[2912] | 1 | #include "Polyhedron.h"
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| 2 | #include "common.h"
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| 3 | #include "Polygon3.h"
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| 4 | #include "Plane3.h"
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| 5 |
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| 6 |
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| 7 | using namespace std;
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| 8 |
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| 9 |
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| 10 | namespace CHCDemoEngine
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| 11 | {
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| 12 |
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| 13 | static const float epsilon = 1e-6f;
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| 14 |
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[2929] | 15 |
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| 16 |
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[2931] | 17 | /************************************************************/
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| 18 | /* class Polyhedron Implementation */
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| 19 | /************************************************************/
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[2912] | 20 |
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| 21 |
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| 22 | Polyhedron::Polyhedron()
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| 23 | {
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| 24 | mBox.Initialize();
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| 25 | }
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| 26 |
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| 27 |
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| 28 | Polyhedron::Polyhedron(const PolygonContainer &polys)
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| 29 | {
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| 30 | mPolygons = polys;
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| 31 |
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| 32 | mBox.Initialize();
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| 33 | mBox.Include(mPolygons);
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| 34 | }
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| 35 |
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| 36 |
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| 37 | Polyhedron::Polyhedron(const Polyhedron &rhs)
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| 38 | {
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| 39 | mPolygons.reserve(rhs.mPolygons.size());
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| 40 | mBox = rhs.mBox;
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| 41 |
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| 42 | PolygonContainer::const_iterator it, it_end = rhs.mPolygons.end();
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| 43 |
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| 44 | for (it = rhs.mPolygons.begin(); it != it_end; ++ it)
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| 45 | Add(new Polygon3(*(*it)));
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| 46 | }
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| 47 |
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| 48 |
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[2929] | 49 | Polyhedron *Polyhedron::CreatePolyhedron(const vector<Plane3> &planes,
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| 50 | const AxisAlignedBox3 &sceneBox)
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| 51 | {
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| 52 | // add the bounding box
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| 53 | PolygonContainer polygons;
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| 54 | sceneBox.ExtractPolygons(polygons);
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| 55 |
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| 56 | Polyhedron *oldPolyhedron = new Polyhedron(polygons);
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| 57 |
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| 58 | if (!oldPolyhedron->Valid()) cerr << "******************* not valid!! ************* " << endl;
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| 59 |
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| 60 | vector<Plane3>::const_iterator it, it_end = planes.end();
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| 61 |
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| 62 | Polyhedron *newPolyhedron = NULL;
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| 63 |
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| 64 | // intersect bounding box with planes
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| 65 | for (it = planes.begin(); it != it_end; ++ it)
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| 66 | {
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| 67 | Plane3 plane = *it;
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| 68 |
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| 69 | newPolyhedron = oldPolyhedron->CalcIntersection(plane);
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| 70 |
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| 71 | if (!newPolyhedron)
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| 72 | {
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| 73 | cerr << "polyhedron not valid or NULL!" << endl;
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| 74 | return NULL;
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| 75 | }
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| 76 |
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| 77 | DEL_PTR(oldPolyhedron);
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| 78 | oldPolyhedron = newPolyhedron;
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| 79 | }
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| 80 |
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| 81 | return newPolyhedron;
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| 82 | }
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| 83 |
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| 84 |
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[2912] | 85 | Polyhedron::~Polyhedron()
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| 86 | {
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| 87 | CLEAR_CONTAINER(mPolygons);
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| 88 | }
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| 89 |
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| 90 |
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| 91 | int Polyhedron::NumPolygons() const
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| 92 | {
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| 93 | return (int)mPolygons.size();
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| 94 | }
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| 95 |
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| 96 |
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| 97 | void Polyhedron::Add(Polygon3 *p)
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| 98 | {
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| 99 | mPolygons.push_back(p);
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| 100 | mBox.Include(*p);
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| 101 | }
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| 102 |
