From c0fab0e941aecc92037eb4e3eed7987afbe4b620 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustav=20S=C3=B6rn=C3=A4s?= <gustav@sornas.net>
Date: Tue, 8 Dec 2020 10:21:25 +0100
Subject: impl l7

---
 labb7/src/fast.cpp | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 labb7/src/fast.cpp

(limited to 'labb7/src')

diff --git a/labb7/src/fast.cpp b/labb7/src/fast.cpp
new file mode 100644
index 0000000..ab7c7b5
--- /dev/null
+++ b/labb7/src/fast.cpp
@@ -0,0 +1,102 @@
+#include <QApplication>
+#include <QGraphicsView>
+#include <QGraphicsScene>
+#include <fstream>
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <chrono>
+#include <cmath>
+#include <unordered_map>
+#include "Point.h"
+
+// constants
+static const int SCENE_WIDTH = 512;
+static const int SCENE_HEIGHT = 512;
+
+void render_points(QGraphicsScene* scene, const vector<Point>& points) {
+    for(const auto& point : points) {
+        point.draw(scene);
+    }
+}
+
+void render_line(QGraphicsScene* scene, const Point& p1, const Point& p2) {
+    p1.lineTo(scene, p2);
+}
+
+int main(int argc, char *argv[]) {
+    QApplication a(argc, argv);
+
+    // open file
+    string filename = "grid4x4.txt";
+    ifstream input;
+    input.open(filename);
+
+    // the vector of points
+    vector<Point> points;
+
+    // read points from file
+    int N;
+    int x;
+    int y;
+
+    input >> N;
+
+    for (int i = 0; i < N; ++i) {
+        input >> x >> y;
+        points.push_back(Point(x, y));
+    }
+    input.close();
+
+    // setup graphical window
+    QGraphicsView *view = new QGraphicsView();
+    QGraphicsScene *scene = new QGraphicsScene(0, 0, SCENE_WIDTH, SCENE_HEIGHT);
+    view->setScene(scene);
+    // draw points to screen all at once
+    render_points(scene, points);
+    view->scale(1, -1); //screen y-axis is inverted
+    view->resize(view->sizeHint());
+    view->setWindowTitle("Fast Pattern Recognition");
+    view->show();
+
+    sort(points.begin(), points.end());
+    auto begin = chrono::high_resolution_clock::now();
+
+    vector<pair<double, Point>> angles;
+    for (int p1 = 0; p1 < N-1; p1++) {
+        angles.clear();
+        for (int p2 = p1 + 1; p2 < N; p2++) {
+            double angle = points.at(p1).slopeTo(points.at(p2));
+            angles.push_back({ angle, points.at(p2) });
+        }
+        sort(angles.begin(), angles.end());
+
+        cout << points.at(p1) << endl;
+
+        double prev_angle = angles[0].first;
+        int num_in_row = 0;
+        for (int i = 1; i < angles.size(); i++) {
+            if (angles[i].first == prev_angle) {
+                num_in_row++;
+                if (num_in_row >= 2) {
+                    render_line(scene, points.at(p1), angles[i].second);
+                }
+            } else {
+                num_in_row = 0;
+            }
+            cout << i << " " << num_in_row << " " << angles[i].first << " " << angles[i].second << endl;
+            prev_angle = angles[i].first;
+        }
+        if (num_in_row >= 2) {
+            render_line(scene, points.at(p1), angles[angles.size() - 1].second);
+        }
+        cout << endl;
+    }
+
+    auto end = chrono::high_resolution_clock::now();
+    cout << "Computing line segments took "
+         << std::chrono::duration_cast<chrono::milliseconds>(end - begin).count()
+         << " milliseconds." << endl;
+
+    return a.exec(); // start Qt event loop
+}
-- 
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