1 #include <Eigen/StdVector>
2 #include <unsupported/Eigen/BVH>
3 #include <iostream>
4
5 using namespace Eigen;
6 typedef AlignedBox<double, 2> Box2d;
7
8 namespace Eigen {
bounding_box(const Vector2d & v)9 Box2d bounding_box(const Vector2d &v) { return Box2d(v, v); } //compute the bounding box of a single point
10 }
11
12 struct PointPointMinimizer //how to compute squared distances between points and rectangles
13 {
PointPointMinimizerPointPointMinimizer14 PointPointMinimizer() : calls(0) {}
15 typedef double Scalar;
16
minimumOnVolumeVolumePointPointMinimizer17 double minimumOnVolumeVolume(const Box2d &r1, const Box2d &r2) { ++calls; return r1.squaredExteriorDistance(r2); }
minimumOnVolumeObjectPointPointMinimizer18 double minimumOnVolumeObject(const Box2d &r, const Vector2d &v) { ++calls; return r.squaredExteriorDistance(v); }
minimumOnObjectVolumePointPointMinimizer19 double minimumOnObjectVolume(const Vector2d &v, const Box2d &r) { ++calls; return r.squaredExteriorDistance(v); }
minimumOnObjectObjectPointPointMinimizer20 double minimumOnObjectObject(const Vector2d &v1, const Vector2d &v2) { ++calls; return (v1 - v2).squaredNorm(); }
21
22 int calls;
23 };
24
main()25 int main()
26 {
27 typedef std::vector<Vector2d, aligned_allocator<Vector2d> > StdVectorOfVector2d;
28 StdVectorOfVector2d redPoints, bluePoints;
29 for(int i = 0; i < 100; ++i) { //initialize random set of red points and blue points
30 redPoints.push_back(Vector2d::Random());
31 bluePoints.push_back(Vector2d::Random());
32 }
33
34 PointPointMinimizer minimizer;
35 double minDistSq = std::numeric_limits<double>::max();
36
37 //brute force to find closest red-blue pair
38 for(int i = 0; i < (int)redPoints.size(); ++i)
39 for(int j = 0; j < (int)bluePoints.size(); ++j)
40 minDistSq = std::min(minDistSq, minimizer.minimumOnObjectObject(redPoints[i], bluePoints[j]));
41 std::cout << "Brute force distance = " << sqrt(minDistSq) << ", calls = " << minimizer.calls << std::endl;
42
43 //using BVH to find closest red-blue pair
44 minimizer.calls = 0;
45 KdBVH<double, 2, Vector2d> redTree(redPoints.begin(), redPoints.end()), blueTree(bluePoints.begin(), bluePoints.end()); //construct the trees
46 minDistSq = BVMinimize(redTree, blueTree, minimizer); //actual BVH minimization call
47 std::cout << "BVH distance = " << sqrt(minDistSq) << ", calls = " << minimizer.calls << std::endl;
48
49 return 0;
50 }
51