1 | #include "Polygon3.h"
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2 | #include "Mesh.h"
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3 | #include "AxisAlignedBox3.h"
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4 | #include "Ray.h"
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5 | #include "Triangle3.h"
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6 |
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7 | Polygon3::Polygon3():
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8 | mMaterial(NULL), mParent(NULL), mPiercingRays(0)
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9 | {
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10 | // mostly there will be triangles
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11 | //mVertices.reserve(3);
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12 | }
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13 |
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14 | Polygon3::Polygon3(const VertexContainer &vertices):
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15 | mMaterial(NULL), mParent(NULL), mPiercingRays(0)
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16 | {
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17 | mVertices.reserve(vertices.size());
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18 | mVertices = vertices;
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19 | }
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20 |
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21 |
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22 | Polygon3::Polygon3(MeshInstance *parent):
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23 | mMaterial(NULL), mParent(parent), mPiercingRays(0)
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24 | {}
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25 |
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26 |
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27 | Polygon3::Polygon3(Face *face, Mesh *parentMesh):
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28 | mMaterial(NULL), mParent(NULL), mPiercingRays(0)
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29 | {
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30 | mVertices.reserve(face->mVertexIndices.size());
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31 |
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32 | VertexIndexContainer::iterator it = face->mVertexIndices.begin();
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33 | for (; it != face->mVertexIndices.end(); ++it)
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34 | {
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35 | mVertices.push_back(parentMesh->mVertices[*it]);
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36 | }
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37 |
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38 | mMaterial = parentMesh->mMaterial;
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39 | }
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40 |
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41 |
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42 | Plane3 Polygon3::GetSupportingPlane() const
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43 | {
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44 | return Plane3(mVertices[0], mVertices[1], mVertices[2]);
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45 | }
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46 |
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47 |
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48 | Vector3 Polygon3::GetNormal() const
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49 | {
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50 | return Normalize(CrossProd(mVertices[2] - mVertices[1],
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51 | mVertices[0] - mVertices[1]));
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52 | }
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53 |
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54 | void Polygon3::Split(const Plane3 &partition,
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55 | Polygon3 &front,
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56 | Polygon3 &back,
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57 | const float epsilon)
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58 | {
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59 | Vector3 ptA = mVertices.back();
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60 |
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61 | int sideA = partition.Side(ptA, epsilon);
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62 |
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63 | VertexContainer::const_iterator it;
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64 |
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65 | Vector3 lastSplit;
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66 |
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67 | bool foundSplit = false;
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68 |
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69 | //-- find line - plane intersections
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70 | for (it = mVertices.begin(); it != mVertices.end(); ++ it)
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71 | {
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72 | Vector3 ptB = *it;
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73 | int sideB = partition.Side(ptB, epsilon);
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74 |
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75 | // vertices on different sides => split
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76 | if (sideB > 0)
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77 | {
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78 | if (sideA < 0)
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79 | {
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80 | //-- plane - line intersection
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81 | Vector3 splitPt = partition.FindIntersection(ptA, ptB);
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82 |
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83 | // test if split point not too close to previous split point
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84 | if (!foundSplit || (!EpsilonEqualV3(splitPt, lastSplit, epsilon)))
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85 | {
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86 | // add vertex to both polygons
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87 | front.mVertices.push_back(splitPt);
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88 | back.mVertices.push_back(splitPt);
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89 |
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90 | lastSplit = splitPt;
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91 | foundSplit = true;
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92 | }
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93 | }
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94 | front.mVertices.push_back(ptB);
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95 | }
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96 | else if (sideB < 0)
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97 | {
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98 | if (sideA > 0)
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99 | {
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100 | //-- plane - line intersection
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101 | Vector3 splitPt = partition.FindIntersection(ptA, ptB);
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102 | // test if split point not too close to other split point
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103 | // test if split point not too close to previous split point
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104 | if (!foundSplit || (!EpsilonEqualV3(splitPt, lastSplit, epsilon)))
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105 | {
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106 | // add vertex to both polygons
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107 | front.mVertices.push_back(splitPt);
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108 | back.mVertices.push_back(splitPt);
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109 |
