70 lines
2.0 KiB
C++
70 lines
2.0 KiB
C++
#pragma once
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#include <list>
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#include <bits/stdc++.h> // For INT_MIN & INT_MAX
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#include "Point.h"
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#include "Line.h"
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class Quickhull
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{
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public:
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static void get_hull(std::list<Point> &input, std::list<Point> &output)
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{
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// Get leftmost and rightmost point
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Point leftmost(INT_MAX, 0), rightmost(INT_MIN, 0);
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for (const Point &point : input)
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{
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if (point.x() < leftmost.x()) {
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leftmost = point;
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} else if (point.y() > rightmost.y()) {
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rightmost = point;
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}
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}
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// Add them to the output
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output.emplace_back(leftmost);
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output.emplace_back(rightmost);
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// Remove them from the input (as well as duplicates)
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input.remove(leftmost);
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input.remove(rightmost);
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// Create a line from leftmost to rightmost
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Line line = Line(leftmost, rightmost);
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// Sort points between left and right of that line
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std::list<Point> points_left, points_right;
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for (const Point &point : input)
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{
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if (line.is_point_right(point))
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{
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points_right.emplace_back(point);
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}
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else
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{
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points_left.emplace_back(point);
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}
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}
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// Call get_hull_with_line with the left points, as well as with the right points, and the line
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get_hull_with_line(points_left, output, line);
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get_hull_with_line(points_right, output, line);
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}
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private:
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static void get_hull_with_line(std::list<Point> &input, std::list<Point> &output, const Line &line)
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{
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// If the input vector is empty, we're done
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if (input.empty()) return;
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// Find the point which is furthest away from the line, add it to the output
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// Build a triangle with these 3 points
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// Remove points inside this triangle
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// Recursively call get_hull_with_line for each side of the triangle
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}
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}; |