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| 103 |
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| 104 | const PolygonContainer &Polyhedron::GetPolygons() const
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| 105 | {
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| 106 | return mPolygons;
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| 107 | }
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| 108 |
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| 109 |
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| 110 | float Polyhedron::GetArea() const
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| 111 | {
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| 112 | float area = 0;
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| 113 |
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| 114 | for (size_t i = 0; i < mPolygons.size(); ++ i)
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| 115 | {
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| 116 | area += mPolygons[i]->GetArea();
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| 117 | }
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| 118 |
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| 119 | return area;
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| 120 | }
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| 121 |
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| 122 |
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[2913] | 123 |
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[2912] | 124 | float Polyhedron::GetVolume() const
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| 125 | {
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| 126 | // computes volume by tetrahedralization of the geometry
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| 127 | // We just compute the sum of the tetrahedron volumes
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| 128 | float volume = 0;
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| 129 | const float f = 1.0f / 6.0f;
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| 130 |
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| 131 | PolygonContainer::const_iterator pit, pit_end = mPolygons.end();
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| 132 |
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| 133 | // note: can take arbitrary point, e.g., the origin. However,
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| 134 | // we rather take the center of mass to prevents precision errors
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| 135 | const Vector3 center = CenterOfMass();
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| 136 |
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| 137 | for (pit = mPolygons.begin(); pit != pit_end; ++ pit)
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| 138 | {
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| 139 | Polygon3 *poly = *pit;
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| 140 | const Vector3 v0 = poly->mVertices[0] - center;
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| 141 |
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| 142 | for (int i = 1; i < (int)poly->mVertices.size() - 1; ++ i)
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| 143 | {
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| 144 | const Vector3 v1 = poly->mVertices[i] - center;
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| 145 | const Vector3 v2 = poly->mVertices[i + 1] - center;
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| 146 |
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| 147 | // more robust version using abs and the center of mass
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| 148 | volume += fabs (f * (DotProd(v0, CrossProd(v1, v2))));
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| 149 | }
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| 150 | }
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| 151 |
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| 152 | return volume;
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| 153 | }
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| 154 |
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| 155 |
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| 156 | AxisAlignedBox3 Polyhedron::GetBoundingBox() const
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| 157 | {
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| 158 | return mBox;
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| 159 | }
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| 160 |
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| 161 |
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| 162 | int Polyhedron::Side(const Plane3 &plane) const
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| 163 | {
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| 164 | int boxSide = mBox.Side(plane);
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[2913] | 165 |
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[2912] | 166 | // plane does not intersect bounding box
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| 167 | if (boxSide != 0) return boxSide;
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| 168 |
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| 169 | PolygonContainer::const_iterator it, it_end = mPolygons.end();
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| 170 |
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| 171 | int s = 0;
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| 172 |
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| 173 | for (it = mPolygons.begin(); it != it_end; ++ it)
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| 174 | {
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| 175 | const int side = (*it)->Side(plane, epsilon);
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| 176 |
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[2913] | 177 | if (side == 0) // intersects polygon => intersects
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| 178 | return 0;
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| 179 | else if (side != 0)
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[2912] | 180 | {
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| 181 | if (side == -s)
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| 182 | return 0; // sign changed => intersects
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| 183 |
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| 184 | s = side;
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| 185 | }
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| 186 | }
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| 187 |
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| 188 | return s;
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| 189 | }
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| 190 |
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| 191 |
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| 192 | Vector3 Polyhedron::CenterOfMass() const
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| 193 | {
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| 194 | int n = 0;
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| 195 |
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| 196 | Vector3 center(0,0,0);
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| 197 |
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| 198 | PolygonContainer::const_iterator pit, pit_end = mPolygons.end();
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| 199 |
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| 200 | for (pit = mPolygons.begin(); pit != pit_end; ++ pit)
