1 /* 2 Copyright (c) 2011 Ole Kniemeyer, MAXON, www.maxon.net 3 4 This software is provided 'as-is', without any express or implied warranty. 5 In no event will the authors be held liable for any damages arising from the use of this software. 6 Permission is granted to anyone to use this software for any purpose, 7 including commercial applications, and to alter it and redistribute it freely, 8 subject to the following restrictions: 9 10 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. 11 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 12 3. This notice may not be removed or altered from any source distribution. 13 */ 14 15 #ifndef BT_CONVEX_HULL_COMPUTER_H 16 #define BT_CONVEX_HULL_COMPUTER_H 17 18 #include "btVector3.h" 19 #include "btAlignedObjectArray.h" 20 21 /// Convex hull implementation based on Preparata and Hong 22 /// See http://code.google.com/p/bullet/issues/detail?id=275 23 /// Ole Kniemeyer, MAXON Computer GmbH 24 class btConvexHullComputer 25 { 26 private: 27 btScalar compute(const void* coords, bool doubleCoords, int stride, int count, btScalar shrink, btScalar shrinkClamp); 28 29 public: 30 31 class Edge 32 { 33 private: 34 int next; 35 int reverse; 36 int targetVertex; 37 38 friend class btConvexHullComputer; 39 40 public: getSourceVertex()41 int getSourceVertex() const 42 { 43 return (this + reverse)->targetVertex; 44 } 45 getTargetVertex()46 int getTargetVertex() const 47 { 48 return targetVertex; 49 } 50 getNextEdgeOfVertex()51 const Edge* getNextEdgeOfVertex() const // clockwise list of all edges of a vertex 52 { 53 return this + next; 54 } 55 getNextEdgeOfFace()56 const Edge* getNextEdgeOfFace() const // counter-clockwise list of all edges of a face 57 { 58 return (this + reverse)->getNextEdgeOfVertex(); 59 } 60 getReverseEdge()61 const Edge* getReverseEdge() const 62 { 63 return this + reverse; 64 } 65 }; 66 67 68 // Vertices of the output hull 69 btAlignedObjectArray<btVector3> vertices; 70 71 // Edges of the output hull 72 btAlignedObjectArray<Edge> edges; 73 74 // Faces of the convex hull. Each entry is an index into the "edges" array pointing to an edge of the face. Faces are planar n-gons 75 btAlignedObjectArray<int> faces; 76 77 /* 78 Compute convex hull of "count" vertices stored in "coords". "stride" is the difference in bytes 79 between the addresses of consecutive vertices. If "shrink" is positive, the convex hull is shrunken 80 by that amount (each face is moved by "shrink" length units towards the center along its normal). 81 If "shrinkClamp" is positive, "shrink" is clamped to not exceed "shrinkClamp * innerRadius", where "innerRadius" 82 is the minimum distance of a face to the center of the convex hull. 83 84 The returned value is the amount by which the hull has been shrunken. If it is negative, the amount was so large 85 that the resulting convex hull is empty. 86 87 The output convex hull can be found in the member variables "vertices", "edges", "faces". 88 */ compute(const float * coords,int stride,int count,btScalar shrink,btScalar shrinkClamp)89 btScalar compute(const float* coords, int stride, int count, btScalar shrink, btScalar shrinkClamp) 90 { 91 return compute(coords, false, stride, count, shrink, shrinkClamp); 92 } 93 94 // same as above, but double precision compute(const double * coords,int stride,int count,btScalar shrink,btScalar shrinkClamp)95 btScalar compute(const double* coords, int stride, int count, btScalar shrink, btScalar shrinkClamp) 96 { 97 return compute(coords, true, stride, count, shrink, shrinkClamp); 98 } 99 }; 100 101 102 #endif //BT_CONVEX_HULL_COMPUTER_H 103 104