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2 changed files with 0 additions and 121 deletions

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@ -8,6 +8,5 @@ AllowShortLambdasOnASingleLine: Inline
AllowShortLoopsOnASingleLine: 'false'
AlwaysBreakBeforeMultilineStrings: 'true'
IndentWidth: '4'
ColumnLimit: 100
...

120
kdtree.h
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@ -1,120 +0,0 @@
#include <algorithm>
#include <glm/glm.hpp>
#include <string>
#include <vector>
// Forward declarations
struct Node;
struct Point;
struct Triangle;
struct Node {
Node(int axis, Point *point, Node *left, Node *right)
: axis(axis), point(point), left(left), right(right) {}
int axis;
Point *point;
Node *left;
Node *right;
};
struct Triangle {
Triangle(Point *p1, Point *p2, Point *p3) : p1(p1), p2(p2), p3(p3) {}
Point *p1;
Point *p2;
Point *p3;
};
struct Point {
Point(float coordinates[3], Triangle *triangle)
: coordinates(coordinates), triangle(triangle) {}
float *coordinates;
Triangle *triangle;
};
class KDTree {
public:
KDTree(std::vector<Point *> points) { root = build(points, 0); }
~KDTree() = default;
std::string to_string() {
std::string str = "";
to_string_recurse(str, root, 0);
return str;
}
private:
Node *root;
int MAX_DEPTH = 500;
// Returns a comparator lambda for assessing which of the two points has a
// greater coordinate in the given axis.
auto get_point_comparator(int axis) {
return [axis](Point *p1, Point *p2) {
return p1->coordinates[axis] < p2->coordinates[axis];
};
}
Node *build(std::vector<Point *> points, int depth) {
// Exit conditions
if (points.empty() || depth > MAX_DEPTH) { return nullptr; }
// Select axis by choosing the one with maximal extent
float max_extent = 0;
int axis = 0;
for (int it_axis = 0; it_axis < 3; it_axis++) {
// Get extent along this axis
auto comparator = get_point_comparator(it_axis);
Point *min = *std::max_element(points.begin(), points.end(), comparator);
Point *max = *std::max_element(points.begin(), points.end(), comparator);
float extent = max->coordinates[it_axis] - min->coordinates[it_axis];
// Is it greater than max_extent?
if (extent > max_extent) {
// If so, make this the splitting axis
max_extent = extent;
axis = it_axis;
}
}
// Choose the median as the pivot and sort the points into
// left-of-median and right-of-median using nth_element
int middle = points.size() / 2;
std::nth_element(points.begin(), points.begin() + middle, points.end(),
get_point_comparator(axis));
Point *median = points[middle];
// TODO: This copies. Can we split the vector into two without copying?
std::vector<Point *> left_of_median(points.begin(), points.begin() + middle);
std::vector<Point *> right_of_median(points.begin() + middle, points.end());
// Create node, recursively call to construct subtree
return new Node(axis, median, build(left_of_median, depth + 1),
build(right_of_median, depth + 1));
}
void to_string_recurse(std::string &str, Node *node, int depth) {
if (node == nullptr) { return; }
Point *point = node->point;
str += std::string(depth, '-') + std::to_string(point->coordinates[0]) + ", " +
std::to_string(point->coordinates[1]) + ", " +
std::to_string(point->coordinates[2]) + "\n";
to_string_recurse(str, node->left, depth + 1);
to_string_recurse(str, node->right, depth + 1);
}
};