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110 | lastSplit = splitPt;
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111 | foundSplit = true;
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112 | }
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113 | }
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114 | back.mVertices.push_back(ptB);
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115 | }
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116 | else
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117 | {
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118 | // vertex on plane => add vertex to both polygons
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119 | front.mVertices.push_back(ptB);
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120 | back.mVertices.push_back(ptB);
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121 | }
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122 |
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123 | ptA = ptB;
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124 | sideA = sideB;
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125 | }
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126 | }
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127 |
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128 |
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129 | float Polygon3::GetArea() const
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130 | {
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131 | Vector3 v = CrossProd(mVertices.back(), mVertices.front());
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132 |
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133 | for (int i=0; i < mVertices.size() - 1; ++i)
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134 | v += CrossProd(mVertices[i], mVertices[i+1]);
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135 |
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136 | return 0.5f * fabs(DotProd(GetNormal(), v));
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137 | }
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138 |
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139 |
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140 | int Polygon3::Side(const Plane3 &plane,
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141 | const float epsilon) const
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142 | {
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143 | int classification = ClassifyPlane(plane, epsilon);
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144 |
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145 | if (classification == BACK_SIDE)
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146 | return -1;
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147 | else if (classification == FRONT_SIDE)
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148 | return 1;
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149 | // plane splits polygon
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150 | return 0;
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151 | }
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152 |
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153 |
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154 | int Polygon3::ClassifyPlane(const Plane3 &plane,
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155 | const float epsilon) const
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156 | {
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157 | VertexContainer::const_iterator it, it_end = mVertices.end();
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158 |
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159 | bool onFrontSide = false;
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160 | bool onBackSide = false;
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161 |
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162 | int count = 0;
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163 | // find possible line-plane intersections
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164 | for (it = mVertices.begin(); it != it_end; ++ it)
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165 | {
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166 | const int side = plane.Side(*it, epsilon);
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167 |
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168 | if (side > 0)
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169 | onFrontSide = true;
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170 | else if (side < 0)
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171 | onBackSide = true;
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172 |
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173 | //TODO: check if split goes through vertex
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174 | if (onFrontSide && onBackSide) // split
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175 | {
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176 | return SPLIT;
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177 | }
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178 | // 3 vertices enough to decide coincident
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179 | else if (((++ count) >= 3) && !onFrontSide && !onBackSide)
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180 | {
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181 | return COINCIDENT;
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182 | }
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183 | }
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184 |
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185 | if (onBackSide)
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186 | {
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187 | return BACK_SIDE;
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188 | }
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189 | else if (onFrontSide)
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190 | {
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191 | return FRONT_SIDE;
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192 | }
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193 |
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194 | return COINCIDENT; // plane and polygon are coincident
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195 | }
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196 |
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197 |
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198 | Vector3
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199 | Polygon3::Center() const
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200 | {
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201 | int i;
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202 | Vector3 sum = mVertices[0];
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203 | for (i=1; i < mVertices.size(); i++)
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204 | sum += mVertices[i];
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205 |
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206 | return sum/(float)i;
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207 | }
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208 |
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209 |
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210 | void
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211 | Polygon3::Scale(const float scale)
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212 | {
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213 | int i;
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214 | Vector3 center = Center();
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215 | for (i=0; i < mVertices.size(); i++) {
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216 | mVertices[i] = center + scale*(mVertices[i] - center);
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217 | }
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218 | }
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219 |
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220 | bool Polygon3::Valid(const float epsilon) const
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221 | {
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222 | if (mVertices.size() < 3)
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223 | return false;
