[0] = src[0];
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dst[1] = src[1];
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dst[2] = src[2];
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}
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}
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else
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{
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// Split
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calcExtends(items, nitems, imin, imax, node.bmin, node.bmax);
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int axis = longestAxis(node.bmax[0] - node.bmin[0],
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node.bmax[1] - node.bmin[1]);
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if (axis == 0)
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{
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// Sort along x-axis
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qsort(items+imin, static_cast<size_t>(inum), sizeof(BoundsItem), compareItemX);
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}
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else if (axis == 1)
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{
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// Sort along y-axis
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qsort(items+imin, static_cast<size_t>(inum), sizeof(BoundsItem), compareItemY);
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}
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int isplit = imin+inum/2;
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// Left
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subdivide(items, nitems, imin, isplit, trisPerChunk, curNode, nodes, maxNodes, curTri, outTris, inTris);
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// Right
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subdivide(items, nitems, isplit, imax, trisPerChunk, curNode, nodes, maxNodes, curTri, outTris, inTris);
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int iescape = curNode - icur;
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// Negative index means escape.
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node.i = -iescape;
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}
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}
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bool rcCreateChunkyTriMesh(const float* verts, const int* tris, int ntris,
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int trisPerChunk, rcChunkyTriMesh* cm)
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{
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int nchunks = (ntris + trisPerChunk-1) / trisPerChunk;
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cm->nodes = new rcChunkyTriMeshNode[nchunks*4];
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if (!cm->nodes)
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return false;
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cm->tris = new int[ntris*3];
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if (!cm->tris)
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return false;
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cm->ntris = ntris;
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// Build tree
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BoundsItem* items = new BoundsItem[ntris];
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if (!items)
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return false;
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for (int i = 0; i < ntris; i++)
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{
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const int* t = &tris[i*3];
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BoundsItem& it = items[i];
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it.i = i;
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// Calc triangle XZ bounds.
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it.bmin[0] = it.bmax[0] = verts[t[0]*3+0];
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it.bmin[1] = it.bmax[1] = verts[t[0]*3+2];
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for (int j = 1; j < 3; ++j)
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{
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const float* v = &verts[t[j]*3];
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if (v[0] < it.bmin[0]) it.bmin[0] = v[0];
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if (v[2] < it.bmin[1]) it.bmin[1] = v[2];
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if (v[0] > it.bmax[0]) it.bmax[0] = v[0];
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if (v[2] > it.bmax[1]) it.bmax[1] = v[2];
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}
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}
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int curTri = 0;
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int curNode = 0;
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subdivide(items, ntris, 0, ntris, trisPerChunk, curNode, cm->nodes, nchunks*4, curTri, cm->tris, tris);
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delete [] items;
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cm->nnodes = curNode;
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// Calc max tris per node.
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cm->maxTrisPerChunk = 0;
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for (int i = 0; i < cm->nnodes; ++i)
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{
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rcChunkyTriMeshNode& node = cm->nodes[i];
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const bool isLeaf = node.i >= 0;
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if (!isLeaf) continue;
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if (node.n > cm->maxTrisPerChunk)
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cm->maxTrisPerChunk = node.n;
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}
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return true;
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}
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inline bool checkOverlapRect(const float amin[2], const float amax[2],
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const float bmin[2], const float bmax[2])
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{
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bool overlap = true;
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overlap = (amin[0] > bmax[0] || amax[0] < bmin[0]) ? false : overlap;
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overlap = (amin[1] > bmax[1] || amax[1] < bmin[1]) ? false : overlap;
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return overlap;
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}
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int rcGetChunksOverlappingRect(const rcChunkyTriMesh* cm,
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float bmin[2], float bmax[2],
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int* ids, const int maxIds)
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{
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// Traverse tree
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int i = 0;
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int n = 0;
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while (i < cm->nnodes)
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{
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const rcChunkyTriMeshNode* node = &cm->nodes[i];
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const bool overlap = checkOverlapRect(bmin, bmax, node->bmin, node->bmax);
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const bool isLeafNode = node->i >= 0;
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if (isLeafNode && overlap)
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{
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if (n < maxIds)
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{
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ids[n] = i;
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n++;
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}
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}
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if (overlap || isLeafNode)
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i++;
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else
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{
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const int escapeIndex = -node->i;
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i += escapeIndex;
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}
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}
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return n;
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}
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static bool checkOverlapSegment(const float p[2], const float q[2],
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const float bmin[2], const float bmax[2])
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{
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static const float EPSILON = 1e-6f;
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float tmin = 0;
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float tmax = 1;
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float d[2];
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d[0] = q[0] - p[0];
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d[1] = q[1] - p[1];
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for (int i = 0; i < 2; i++)
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{
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if (fabsf(d[i]) < EPSILON)
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{
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// Ray is parallel to slab. No hit if origin not within slab
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if (p[i] < bmin[i] || p[i] > bmax[i])
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return false;
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}
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else
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{
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// Compute intersection t value of ray with near and far plane of slab
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float ood = 1.0f / d[i];
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float t1 = (bmin[i] - p[i]) * ood;
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float t2 = (bmax[i] - p[i]) * ood;
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if (t1 > t2) { float tmp = t1; t1 = t2; t2 = tmp; }
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if (t1 > tmin) tmin = t1;
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if (t2 < tmax) tmax = t2;
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if (tmin > tmax) return false;
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}
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}
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return true;
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}
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int rcGetChunksOverlappingSegment(const rcChunkyTriMesh* cm,
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float p[2], float q[2],
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int* ids, const int maxIds)
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{
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// Traverse tree
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int i = 0;
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int n = 0;
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while (i < cm->nnodes)
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{
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const rcChunkyTriMeshNode* node = &cm->nodes[i];
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const bool overlap = checkOverlapSegment(p, q, node->bmin, node->bmax);
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const bool isLeafNode = node->i >= 0;
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if (isLeafNode && overlap)
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{
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if (n < maxIds)
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{
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ids[n] = i;
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n++;
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}
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}
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if (overlap || isLeafNode)
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i++;
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else
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{
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const int escapeIndex = -node->i;
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i += escapeIndex;
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}
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}
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return n;
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}
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