particles.h

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#ifndef ASW_PARTICLES_H
#define ASW_PARTICLES_H
 
#include <vector>
 
#include "./camera.h"
#include "./color.h"
#include "./game.h"
#include "./geometry.h"
#include "./types.h"
 
namespace asw {
 
struct ParticleConfig {
    // Lifetime in seconds
    float lifetime_min { 1.0F };
    float lifetime_max { 2.0F };
 
    // Speed in pixels per second
    float speed_min { 50.0F };
    float speed_max { 100.0F };
 
    // Direction (radians)
    float angle_min { 0.0F };
    float angle_max { 6.2832F }; // Full circle
 
    // Visual
    Color color_start { 255, 255, 255, 255 };
    Color color_end { 255, 255, 255, 0 };
    float alpha_start { 1.0F };
    float alpha_end { 0.0F };
    float size_start { 4.0F };
    float size_end { 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, uint32_t maxParticles = 256);
 
    void set_emission_rate(float rate);
 
    void emit(uint32_t count);
 
    void start();
 
    void stop();
 
    void update(float dt) override;
 
    void draw() override;
 
    void draw(const Camera& camera);
 
    uint32_t get_alive_count() const;
 
private:
    void draw_offset(const Vec2<float>& offset);
 
    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 spawn_particle();
 
    ParticleConfig config;
    std::vector<Particle> particles;
    uint32_t alive_count { 0 };
 
    // Emission rate in particles per second
    float emission_rate { 0.0F };
    float emission_accumulator { 0.0F };
    bool emitting { false };
};
 
} // namespace asw
 
#endif // ASW_PARTICLES_H