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224 |
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225 | //TODO: remove for performance
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226 | #if 1
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227 | if (1)
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228 | {
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229 | // check if area exceeds certain size
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230 | if (GetArea() < AREA_LIMIT)
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231 | {
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232 | Debug << "area too small: " << GetArea() << endl;
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233 | return false;
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234 | }
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235 | }
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236 |
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237 | if (1)
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238 | {
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239 | Vector3 vtx = mVertices.back();
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240 | VertexContainer::const_iterator it, it_end = mVertices.end();
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241 |
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242 | for (it = mVertices.begin(); it != it_end; ++it)
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243 | {
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244 | if (EpsilonEqualV3(vtx, *it, 0.0001))
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245 | {
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246 | //Debug << "Malformed vertices:\n" << *this << endl;
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247 | return false;
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248 | }
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249 | vtx = *it;
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250 | }
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251 | }
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252 | #endif
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253 |
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254 | return true;
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255 | }
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256 |
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257 |
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258 | void Polygon3::IncludeInBox(const PolygonContainer &polys, AxisAlignedBox3 &box)
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259 | {
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260 | PolygonContainer::const_iterator it, it_end = polys.end();
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261 |
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262 | for (it = polys.begin(); it != it_end; ++ it)
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263 | box.Include(*(*it));
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264 | }
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265 |
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266 |
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267 | // int_lineseg returns 1 if the given line segment intersects a 2D
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268 | // ray travelling in the positive X direction. This is used in the
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269 | // Jordan curve computation for polygon intersection.
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270 | inline int
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271 | int_lineseg(float px,
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272 | float py,
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273 | float u1,
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274 | float v1,
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275 | float u2,
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276 | float v2)
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277 | {
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278 | float t;
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279 | float ydiff;
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280 |
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281 | u1 -= px; u2 -= px; // translate line
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282 | v1 -= py; v2 -= py;
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283 |
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284 | if ((v1 > 0 && v2 > 0) ||
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285 | (v1 < 0 && v2 < 0) ||
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286 | (u1 < 0 && u2 < 0))
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287 | return 0;
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288 |
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289 | if (u1 > 0 && u2 > 0)
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290 | return 1;
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291 |
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292 | ydiff = v2 - v1;
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293 |
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294 | if (fabs(ydiff) < Limits::Small)
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295 | { // denominator near 0
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296 | if (((fabs(v1) > Limits::Small) || (u1 > 0) || (u2 > 0)))
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297 | return 0;
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298 | return 1;
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299 | }
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300 |
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301 | t = -v1 / ydiff; // Compute parameter
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302 |
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303 | return (u1 + t * (u2 - u1)) > 0;
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304 | }
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305 |
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306 |
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307 | int Polygon3::CastRay(const Ray &ray, float &t, const float nearestT)
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308 | {
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309 | Plane3 plane = GetSupportingPlane();
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310 | float dot = DotProd(plane.mNormal, ray.GetDir());
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311 |
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312 | // Watch for near-zero denominator
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313 | // ONLY single sided polygons!!!!!
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314 | if (dot > -Limits::Small)
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315 | // if (fabs(dot) < Limits::Small)
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316 | return Ray::NO_INTERSECTION;
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317 |
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318 | t = (-plane.mD - DotProd(plane.mNormal, ray.GetLoc())) / dot;
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319 |
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320 | if (t <= Limits::Small)
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321 | return Ray::INTERSECTION_OUT_OF_LIMITS;
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322 |
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323 | if (t >= nearestT) {
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324 | return Ray::INTERSECTION_OUT_OF_LIMITS; // no intersection was found
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325 | }
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326 |
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327 | int count = 0;
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328 | float u, v, u1, v1, u2, v2;
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329 | int i;
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330 |
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331 | int paxis = plane.mNormal.DrivingAxis();
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332 |
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333 | // Project the intersection point onto the coordinate plane
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334 | // specified by which.
