feat: basic game structure w/ Ball physics & input handling

src/Ball.cpp

@@ -0,0 +1,57 @@
+#include "Ball.hpp"
+
+#include <cmath>
+
+#include "Constants.hpp"
+
+Ball::Ball(float radius, const sf::Vector2f& pos, const sf::Vector2f& vel)
+    : m_radius(radius), m_velocity(vel) {
+    m_shape.setRadius(radius);
+    m_shape.setOrigin(sf::Vector2f(radius, radius));
+    m_shape.setPosition(pos);
+    m_shape.setFillColor(sf::Color::Red);
+}
+
+void Ball::update(float dt) {
+    m_velocity.y += Constants::GRAVITY * dt;
+    m_shape.move(m_velocity * dt);
+    handleWallCollision();
+}
+
+void Ball::draw(sf::RenderWindow& window) { window.draw(m_shape); }
+
+void Ball::applyImpulse(const sf::Vector2f& impulse) { m_velocity += impulse; }
+
+sf::Vector2f Ball::getPosition() const { return m_shape.getPosition(); }
+
+void Ball::handleWallCollision() {
+    sf::Vector2f pos = m_shape.getPosition();
+
+    auto handleAxis = [&](int axis, float min, float max, float& velocity,
+                          float radius, float restitution) {
+        float value = (axis == 0) ? pos.x : pos.y;
+
+        if (value - radius < min) {
+            value = min + radius;
+            velocity = -velocity * restitution;
+        } else if (value + radius > max) {
+            value = max - radius;
+            velocity = -velocity * restitution;
+            if (axis == 1 && std::abs(velocity) < 10.f) velocity = 0.f;
+        }
+
+        (axis == 0 ? pos.x : pos.y) = value;
+    };
+
+    handleAxis(0, 0.f, Constants::WIDTH, m_velocity.x, m_radius,
+               Constants::RESTITUTION);
+    handleAxis(1, 0.f, Constants::HEIGHT, m_velocity.y, m_radius,
+               Constants::RESTITUTION);
+
+    if (pos.y + m_radius >= Constants::HEIGHT - 1.0f) {
+        m_velocity.x *= Constants::FRICTION;
+        if (std::abs(m_velocity.x) < 5.f) m_velocity.x = 0.f;
+    }
+
+    m_shape.setPosition(pos);
+}