less trivial C++ interop

Sources/CppBackend/ball.cpp

@@ -0,0 +1,41 @@
+#include "ball.hpp"
+#include <cmath>
+
+
+Ball::Ball(vec2f pos, float angle, float ballSize) noexcept :
+  _position(pos),
+  _velocity(simd::make<vec2f>(
+     std::cos(angle * M_PI * 2.0f),
+    -std::sin(angle * M_PI * 2.0f)
+  )),
+  _size(ballSize) {
+}
+
+void Ball::update(float deltaTime) noexcept {
+  _position += _velocity * speed * deltaTime;
+  if (_position.x < _size) {
+    _velocity.x = -_velocity.x;
+    _position.x = _size;
+  } else if (_position.x > worldSize - _size) {
+    _velocity.x = -_velocity.x;
+    _position.x = worldSize - _size;
+  }
+  if (_position.y < _size) {
+    _velocity.y = -_velocity.y;
+    _position.y = _size;
+  } else if (_position.y > worldSize - _size) {
+    _velocity.y = -_velocity.y;
+    _position.y = worldSize - _size;
+  }
+}
+
+
+void BallWorld::add(Ball::vec2f pos, float angle, float ballSize) noexcept {
+  balls.emplace_back(Ball{ pos, angle, ballSize });
+}
+
+void BallWorld::update(float deltaTime) noexcept {
+  for (auto& ball : balls) {
+    ball.update(deltaTime);
+  }
+}