1 2 /* 3 Stan Melax Convex Hull Computation 4 Copyright (c) 2008 Stan Melax http://www.melax.com/ 5 6 This software is provided 'as-is', without any express or implied warranty. 7 In no event will the authors be held liable for any damages arising from the use of this software. 8 Permission is granted to anyone to use this software for any purpose, 9 including commercial applications, and to alter it and redistribute it freely, 10 subject to the following restrictions: 11 12 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 13 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 14 3. This notice may not be removed or altered from any source distribution. 15 */ 16 17 ///includes modifications/improvements by John Ratcliff, see BringOutYourDead below. 18 19 #ifndef BT_CD_HULL_H 20 #define BT_CD_HULL_H 21 22 #include "btVector3.h" 23 #include "btAlignedObjectArray.h" 24 25 typedef btAlignedObjectArray<unsigned int> TUIntArray; 26 27 class HullResult 28 { 29 public: 30 HullResult(void) 31 { 32 mPolygons = true; 33 mNumOutputVertices = 0; 34 mNumFaces = 0; 35 mNumIndices = 0; 36 } 37 bool mPolygons; // true if indices represents polygons, false indices are triangles 38 unsigned int mNumOutputVertices; // number of vertices in the output hull 39 btAlignedObjectArray<btVector3> m_OutputVertices; // array of vertices 40 unsigned int mNumFaces; // the number of faces produced 41 unsigned int mNumIndices; // the total number of indices 42 btAlignedObjectArray<unsigned int> m_Indices; // pointer to indices. 43 44 // If triangles, then indices are array indexes into the vertex list. 45 // If polygons, indices are in the form (number of points in face) (p1, p2, p3, ..) etc.. 46 }; 47 48 enum HullFlag 49 { 50 QF_TRIANGLES = (1<<0), // report results as triangles, not polygons. 51 QF_REVERSE_ORDER = (1<<1), // reverse order of the triangle indices. 52 QF_DEFAULT = QF_TRIANGLES 53 }; 54 55 56 class HullDesc 57 { 58 public: 59 HullDesc(void) 60 { 61 mFlags = QF_DEFAULT; 62 mVcount = 0; 63 mVertices = 0; 64 mVertexStride = sizeof(btVector3); 65 mNormalEpsilon = 0.001f; 66 mMaxVertices = 4096; // maximum number of points to be considered for a convex hull. 67 mMaxFaces = 4096; 68 }; 69 70 HullDesc(HullFlag flag, 71 unsigned int vcount, 72 const btVector3 *vertices, 73 unsigned int stride = sizeof(btVector3)) 74 { 75 mFlags = flag; 76 mVcount = vcount; 77 mVertices = vertices; 78 mVertexStride = stride; 79 mNormalEpsilon = btScalar(0.001); 80 mMaxVertices = 4096; 81 } 82 83 bool HasHullFlag(HullFlag flag) const 84 { 85 if ( mFlags & flag ) return true; 86 return false; 87 } 88 89 void SetHullFlag(HullFlag flag) 90 { 91 mFlags|=flag; 92 } 93 94 void ClearHullFlag(HullFlag flag) 95 { 96 mFlags&=~flag; 97 } 98 99 unsigned int mFlags; // flags to use when generating the convex hull. 100 unsigned int mVcount; // number of vertices in the input point cloud 101 const btVector3 *mVertices; // the array of vertices. 102 unsigned int mVertexStride; // the stride of each vertex, in bytes. 103 btScalar mNormalEpsilon; // the epsilon for removing duplicates. This is a normalized value, if normalized bit is on. 104 unsigned int mMaxVertices; // maximum number of vertices to be considered for the hull! 105 unsigned int mMaxFaces; 106 }; 107 108 enum HullError 109 { 110 QE_OK, // success! 111 QE_FAIL // failed. 