Added wall bouncing logic (flawed); added bounding box computation and display

polygons.cc

@@ -1,22 +1,28 @@
 #include "polygons.h"
 
+#include "cairo.h"
+#include "game.h"
 #include "matrix.h"
 #include "polygon_generator.h"
 
-#include <cmath>
 #include <iostream>
 
 polygon* polygons = nullptr;
-uint n_polygons = 3;
+uint n_polygons = 1;
 
 void polygons_init_state() {
     polygons = new polygon[n_polygons];
 
+    std::cout << "width" << width << std::endl;
+    // polygons[0] = poly_generate::square(200)
+    //                   .set_center({400, 600})
+    //                   .set_angle(37)
+    //                   .set_speed({1, -1});
     polygons[0] = poly_generate::triangle(150, 150, 30)
                       .set_center({400, 300})
-                      .set_angle(90);
-    polygons[1] = poly_generate::square(200).set_center({200, 600});
-    polygons[2] = poly_generate::rectangle(200, 100).set_center({600, 600});
+                      .set_angle(45)
+                      .set_speed({3, 2});
+    // polygons[2] = poly_generate::rectangle(200, 100).set_center({600, 600});
 }
 
 static double to_rad(double angle_in_deg) {
@@ -24,31 +30,63 @@ static double to_rad(double angle_in_deg) {
     return angle_in_deg * PI_180;
 }
 
+static void check_border_collision(polygon* p) {
+    for (auto& point : p->global_points) {
+        if (point.x <= 0 || point.x >= width) {
+            p->speed.x *= -1;
+            break;
+        }
+        if (point.y <= 0 || point.y >= height) {
+            p->speed.y *= -1;
+            break;
+        }
+    }
+}
+
 void polygons_update_state() {
-    static double angle = 0;
     for (polygon* p = polygons; p != polygons + n_polygons; ++p) {
         p->rotate(1);
-        p->translate({2 * std::cos(angle), 0});
+        check_border_collision(p);
+        p->translate(p->speed);
     }
-    angle -= .03;
 }
 
-void polygon::draw(cairo_t* cr) const {
-    const vec2d& center = this->center;
-    cairo_set_source_rgb(cr, 1, 1, 1);
-
+void polygon::update_global_points() {
     double cos_theta = std::cos(to_rad(this->angle));
     double sin_theta = std::sin(to_rad(this->angle));
 
     matrix rotation = matrix{{cos_theta, sin_theta}, {-sin_theta, cos_theta}};
 
-    vec2d final_point;
-    for (auto& point : this->points) {
-        final_point = rotation * point;
-        cairo_line_to(cr, center.x + final_point.x, center.y + final_point.y);
+    for (uint i = 0; i < this->points.size(); ++i)
+        this->global_points[i] = rotation * this->points[i] + this->center;
 }
-    final_point = rotation * this->points[0];
-    cairo_line_to(cr, center.x + final_point.x, center.y + final_point.y);
+
+void polygon::draw_bounding_rect(cairo_t* cr) const {
+    cairo_set_source_rgb(cr, .7, .7, .7);
+    double dashes[] = {5, 10};
+    cairo_set_dash(cr, dashes, 2, 0);
+
+    auto bb = this->get_bounding_box();
+    vec2d min = bb.first, max = bb.second;
+
+    cairo_line_to(cr, min.x, min.y);
+    cairo_line_to(cr, min.x, max.y);
+    cairo_line_to(cr, max.x, max.y);
+    cairo_line_to(cr, max.x, min.y);
+    cairo_line_to(cr, min.x, min.y);
+    cairo_stroke(cr);
+    cairo_set_dash(cr, 0, 0, 0); // disable dashes
+}
+
+void polygon::draw(cairo_t* cr) const {
+    this->draw_bounding_rect(cr);
+
+    cairo_set_source_rgb(cr, 1, 1, 1);
+
+    for (auto& point : this->global_points)
+        cairo_line_to(cr, point.x, point.y);
+
+    cairo_line_to(cr, this->global_points[0].x, this->global_points[0].y);
     cairo_stroke(cr);
 }
 

polygons.h

@@ -3,34 +3,74 @@
 
 #include "vec2d.h"
 
+#include <cmath>
 #include <gtk/gtk.h>
+#include <utility>
 #include <vector>
 
 class polygon {
+  private:
+    void update_global_points();
+
   public:
     vec2d center;
     double angle;
     std::vector<vec2d> points;
+    std::vector<vec2d> global_points = points;
+
+    vec2d speed, angular_speed;
 
     void draw(cairo_t* cr) const;
+    void draw_bounding_rect(cairo_t* cr) const;
+
+    std::pair<vec2d, vec2d> get_bounding_box() const {
+        vec2d min{INFINITY, INFINITY}, max{-INFINITY, -INFINITY};
+
+        for (auto& point : this->global_points) {
+            if (point.x < min.x)
+                min.x = point.x;
+            if (point.y < min.y)
+                min.y = point.y;
+
+            if (point.x > max.x)
+                max.x = point.x;
+            if (point.y > max.y)
+                max.y = point.y;
+        }
+        return {min, max};
+    }
 
     polygon& set_center(vec2d c) {
         center = c;
+        update_global_points();
+        return *this;
+    }
+
+    polygon& set_speed(vec2d s) {
+        speed = s;
+        return *this;
+    }
+
+    polygon& set_angular_speed(vec2d as) {
+        angular_speed = as;
         return *this;
     }
 
     polygon& set_angle(double a) {
         angle = a;
+        update_global_points();
         return *this;
     }
 
     polygon& translate(vec2d delta) {
         center += delta;
+        update_global_points();
         return *this;
     }
 
     polygon& rotate(double delta) {
         angle += delta;
+        update_global_points();
         return *this;
     }
 };