1 | #include <Eigen/StdVector>
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2 | #include <unsupported/Eigen/BVH>
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3 | #include <iostream>
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4 |
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5 | using namespace Eigen;
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6 | typedef AlignedBox<double, 2> Box2d;
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7 |
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8 | namespace Eigen {
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9 | namespace internal {
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10 | Box2d bounding_box(const Vector2d &v) { return Box2d(v, v); } //compute the bounding box of a single point
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11 | }
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12 | }
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13 |
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14 | struct PointPointMinimizer //how to compute squared distances between points and rectangles
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15 | {
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16 | PointPointMinimizer() : calls(0) {}
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17 | typedef double Scalar;
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18 |
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19 | double minimumOnVolumeVolume(const Box2d &r1, const Box2d &r2) { ++calls; return r1.squaredExteriorDistance(r2); }
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20 | double minimumOnVolumeObject(const Box2d &r, const Vector2d &v) { ++calls; return r.squaredExteriorDistance(v); }
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21 | double minimumOnObjectVolume(const Vector2d &v, const Box2d &r) { ++calls; return r.squaredExteriorDistance(v); }
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22 | double minimumOnObjectObject(const Vector2d &v1, const Vector2d &v2) { ++calls; return (v1 - v2).squaredNorm(); }
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23 |
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24 | int calls;
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25 | };
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26 |
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27 | int main()
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28 | {
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29 | typedef std::vector<Vector2d, aligned_allocator<Vector2d> > StdVectorOfVector2d;
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30 | StdVectorOfVector2d redPoints, bluePoints;
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31 | for(int i = 0; i < 100; ++i) { //initialize random set of red points and blue points
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32 | redPoints.push_back(Vector2d::Random());
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33 | bluePoints.push_back(Vector2d::Random());
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34 | }
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35 |
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36 | PointPointMinimizer minimizer;
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37 | double minDistSq = std::numeric_limits<double>::max();
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38 |
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39 | //brute force to find closest red-blue pair
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40 | for(int i = 0; i < (int)redPoints.size(); ++i)
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41 | for(int j = 0; j < (int)bluePoints.size(); ++j)
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42 | minDistSq = std::min(minDistSq, minimizer.minimumOnObjectObject(redPoints[i], bluePoints[j]));
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43 | std::cout << "Brute force distance = " << sqrt(minDistSq) << ", calls = " << minimizer.calls << std::endl;
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44 |
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45 | //using BVH to find closest red-blue pair
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46 | minimizer.calls = 0;
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47 | KdBVH<double, 2, Vector2d> redTree(redPoints.begin(), redPoints.end()), blueTree(bluePoints.begin(), bluePoints.end()); //construct the trees
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48 | minDistSq = BVMinimize(redTree, blueTree, minimizer); //actual BVH minimization call
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49 | std::cout << "BVH distance = " << sqrt(minDistSq) << ", calls = " << minimizer.calls << std::endl;
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50 |
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51 | return 0;
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52 | }
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