112 }; 113 114 class btPlane 115 { 116 public: 117 btVector3 normal; 118 btScalar dist; // distance below origin - the D from plane equasion Ax+By+Cz+D=0 119 btPlane(const btVector3 &n,btScalar d):normal(n),dist(d){} 120 btPlane():normal(),dist(0){} 121 122 }; 123 124 125 126 class ConvexH 127 { 128 public: 129 class HalfEdge 130 { 131 public: 132 short ea; // the other half of the edge (index into edges list) 133 unsigned char v; // the vertex at the start of this edge (index into vertices list) 134 unsigned char p; // the facet on which this edge lies (index into facets list) 135 HalfEdge(){} 136 HalfEdge(short _ea,unsigned char _v, unsigned char _p):ea(_ea),v(_v),p(_p){} 137 }; 138 ConvexH() 139 { 140 } 141 ~ConvexH() 142 { 143 } 144 btAlignedObjectArray<btVector3> vertices; 145 btAlignedObjectArray<HalfEdge> edges; 146 btAlignedObjectArray<btPlane> facets; 147 ConvexH(int vertices_size,int edges_size,int facets_size); 148 }; 149 150 151 class int4 152 { 153 public: 154 int x,y,z,w; 155 int4(){}; 156 int4(int _x,int _y, int _z,int _w){x=_x;y=_y;z=_z;w=_w;} 157 const int& operator[](int i) const {return (&x)[i];} 158 int& operator[](int i) {return (&x)[i];} 159 }; 160 161 class PHullResult 162 { 163 public: 164 165 PHullResult(void) 166 { 167 mVcount = 0; 168 mIndexCount = 0; 169 mFaceCount = 0; 170 mVertices = 0; 171 } 172 173 unsigned int mVcount; 174 unsigned int mIndexCount; 175 unsigned int mFaceCount; 176 btVector3* mVertices; 177 TUIntArray m_Indices; 178 }; 179 180 181 182 ///The HullLibrary class can create a convex hull from a collection of vertices, using the ComputeHull method. 183 ///The btShapeHull class uses this HullLibrary to create a approximate convex mesh given a general (non-polyhedral) convex shape. 184 class HullLibrary 185 { 186 187 btAlignedObjectArray<class btHullTriangle*> m_tris; 188 189 public: 190 191 btAlignedObjectArray<int> m_vertexIndexMapping; 192 193 194 HullError CreateConvexHull(const HullDesc& desc, // describes the input request 195 HullResult& result); // contains the resulst 196 HullError ReleaseResult(HullResult &result); // release memory allocated for this result, we are done with it. 197 198 private: 199 200 bool ComputeHull(unsigned int vcount,const btVector3 *vertices,PHullResult &result,unsigned int vlimit); 201 202 class btHullTriangle* allocateTriangle(int a,int b,int c); 203 void deAllocateTriangle(btHullTriangle*); 204 void b2bfix(btHullTriangle* s,btHullTriangle*t); 205 206 void removeb2b(btHullTriangle* s,btHullTriangle*t); 207 208 void checkit(btHullTriangle *t); 209 210 btHullTriangle* extrudable(btScalar epsilon); 211 212 int calchull(btVector3 *verts,int verts_count, TUIntArray& tris_out, int &tris_count,int vlimit); 213 214 int calchullgen(btVector3 *verts,int verts_count, int vlimit); 215 216 int4 FindSimplex(btVector3 *verts,int verts_count,btAlignedObjectArray<int> &allow); 217 218 class ConvexH* ConvexHCrop(ConvexH& convex,const btPlane& slice); 219 220 void extrude(class btHullTriangle* t0,int v); 221 222 ConvexH* test_cube(); 223 224 //BringOutYourDead (John Ratcliff): When you create a convex hull you hand it a large input set of vertices forming a 'point cloud'. 225 //After the hull is generated it give you back a set of polygon faces which index the *original* point cloud. 226 //The thing is, often times, there are many 'dead vertices' in the point cloud that are on longer referenced by the hull. 227 //The routine 'BringOutYourDead' find only the referenced vertices, copies them to an new buffer, and re-indexes the hull so that it is a minimal representation. 228 void BringOutYourDead(const btVector3* verts,unsigned int vcount, btVector3* overts,unsigned int &ocount,unsigned int* indices,unsigned indexcount); 229 230 bool CleanupVertices(unsigned int svcount, 231 const btVector3* svertices, 232 unsigned int stride, 233 unsigned int &vcount, // output number of vertices 234 btVector3* vertices, // location to store the results. 235 btScalar normalepsilon, 236 btVector3& scale); 237 }; 238 239 240 #endif //BT_CD_HULL_H 241 242