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| 201 | {
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| 202 | Polygon3 *poly = *pit;
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| 203 |
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| 204 | VertexArray::const_iterator vit, vit_end = poly->mVertices.end();
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| 205 |
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| 206 | for(vit = poly->mVertices.begin(); vit != vit_end; ++ vit)
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| 207 | {
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| 208 | center += *vit;
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| 209 | ++ n;
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| 210 | }
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| 211 | }
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| 212 |
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| 213 | return center / (float)n;
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| 214 | }
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| 215 |
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| 216 |
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| 217 | bool Polyhedron::Valid() const
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| 218 | {
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| 219 | // polyhedron is degenerated
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| 220 | if (mPolygons.size() < 3)
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| 221 | return false;
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[2913] | 222 |
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| 223 | const Vector3 center = CenterOfMass();
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| 224 |
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| 225 | PolygonContainer::const_iterator pit, pit_end = mPolygons.end();
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| 226 |
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| 227 | for (pit = mPolygons.begin(); pit != pit_end; ++ pit)
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| 228 | {
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| 229 | Polygon3 *poly = *pit;
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| 230 | Plane3 plane = poly->GetSupportingPlane();
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| 231 |
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| 232 | float dist = plane.Distance(center);
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| 233 | //cout << "dist: " << dist<< endl;
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| 234 | if (dist > 0)
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| 235 | return false;
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| 236 | }
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| 237 | return true;
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[2912] | 238 | }
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| 239 |
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| 240 |
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| 241 | Polyhedron *Polyhedron::CalcIntersection(const Plane3 &splitPlane) const
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| 242 | {
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| 243 | // first test plane intersection with geometry
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| 244 | const int intersect = Side(splitPlane);
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| 245 |
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| 246 | if (intersect == 1)
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[2913] | 247 | {
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[2912] | 248 | // on the other side of the plane, the intersection is empty
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[2913] | 249 | return NULL;
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| 250 | }
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[2912] | 251 | else if (intersect == -1)
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[2913] | 252 | {
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[2912] | 253 | // does not intersect, just return a copy
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[2913] | 254 | return new Polyhedron(*this);
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| 255 | }
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[2912] | 256 |
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[2913] | 257 | // polyhedron is intersected: create new polyhedron
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| 258 | Polyhedron *clippedPolyhedron = new Polyhedron();
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[2912] | 259 |
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[2913] | 260 |
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[2912] | 261 | //////////
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[2913] | 262 | //-- create and add new polygon to close polyhedron
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[2912] | 263 |
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| 264 | // get cross section of new polygon
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| 265 | Polygon3 *planePoly = mBox.CrossSection(splitPlane);
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| 266 |
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| 267 | // create new face: split polygon with all other polygons
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| 268 | planePoly = SplitPolygon(planePoly);
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| 269 |
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[2913] | 270 | // something is wrong, probably some numerical error
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[2912] | 271 | if (!planePoly)
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| 272 | {
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| 273 | cerr << "should not happen" << endl;
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[2913] | 274 | return new Polyhedron(*this);
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[2912] | 275 | }
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| 276 |
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| 277 | // add the new polygon to the polyhedron
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| 278 | clippedPolyhedron->Add(planePoly);
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| 279 |
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| 280 |
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| 281 |
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| 282 | /////////////
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[2913] | 283 | //-- clip polyhedron: plane splits all polygons
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[2912] | 284 |
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| 285 | for (int i = 0; i < (int)mPolygons.size(); ++ i)
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| 286 | {
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| 287 | Polygon3 *poly = mPolygons[i];
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| 288 |
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| 289 | const int cf = mPolygons[i]->ClassifyPlane(splitPlane, epsilon);
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| 290 |
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| 291 | switch (cf)
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| 292 | {
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| 293 | // split case: split polygon and add it
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| 294 | case Polygon3::SPLIT:
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| 295 | {
