added double jump and sitting state

term1/seminar09_libraries/04_n_bodies/balls.cpp

@@ -0,0 +1,89 @@
+#include <SFML/Graphics.hpp>
+#include <iostream>
+#include <vector>
+#include <cstdlib>
+#include <ctime>
+#include <cmath>
+
+using namespace std;
+
+const int min_distance = 5;
+const float G = 500;
+
+struct Ball
+{
+    float radius;
+    float mass = 1;
+    sf::Vector2f position;
+    sf::Vector2f velocity;
+};
+
+
+int main()
+{
+    srand(time(0));
+    
+    const int width = 1000;
+    const int height = 800;
+    const int n_balls = 15;
+
+    // Шаг по времени
+    const float delta_t = 0.1;
+    sf::RenderWindow window(sf::VideoMode(width, height), "My window");
+    window.setFramerateLimit(60);
+    sf::CircleShape circle(50.0f);
+    circle.setFillColor({200, 216, 200});
+    std::vector<Ball> balls;
+    balls.resize(n_balls);
+    for (int i = 0; i < n_balls; i++)
+    {
+        balls[i].radius = 4 + rand() % 8;
+        balls[i].position = {(float)(rand() % width), (float)(rand() % height)};
+        balls[i].velocity = {(float)(rand() % 100 - 50), (float)(rand() % 100 - 50)};
+    }
+    while (window.isOpen())
+    {
+        sf::Event event;
+        while (window.pollEvent(event))
+        {
+            if (event.type == sf::Event::Closed)
+                window.close();
+        }
+
+        window.clear(sf::Color::Black);
+
+        for (int i = 0; i < n_balls; i++)
+        {
+            
+            balls[i].position += balls[i].velocity * delta_t;
+            for (int j = 0; j < n_balls; ++j) {
+                if (i == j)
+                        continue;
+                float distance = std::sqrt((balls[j].position.x - balls[i].position.x) * (balls[j].position.x - balls[i].position.x) + (balls[j].position.y - balls[i].position.y) * (balls[j].position.y - balls[i].position.y)); 
+                if (distance < min_distance)
+                        continue;
+                auto direction = balls[j].position - balls[i].position;
+                balls[i].velocity += (direction * G * delta_t * balls[j].mass) / (distance * distance);
+                }
+            
+            if (((balls[i].position.x - balls[i].radius) < 0) || (balls[i].position.x + balls[i].radius> width)) {
+                balls[i].velocity.x = -balls[i].velocity.x;
+                balls[i].position.x = (balls[i].position.x - balls[i].radius < 0 ? balls[i].radius : width - balls[i].radius);
+            }
+            if ((balls[i].position.y - balls[i].radius < 0) || (balls[i].position.y + balls[i].radius > height)) {
+                balls[i].velocity.y = -balls[i].velocity.y;
+                balls[i].position.y = (balls[i].position.y - balls[i].radius < 0 ? balls[i].radius : height - balls[i].radius);
+            }
+
+            circle.setRadius(balls[i].radius);
+            circle.setOrigin(balls[i].radius, balls[i].radius);
+            circle.setPosition(balls[i].position);
+            
+            window.draw(circle);
+        }
+
+        window.display();
+    }
+
+    return 0;
+}