particles.h

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#ifndef ASW_PARTICLES_H
#define ASW_PARTICLES_H
 
#include <vector>
 
#include "./color.h"
#include "./game.h"
#include "./geometry.h"
#include "./types.h"
 
namespace asw {
 
  struct ParticleConfig {
    // Lifetime in seconds
    float lifetimeMin{1.0F};
    float lifetimeMax{2.0F};
 
    // Speed in pixels per second
    float speedMin{50.0F};
    float speedMax{100.0F};
 
    // Direction (radians)
    float angleMin{0.0F};
    float angleMax{6.2832F};  // Full circle
 
    // Visual
    Color colorStart{255, 255, 255, 255};
    Color colorEnd{255, 255, 255, 0};
    float alphaStart{1.0F};
    float alphaEnd{0.0F};
    float sizeStart{4.0F};
    float sizeEnd{1.0F};
 
    // Physics in pixels per second squared
    Vec2<float> gravity{0.0F, 0.0F};
 
    // Optional texture (nullptr = use circleFill)
    Texture texture{nullptr};
  };
 
  class ParticleEmitter : public game::GameObject {
   public:
    ParticleEmitter() = default;
 
    explicit ParticleEmitter(const ParticleConfig& config,
                             int maxParticles = 256);
 
    void setEmissionRate(float rate);
 
    void emit(int count);
 
    void start();
 
    void stop();
 
    void update(float deltaTime) override;
 
    void draw() override;
 
    int getAliveCount() const;
 
   private:
    struct Particle {
      Vec2<float> position;
      Vec2<float> velocity;
      float lifetime{0.0F};
      float age{0.0F};
      float size{0.0F};
      float rotation{0.0F};
      bool alive{false};
    };
 
    void spawnParticle();
 
    ParticleConfig config;
    std::vector<Particle> particles;
    int aliveCount{0};
 
    // Emission rate in particles per second
    float emissionRate{0.0F};
    float emissionAccumulator{0.0F};
    bool emitting{false};
  };
 
}  // namespace asw
 
#endif  // ASW_PARTICLES_H