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335 | ray.Extrap(t).ExtractVerts(&u, &v, paxis);
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336 |
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337 | int size = (int)mVertices.size();
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338 |
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339 | mVertices.back().ExtractVerts(&u1, &v1, paxis );
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340 |
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341 | if (0 && size <= 4)
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342 | {
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343 | // assume a convex face
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344 | for (i = 0; i < size; i++)
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345 | {
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346 | mVertices[i].ExtractVerts(&u2, &v2, paxis);
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347 |
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348 | // line u1, v1, u2, v2
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349 |
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350 | if ((v2 - v1)*(u1 - u) > (u2 - u1)*(v1 - v))
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351 | return Ray::NO_INTERSECTION;
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352 |
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353 | u1 = u2;
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354 | v1 = v2;
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355 | }
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356 |
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357 | return Ray::INTERSECTION;
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358 | }
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359 |
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360 | // We're stuck with the Jordan curve computation. Count number
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361 | // of intersections between the line segments the polygon comprises
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362 | // with a ray originating at the point of intersection and
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363 | // travelling in the positive X direction.
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364 | for (i = 0; i < size; i++)
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365 | {
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366 | mVertices[i].ExtractVerts(&u2, &v2, paxis);
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367 |
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368 | count += (int_lineseg(u, v, u1, v1, u2, v2) != 0);
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369 |
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370 | u1 = u2;
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371 | v1 = v2;
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372 | }
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373 |
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374 | // We hit polygon if number of intersections is odd.
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375 | return (count & 1) ? Ray::INTERSECTION : Ray::NO_INTERSECTION;
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376 | }
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377 |
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378 |
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379 | void Polygon3::InheritRays(Polygon3 &front_piece,
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380 | Polygon3 &back_piece) const
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381 | {
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382 | if (mPiercingRays.empty())
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383 | return;
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384 |
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385 | RayContainer::const_iterator it,
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386 | it_end = mPiercingRays.end();
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387 |
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388 | for (it = mPiercingRays.begin(); it != it_end; ++ it)
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389 | {
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390 | switch((*it)->GetId())
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391 | {
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392 | case Ray::BACK:
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393 | back_piece.mPiercingRays.push_back(*it);
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394 | break;
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395 | case Ray::FRONT:
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396 | front_piece.mPiercingRays.push_back(*it);
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397 | break;
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398 | case Ray::FRONT_BACK:
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399 | back_piece.mPiercingRays.push_back(*it);
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400 | break;
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401 | case Ray::BACK_FRONT:
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402 | front_piece.mPiercingRays.push_back(*it);
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403 | break;
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404 | default:
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405 | break;
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406 | }
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407 | }
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408 | }
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409 |
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410 |
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411 | int Polygon3::ClassifyPlane(const PolygonContainer &polys,
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412 | const Plane3 &plane,
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413 | const float epsilon)
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414 | {
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415 | PolygonContainer::const_iterator it;
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416 |
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417 | bool onFrontSide = false;
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418 | bool onBackSide = false;
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419 |
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420 | // find intersections
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421 | for (it = polys.begin(); it != polys.end(); ++ it)
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422 | {
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423 | const int cf = (*it)->ClassifyPlane(plane, epsilon);
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424 |
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425 | if (cf == FRONT_SIDE)
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426 | onFrontSide = true;
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427 | else if (cf == BACK_SIDE)
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428 | onBackSide = true;
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429 |
