[2912] | 1 | #include "Polygon3.h"
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| 2 | #include "AxisAlignedBox3.h"
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| 3 | #include "Plane3.h"
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| 4 |
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| 5 |
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| 6 | using namespace std;
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| 7 |
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| 8 | namespace CHCDemoEngine
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| 9 | {
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| 10 |
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| 11 | Polygon3::Polygon3()
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| 12 | {
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| 13 | }
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| 14 |
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| 15 |
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| 16 | Polygon3::Polygon3(const VertexArray &vertices)
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| 17 | {
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| 18 | mVertices.reserve(vertices.size());
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| 19 | mVertices = vertices;
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| 20 | }
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| 21 |
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| 22 |
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| 23 | Polygon3::~Polygon3()
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| 24 | {
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| 25 | }
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| 26 |
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| 27 |
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| 28 | Plane3 Polygon3::GetSupportingPlane() const
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| 29 | {
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| 30 | return Plane3(mVertices[0], mVertices[1], mVertices[2]);
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| 31 | }
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| 32 |
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| 33 |
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| 34 | Vector3 Polygon3::GetNormal() const
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| 35 | {
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| 36 | return Normalize(CrossProd(mVertices[2] - mVertices[1],
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| 37 | mVertices[0] - mVertices[1]));
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| 38 | }
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| 39 |
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| 40 |
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| 41 | void Polygon3::Split(const Plane3 &partition,
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| 42 | Polygon3 &front,
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| 43 | Polygon3 &back, float epsilon)
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| 44 | {
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| 45 | Vector3 ptA = mVertices.back();
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| 46 | int sideA = partition.Side(ptA, epsilon);
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| 47 | bool foundSplit = false;
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| 48 | Vector3 lastSplit;
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| 49 |
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| 50 | /////////////
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| 51 | //-- find line - plane intersections
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| 52 |
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| 53 | VertexArray::const_iterator it, it_end = mVertices.end();
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| 54 |
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| 55 | for (it = mVertices.begin(); it != it_end; ++ it)
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| 56 | {
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| 57 | Vector3 ptB = *it;
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| 58 | int sideB = partition.Side(ptB, epsilon);
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| 59 |
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| 60 | // vertices on different sides => split
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| 61 | if (sideB > 0)
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| 62 | {
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| 63 | if (sideA < 0)
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| 64 | {
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| 65 | //-- plane - line intersection
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| 66 | Vector3 splitPt = partition.FindIntersection(ptA, ptB);
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| 67 |
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| 68 | // test if split point not too close to previous split point
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| 69 | if (!foundSplit || (!EpsilonEqualV3(splitPt, lastSplit, epsilon)))
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| 70 | {
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| 71 | // add vertex to both polygons
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| 72 | front.mVertices.push_back(splitPt);
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| 73 | back.mVertices.push_back(splitPt);
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| 74 |
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| 75 | lastSplit = splitPt;
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| 76 | foundSplit = true;
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| 77 | }
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| 78 | }
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| 79 | front.mVertices.push_back(ptB);
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| 80 | }
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| 81 | else if (sideB < 0)
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| 82 | {
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| 83 | if (sideA > 0)
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| 84 | {
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| 85 | ////////////
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| 86 | //-- plane - line intersection
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| 87 |
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| 88 | Vector3 splitPt = partition.FindIntersection(ptA, ptB);
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| 89 |
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| 90 | // test if split point not too close to previous split point
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| 91 | if (!foundSplit || (!EpsilonEqualV3(splitPt, lastSplit, epsilon)))
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| 92 | {
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| 93 | // add vertex to both polygons
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| 94 | front.mVertices.push_back(splitPt);
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| 95 | back.mVertices.push_back(splitPt);
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| 96 |
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| 97 | lastSplit = splitPt;
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| 98 | foundSplit = true;
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| 99 | }
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| 100 | }
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| 101 |
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| 102 | back.mVertices.push_back(ptB);
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| 103 | }
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| 104 | else
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| 105 | {
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| 106 | // vertex on plane => add vertex to both polygons
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| 107 | front.mVertices.push_back(ptB);
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| 108 | back.mVertices.push_back(ptB);
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| 109 | }
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| 110 |
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| 111 | ptA = ptB;
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| 112 | sideA = sideB;
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| 113 | }
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| 114 | }
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| 115 |
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| 116 |
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| 117 | float Polygon3::GetArea() const
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| 118 | {
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| 119 | Vector3 v = CrossProd(mVertices.back(), mVertices.front());
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| 120 |
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| 121 | for (int i=0; i < mVertices.size() - 1; ++i)
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| 122 | v += CrossProd(mVertices[i], mVertices[i+1]);
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| 123 |
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| 124 | return 0.5f * fabs(DotProd(GetNormal(), v));
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| 125 | }
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| 126 |
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| 127 |
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| 128 | int Polygon3::Side(const Plane3 &plane,
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| 129 | const float epsilon) const
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| 130 | {
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| 131 | int classification = ClassifyPlane(plane, epsilon);
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| 132 |
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| 133 | if (classification == BACK_SIDE)
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| 134 | return -1;
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| 135 | else if (classification == FRONT_SIDE)
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| 136 | return 1;
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[2913] | 137 |
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| 138 | // plane splits polygon or is coincident
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[2912] | 139 | return 0;
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| 140 | }
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| 141 |
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| 142 |
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| 143 | int Polygon3::ClassifyPlane(const Plane3 &plane,
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| 144 | const float epsilon) const
