btShapeHull.cpp

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00001 /*
00002 Bullet Continuous Collision Detection and Physics Library
00003 Copyright (c) 2003-2009 Erwin Coumans  http://bulletphysics.org
00004 
00005 This software is provided 'as-is', without any express or implied warranty.
00006 In no event will the authors be held liable for any damages arising from the use of this software.
00007 Permission is granted to anyone to use this software for any purpose, 
00008 including commercial applications, and to alter it and redistribute it freely, 
00009 subject to the following restrictions:
00010 
00011 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.
00012 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
00013 3. This notice may not be removed or altered from any source distribution.
00014 */
00015 
00016 //btShapeHull was implemented by John McCutchan.
00017 
00018 
00019 #include "btShapeHull.h"
00020 #include "LinearMath/btConvexHull.h"
00021 
00022 #define NUM_UNITSPHERE_POINTS 42
00023 
00024 btShapeHull::btShapeHull (const btConvexShape* shape)
00025 {
00026         m_shape = shape;
00027         m_vertices.clear ();
00028         m_indices.clear();
00029         m_numIndices = 0;
00030 }
00031 
00032 btShapeHull::~btShapeHull ()
00033 {
00034         m_indices.clear();      
00035         m_vertices.clear ();
00036 }
00037 
00038 bool
00039 btShapeHull::buildHull (btScalar /*margin*/)
00040 {
00041         int numSampleDirections = NUM_UNITSPHERE_POINTS;
00042         {
00043                 int numPDA = m_shape->getNumPreferredPenetrationDirections();
00044                 if (numPDA)
00045                 {
00046                         for (int i=0;i<numPDA;i++)
00047                         {
00048                                 btVector3 norm;
00049                                 m_shape->getPreferredPenetrationDirection(i,norm);
00050                                 getUnitSpherePoints()[numSampleDirections] = norm;
00051                                 numSampleDirections++;
00052                         }
00053                 }
00054         }
00055 
00056         btVector3 supportPoints[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2];
00057         int i;
00058         for (i = 0; i < numSampleDirections; i++)
00059         {
00060                 supportPoints[i] = m_shape->localGetSupportingVertex(getUnitSpherePoints()[i]);
00061         }
00062 
00063         HullDesc hd;
00064         hd.mFlags = QF_TRIANGLES;
00065         hd.mVcount = static_cast<unsigned int>(numSampleDirections);
00066 
00067 #ifdef BT_USE_DOUBLE_PRECISION
00068         hd.mVertices = &supportPoints[0];
00069         hd.mVertexStride = sizeof(btVector3);
00070 #else
00071         hd.mVertices = &supportPoints[0];
00072         hd.mVertexStride = sizeof (btVector3);
00073 #endif
00074 
00075         HullLibrary hl;
00076         HullResult hr;
00077         if (hl.CreateConvexHull (hd, hr) == QE_FAIL)
00078         {
00079                 return false;
00080         }
00081 
00082         m_vertices.resize (static_cast<int>(hr.mNumOutputVertices));
00083 
00084 
00085         for (i = 0; i < static_cast<int>(hr.mNumOutputVertices); i++)
00086         {
00087                 m_vertices[i] = hr.m_OutputVertices[i];
00088         }
00089         m_numIndices = hr.mNumIndices;
00090         m_indices.resize(static_cast<int>(m_numIndices));
00091         for (i = 0; i < static_cast<int>(m_numIndices); i++)
00092         {
00093                 m_indices[i] = hr.m_Indices[i];
00094         }
00095 
00096         // free temporary hull result that we just copied
00097         hl.ReleaseResult (hr);
00098 
00099         return true;
00100 }
00101 
00102 int
00103 btShapeHull::numTriangles () const
00104 {
00105         return static_cast<int>(m_numIndices / 3);
00106 }
00107 
00108 int
00109 btShapeHull::numVertices () const
00110 {
00111         return m_vertices.size ();
00112 }
00113 
00114 int
00115 btShapeHull::numIndices () const
00116 {
00117         return static_cast<int>(m_numIndices);
00118 }
00119 
00120 
00121 btVector3* btShapeHull::getUnitSpherePoints()
00122 {
