less trivial C++ interop

Sources/CppBackend/CMakeLists.txt

@@ -1,4 +1,4 @@
-add_library(CppBackend STATIC backend.h backend.cpp)
+add_library(CppBackend STATIC ball.hpp ball.cpp)
 set_property(TARGET CppBackend PROPERTY Swift_MODULE_NAME "CppBackend")
 set_property(TARGET CppBackend PROPERTY CXX_STANDARD 20)
 

Sources/CppBackend/backend.cpp

@@ -1,7 +0,0 @@
-#include "backend.h"
-
-#include <iostream>
-
-void backend_init() {
-  std::cout << "Hello World" << std::endl;
-}

Sources/CppBackend/backend.h

@@ -1,3 +0,0 @@
-#pragma once
-
-void backend_init();

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);
+  }
+}

Sources/CppBackend/ball.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <simd/simd.h>
+#include <vector>
+
+struct Ball {
+  using vec2f = simd::float2;
+
+private:
+  constexpr static float speed = 80.0f;
+  constexpr static float worldSize = 512.0f;
+
+  vec2f _position, _velocity;
+  float _size;
+
+public:
+  Ball(vec2f pos, float angle, float ballSize) noexcept;
+  virtual ~Ball() noexcept = default;
+
+  void update(float deltaTime) noexcept;
+
+  [[nodiscard]] constexpr const vec2f& position() const noexcept {
+    return _position;
+  }
+  [[nodiscard]] constexpr const vec2f& velocity() const noexcept {
+    return _velocity;
+  }
+  [[nodiscard]] constexpr const float size() const noexcept {
+    return _size;
+  }
+};
+
+
+struct BallWorld {
+  std::vector<Ball> balls;
+
+  void add(Ball::vec2f pos, float angle, float ballSize) noexcept;
+  void update(float deltaTime) noexcept;
+};

Sources/CppBackend/module.modulemap

@@ -1,3 +1,3 @@
 module CppBackend {
-  header "backend.h"
+  header "ball.hpp"
 }