Tween.h

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#pragma once
 
#include <string>
#include <unordered_map>
#include <vector>
 
namespace eve::animation {
 
class Animation;
 
class Tween {
public:
    explicit Tween(float duration = 1.f);
    ~Tween();
 
    Tween(const Tween &)            = delete;
    Tween &operator=(const Tween &) = delete;
 
    void setFrom(const std::string &name, float value);
    void setTo(const std::string &name, float value);
    void setDelta(const std::string &name, float delta);
 
    void setFromAngle(const std::string &name, float radians);
    void setToAngle(const std::string &name, float radians);
    void setDeltaAngle(const std::string &name, float deltaRadians);
 
    bool  has(const std::string &name) const;
    float get(const std::string &name) const;
    float getFrom(const std::string &name) const;
    float getTo(const std::string &name) const;
    float getDelta(const std::string &name) const;
 
    void        setDuration(float seconds);
    float       getDuration() const { return duration_; }
    void        setDelay(float seconds);
    float       getDelay() const { return delay_; }
    void        setEase(const std::string &kind);
    std::string getEase() const { return ease_; }
 
    void setRepeat(int count);
    int  getRepeat() const { return repeat_; }
    void setYoyo(bool enabled) { yoyo_ = enabled; }
    bool getYoyo() const { return yoyo_; }
 
    void start();
    void pause();
    void resume();
    void stop();
    void reset();
 
    bool isRunning() const { return state_ == State::Running; }
    bool isPaused() const { return state_ == State::Paused; }
    bool isFinished() const { return state_ == State::Finished; }
    bool isStopped() const { return state_ == State::Idle || state_ == State::Stopped; }
    bool isDelayed() const { return state_ == State::Delayed; }
    bool isActive() const {
        return state_ == State::Delayed || state_ == State::Running || state_ == State::Paused;
    }
 
    float getElapsed() const { return elapsed_; }
    float getProgress() const;
    float getEasedProgress() const;
 
    bool update(float dt);
 
    float evaluate(const std::string &name, float t) const;
 
    int         getPropertyCount() const { return static_cast<int>(order_.size()); }
    std::string getPropertyName(int index) const;
 
private:
    friend class Animation;
 
    enum class State { Idle, Delayed, Running, Paused, Finished, Stopped };
 
    enum class EndMode { Absolute, Delta };
 
    struct Track {
        float   from     = 0.f;
        float   to       = 0.f;
        float   delta    = 0.f;
        float   current  = 0.f;
        bool    hasFrom  = false;
        EndMode endMode  = EndMode::Absolute;
        bool    isAngle  = false;
        bool    resolved = false;
    };
 
    void          setOwner(Animation *owner) { owner_ = owner; }
    Animation    *owner() const { return owner_; }
    Track        &ensureTrack(const std::string &name);
    const Track  *findTrack(const std::string &name) const;
    void          resolveTracks();
    void          applyProgress(float linearT);
    void          finishCycle();
    static float  ease(float t, const std::string &kind);
    static float  lerpAngle(float a, float b, float t);
    static float  clamp01(float t);
 
    Animation                              *owner_    = nullptr;
    float                                   duration_ = 1.f;
    float                                   delay_    = 0.f;
    float                                   delayLeft_ = 0.f;
    float                                   elapsed_  = 0.f;
    int                                     repeat_   = 1;
    int                                     played_   = 0;
    bool                                    yoyo_     = false;
    bool                                    reverse_  = false;
    std::string                             ease_     = "linear";
    State                                   state_    = State::Idle;
    std::unordered_map<std::string, Track>  tracks_;
    std::vector<std::string>                order_;
};
 
}  // namespace eve::animation