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| 145 | {
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| 146 | VertexArray::const_iterator it, it_end = mVertices.end();
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| 147 |
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| 148 | bool onFrontSide = false;
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| 149 | bool onBackSide = false;
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| 150 |
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| 151 | int count = 0;
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| 152 | // find possible line-plane intersections
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| 153 | for (it = mVertices.begin(); it != it_end; ++ it)
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| 154 | {
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| 155 | const int side = plane.Side(*it, epsilon);
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| 156 |
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| 157 | if (side > 0)
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| 158 | {
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| 159 | onFrontSide = true;
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| 160 | }
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| 161 | else if (side < 0)
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| 162 | {
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| 163 | onBackSide = true;
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| 164 | }
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| 165 |
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| 166 | //TODO: check if split goes through vertex
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| 167 | if (onFrontSide && onBackSide) // split
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| 168 | {
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| 169 | return SPLIT;
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| 170 | }
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| 171 | // 3 vertices enough to decide if coincident
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| 172 | else if (((++ count) >= 3) && !onFrontSide && !onBackSide)
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| 173 | {
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| 174 | return COINCIDENT;
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| 175 | }
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| 176 | }
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| 177 |
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| 178 | if (onBackSide)
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| 179 | {
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| 180 | return BACK_SIDE;
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| 181 | }
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| 182 | else if (onFrontSide)
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| 183 | {
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| 184 | return FRONT_SIDE;
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| 185 | }
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| 186 |
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| 187 | return COINCIDENT; // plane and polygon are coincident
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| 188 | }
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| 189 |
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| 190 |
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| 191 | Vector3 Polygon3::Center() const
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| 192 | {
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| 193 | int i;
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| 194 | Vector3 sum = mVertices[0];
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| 195 | for (i=1; i < mVertices.size(); i++)
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| 196 | sum += mVertices[i];
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| 197 |
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| 198 | return sum / (float)i;
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| 199 | }
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| 200 |
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| 201 |
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| 202 | bool Polygon3::Valid(const float epsilon) const
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| 203 | {
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| 204 | if (mVertices.size() < 3)
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| 205 | return false;
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[2913] | 206 | #if 0
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[2912] | 207 | // matt: removed for performance issues
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| 208 | // check if area exceeds certain size
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| 209 | if (GetArea() < 1e-10)
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| 210 | {
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| 211 | cerr << "area too small: " << GetArea() << std::endl;
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| 212 | return false;
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| 213 | }
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| 214 |
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| 215 | Vector3 vtx = mVertices.back();
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| 216 | VertexArray::const_iterator it, it_end = mVertices.end();
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| 217 |
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| 218 | for (it = mVertices.begin(); it != it_end; ++it)
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| 219 | {
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| 220 | if (EpsilonEqualV3(vtx, *it, epsilon))
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| 221 | {
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| 222 | cerr << "Double vertices:\n" << *this << endl;
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| 223 | return false;
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| 224 | }
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| 225 | vtx = *it;
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| 226 | }
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[2913] | 227 | #endif
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[2912] | 228 | return true;
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| 229 | }
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| 230 |
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| 231 |
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| 232 | // int_lineseg returns 1 if the given line segment intersects a 2D
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| 233 | // ray travelling in the positive X direction. This is used in the
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| 234 | // Jordan curve computation for polygon intersection.
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| 235 | inline int int_lineseg(float px,
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| 236 | float py,
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| 237 | float u1,
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| 238 | float v1,
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| 239 | float u2,
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| 240 | float v2)
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| 241 | {
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| 242 | float t;
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| 243 | float ydiff;
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| 244 |
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| 245 | u1 -= px; u2 -= px; // translate line
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| 246 | v1 -= py; v2 -= py;
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| 247 |
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| 248 | if ((v1 > 0 && v2 > 0) ||
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| 249 | (v1 < 0 && v2 < 0) ||
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| 250 | (u1 < 0 && u2 < 0))
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| 251 | return 0;
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| 252 |
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| 253 | if (u1 > 0 && u2 > 0)
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| 254 | return 1;
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| 255 |
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| 256 | ydiff = v2 - v1;
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| 257 |
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| 258 | if (fabs(ydiff) < Limits::Small)
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| 259 | {
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| 260 | // denominator near 0
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| 261 | if (((fabs(v1) > Limits::Small) || (u1 > 0) || (u2 > 0)))
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| 262 | return 0;
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| 263 |
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| 264 | return 1;
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| 265 | }
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| 266 |
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| 267 | t = -v1 / ydiff; // Compute parameter
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| 268 |
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| 269 | return (u1 + t * (u2 - u1)) > 0;
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| 270 | }
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| 271 |
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| 272 |
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| 273 | AxisAlignedBox3 Polygon3::GetBoundingBox() const
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| 274 | {
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| 275 | AxisAlignedBox3 box;
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| 276 | box.Initialize();
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| 277 |
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| 278 | VertexArray::const_iterator vit, vit_end = mVertices.end();
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| 279 |
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| 280 | for (vit = mVertices.begin(); vit != vit_end; ++ vit)
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| 281 | {
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| 282 | box.Include(*vit);
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| 283 | }
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| 284 |
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| 285 | return box;
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| 286 | }
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| 287 |
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| 288 |
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| 289 | } |
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