00123         static btVector3 sUnitSpherePoints[NUM_UNITSPHERE_POINTS+MAX_PREFERRED_PENETRATION_DIRECTIONS*2] = 
00124         {
00125                 btVector3(btScalar(0.000000) , btScalar(-0.000000),btScalar(-1.000000)),
00126                 btVector3(btScalar(0.723608) , btScalar(-0.525725),btScalar(-0.447219)),
00127                 btVector3(btScalar(-0.276388) , btScalar(-0.850649),btScalar(-0.447219)),
00128                 btVector3(btScalar(-0.894426) , btScalar(-0.000000),btScalar(-0.447216)),
00129                 btVector3(btScalar(-0.276388) , btScalar(0.850649),btScalar(-0.447220)),
00130                 btVector3(btScalar(0.723608) , btScalar(0.525725),btScalar(-0.447219)),
00131                 btVector3(btScalar(0.276388) , btScalar(-0.850649),btScalar(0.447220)),
00132                 btVector3(btScalar(-0.723608) , btScalar(-0.525725),btScalar(0.447219)),
00133                 btVector3(btScalar(-0.723608) , btScalar(0.525725),btScalar(0.447219)),
00134                 btVector3(btScalar(0.276388) , btScalar(0.850649),btScalar(0.447219)),
00135                 btVector3(btScalar(0.894426) , btScalar(0.000000),btScalar(0.447216)),
00136                 btVector3(btScalar(-0.000000) , btScalar(0.000000),btScalar(1.000000)),
00137                 btVector3(btScalar(0.425323) , btScalar(-0.309011),btScalar(-0.850654)),
00138                 btVector3(btScalar(-0.162456) , btScalar(-0.499995),btScalar(-0.850654)),
00139                 btVector3(btScalar(0.262869) , btScalar(-0.809012),btScalar(-0.525738)),
00140                 btVector3(btScalar(0.425323) , btScalar(0.309011),btScalar(-0.850654)),
00141                 btVector3(btScalar(0.850648) , btScalar(-0.000000),btScalar(-0.525736)),
00142                 btVector3(btScalar(-0.525730) , btScalar(-0.000000),btScalar(-0.850652)),
00143                 btVector3(btScalar(-0.688190) , btScalar(-0.499997),btScalar(-0.525736)),
00144                 btVector3(btScalar(-0.162456) , btScalar(0.499995),btScalar(-0.850654)),
00145                 btVector3(btScalar(-0.688190) , btScalar(0.499997),btScalar(-0.525736)),
00146                 btVector3(btScalar(0.262869) , btScalar(0.809012),btScalar(-0.525738)),
00147                 btVector3(btScalar(0.951058) , btScalar(0.309013),btScalar(0.000000)),
00148                 btVector3(btScalar(0.951058) , btScalar(-0.309013),btScalar(0.000000)),
00149                 btVector3(btScalar(0.587786) , btScalar(-0.809017),btScalar(0.000000)),
00150                 btVector3(btScalar(0.000000) , btScalar(-1.000000),btScalar(0.000000)),
00151                 btVector3(btScalar(-0.587786) , btScalar(-0.809017),btScalar(0.000000)),
00152                 btVector3(btScalar(-0.951058) , btScalar(-0.309013),btScalar(-0.000000)),
00153                 btVector3(btScalar(-0.951058) , btScalar(0.309013),btScalar(-0.000000)),
00154                 btVector3(btScalar(-0.587786) , btScalar(0.809017),btScalar(-0.000000)),
00155                 btVector3(btScalar(-0.000000) , btScalar(1.000000),btScalar(-0.000000)),
00156                 btVector3(btScalar(0.587786) , btScalar(0.809017),btScalar(-0.000000)),
00157                 btVector3(btScalar(0.688190) , btScalar(-0.499997),btScalar(0.525736)),
00158                 btVector3(btScalar(-0.262869) , btScalar(-0.809012),btScalar(0.525738)),
00159                 btVector3(btScalar(-0.850648) , btScalar(0.000000),btScalar(0.525736)),
00160                 btVector3(btScalar(-0.262869) , btScalar(0.809012),btScalar(0.525738)),
00161                 btVector3(btScalar(0.688190) , btScalar(0.499997),btScalar(0.525736)),
00162                 btVector3(btScalar(0.525730) , btScalar(0.000000),btScalar(0.850652)),
00163                 btVector3(btScalar(0.162456) , btScalar(-0.499995),btScalar(0.850654)),
00164                 btVector3(btScalar(-0.425323) , btScalar(-0.309011),btScalar(0.850654)),
00165                 btVector3(btScalar(-0.425323) , btScalar(0.309011),btScalar(0.850654)),
00166                 btVector3(btScalar(0.162456) , btScalar(0.499995),btScalar(0.850654))
00167         };
00168         return sUnitSpherePoints;
00169 }
00170