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430 | if ((cf == SPLIT) || (cf == COINCIDENT) || (onFrontSide && onBackSide))
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431 | {
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432 | return SPLIT;
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433 | }
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434 | }
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435 |
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436 | if (onBackSide)
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437 | {
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438 | return BACK_SIDE;
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439 | }
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440 | else if (onFrontSide)
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441 | {
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442 | return FRONT_SIDE;
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443 | }
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444 |
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445 | return SPLIT;
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446 | }
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447 |
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448 |
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449 | int Polygon3::ParentObjectsSize(const PolygonContainer &polys)
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450 | {
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451 | int count = 0;
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452 |
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453 | PolygonContainer::const_iterator it, it_end = polys.end();
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454 |
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455 | MeshInstance::NewMail();
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456 |
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457 | for (it = polys.begin(); it != it_end; ++ it)
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458 | {
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459 | if ((*it)->mParent && !(*it)->mParent->Mailed())
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460 | {
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461 | ++ count;
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462 | (*it)->mParent->Mail();
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463 | }
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464 | }
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465 | return count;
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466 | }
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467 |
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468 |
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469 | float Polygon3::GetArea(const PolygonContainer &cell)
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470 | {
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471 | float area = 0;
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472 | PolygonContainer::const_iterator pit;
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473 |
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474 | for (pit = cell.begin(); pit != cell.end(); ++ pit)
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475 | {
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476 | area += (*pit)->GetArea();
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477 | }
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478 |
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479 | return area;
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480 | }
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481 |
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482 |
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483 | Polygon3 *Polygon3::CreateReversePolygon() const
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484 | {
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485 | Polygon3 *revPoly = new Polygon3();
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486 |
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487 | VertexContainer::const_reverse_iterator rit,
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488 | rit_end = mVertices.rend();
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489 |
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490 | for(rit = mVertices.rbegin(); rit != rit_end; ++ rit)
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491 | revPoly->mVertices.push_back(*rit);
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492 |
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493 | return revPoly;
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494 | }
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495 |
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496 |
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497 | void Polygon3::Triangulate(vector<Triangle3> &triangles)
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498 | {
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499 | int i = 1;
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500 | int j = 0;
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501 | int k = (int)mVertices.size() - 1;
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502 | int count = 0;
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503 |
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504 | while (i < k)
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505 | {
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506 | triangles.push_back(Triangle3(mVertices[i], mVertices[j], mVertices[k]));
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507 |
|
---|
508 | if ((count ++) % 2)
|
---|
509 | j = i ++;
|
---|
510 | else
|
---|
511 | j = k --;
|
---|
512 | }
|
---|
513 | }
|
---|
514 |
|
---|
515 |
|
---|
516 | void Polygon3::Triangulate(VertexIndexContainer &indices)
|
---|
517 | {
|
---|
518 | int i = 1;
|
---|
519 | int j = 0;
|
---|
520 | int k = (int)mVertices.size() - 1;
|
---|
521 |
|
---|
522 | int count = 0;
|
---|
523 |
|
---|
524 | while (i < k)
|
---|
525 | {
|
---|
526 | indices.push_back(k);
|
---|
527 | indices.push_back(j);
|
---|
528 | indices.push_back(i);
|
---|
529 |
|
---|
530 | if ((count ++) % 2)
|
---|
531 | j = i ++;
|
---|
532 | else
|
---|
533 | j = k --;
|
---|
534 | }
|
---|
535 | }
|
---|
536 |
|
---|
537 |
|
---|
538 | void Polygon3::AddToMesh(Mesh &mesh)
|
---|
539 | {
|
---|
540 | const int n = (int)mesh.mVertices.size();
|
---|
541 |
|
---|
542 | //-- add the vertices
|
---|
543 | VertexContainer::const_iterator vit, vit_end = mVertices.end();
|
---|
544 | for (vit = mVertices.begin(); vit != vit_end; ++ vit)
|
---|
545 | {
|
---|
546 | mesh.mVertices.push_back(*vit);
|
---|
547 | }
|
---|
548 |
|
---|
549 | // one quad => no triangulation necessary
|
---|
550 | if ((int)mVertices.size() == 4)
|
---|
551 | {
|
---|
552 | mesh.AddFace(new Face(n, n + 1, n + 2, n + 3));
|
---|
553 | }
|
---|
554 | else
|
---|
555 | {
|
---|
556 | VertexIndexContainer indices;
|
---|
557 | Triangulate(indices);
|
---|
558 |
|
---|
559 | // add indices of triangle strip
|
---|
560 | for (int i = 0; i < (int)indices.size(); i += 3)
|
---|
561 | {
|
---|
562 | Face *face = new Face(n + indices[i],
|
---|
563 | n + indices[i + 1],
|
---|
564 | n + indices[i + 2]);
|
---|
565 | mesh.AddFace(face);
|
---|
566 | }
|
---|
567 | }
|
---|
568 | } |
---|