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| 296 | Polygon3 *poly = mPolygons[i];
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| 297 |
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| 298 | Polygon3 *frontPoly = new Polygon3();
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| 299 | Polygon3 *backPoly = new Polygon3();
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| 300 |
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| 301 | poly->Split(splitPlane, *frontPoly, *backPoly, epsilon);
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| 302 |
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| 303 | // we are only interested in the polytope behind the plane
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| 304 | DEL_PTR(frontPoly);
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| 305 |
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| 306 | if (backPoly->Valid(epsilon))
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| 307 | clippedPolyhedron->Add(backPoly);
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| 308 | else
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| 309 | DEL_PTR(backPoly);
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| 310 | }
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| 311 |
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| 312 | break;
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| 313 | case Polygon3::BACK_SIDE:
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| 314 | case Polygon3::COINCIDENT:
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| 315 | clippedPolyhedron->Add(new Polygon3(mPolygons[i]->mVertices));
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| 316 | break;
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| 317 | default:
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| 318 | // polygon is not in intersection
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| 319 | break;
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| 320 | }
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| 321 | }
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| 322 |
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| 323 | return clippedPolyhedron;
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| 324 | }
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| 325 |
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| 326 |
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| 327 | Polygon3 *Polyhedron::SplitPolygon(Polygon3 *polygon) const
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| 328 | {
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| 329 | if (!polygon->Valid(epsilon)) DEL_PTR(polygon);
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| 330 |
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| 331 | // polygon is split by all other planes
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| 332 | for (size_t i = 0; (i < mPolygons.size()) && polygon; ++ i)
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| 333 | {
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| 334 | const Plane3 plane = mPolygons[i]->GetSupportingPlane();
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| 335 |
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| 336 | int cf = polygon->ClassifyPlane(plane, epsilon);
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| 337 |
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| 338 | // split new polygon with all previous planes
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| 339 | switch (cf)
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| 340 | {
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| 341 | case Polygon3::SPLIT:
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| 342 | {
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| 343 | Polygon3 *frontPoly = new Polygon3();
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| 344 | Polygon3 *backPoly = new Polygon3();
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| 345 |
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| 346 | polygon->Split(plane, *frontPoly, *backPoly, epsilon);
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| 347 |
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| 348 | // don't need these anymore
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| 349 | DEL_PTR(frontPoly);
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| 350 | DEL_PTR(polygon);
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| 351 |
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| 352 | // back polygon belongs to geometry
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| 353 | if (backPoly->Valid(epsilon))
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| 354 | polygon = backPoly;
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| 355 | else
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| 356 | DEL_PTR(backPoly);
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| 357 | }
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| 358 | break;
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| 359 | case Polygon3::FRONT_SIDE:
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| 360 | cerr << "SplitPolygon: should not come here" << endl;
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| 361 | DEL_PTR(polygon);
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| 362 | break;
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| 363 | // polygon is taken as it is
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| 364 | case Polygon3::BACK_SIDE:
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| 365 | case Polygon3::COINCIDENT:
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| 366 | default:
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| 367 | break;
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| 368 | }
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| 369 | }
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| 370 |
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| 371 | return polygon;
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| 372 | }
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| 373 |
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| 374 |
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| 375 | void Polyhedron::CollectVertices(VertexArray &vertices) const
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| 376 | {
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| 377 | PolygonContainer::const_iterator it, it_end = mPolygons.end();
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| 378 |
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| 379 | for (it = mPolygons.begin(); it != it_end; ++ it)
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| 380 | {
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| 381 | Polygon3 *poly = *it;
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| 382 |
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| 383 | VertexArray::const_iterator vit, vit_end = poly->mVertices.end();
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| 384 |
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| 385 | for (vit = poly->mVertices.begin(); vit != vit_end; ++ vit)
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| 386 | {
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| 387 | vertices.push_back(*vit);
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| 388 | }
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| 389 | }
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| 390 | }
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| 391 |
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| 392 |
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| 393 | }
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