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