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#pragma once
#ifndef AV_ANIMEVALUATOR_H_INCLUDED
#define AV_ANIMEVALUATOR_H_INCLUDED

/** Calculates a pose for a given time of an animation */

#include <tuple>
#include <vector>
#include <assimp/matrix4x4.h>

struct aiAnimation;

namespace AssimpView {

/**
 *  @brief  Calculates transformations for a given timestamp from a set of animation tracks. Not directly useful,
 *          better use the AnimPlayer class.
 */
class AnimEvaluator {
public:
    /// @brief  Constructor on a given animation. The animation is fixed throughout the lifetime of
    /// the object.
    /// @param pAnim    The animation to calculate poses for. Ownership of the animation object stays
    ///                 at the caller, the evaluator just keeps a reference to it as long as it persists.
    AnimEvaluator(const aiAnimation *pAnim);

    /// @brief  The class destructor.
    ~AnimEvaluator() = default;

    /// @brief Evaluates the animation tracks for a given time stamp.
    /// The calculated pose can be retrieved as an array of transformation
    /// matrices afterwards by calling GetTransformations().
    /// @param pTime    The time for which you want to evaluate the animation, in seconds.
    ///                 Will be mapped into the animation cycle, so it can get an arbitrary
    ///                 value. Best use with ever-increasing time stamps.
    void Evaluate(double pTime);

    /// @brief  Returns the transform matrices calculated at the last Evaluate() call.
    ///         The array matches the mChannels array of the aiAnimation.
    const std::vector<aiMatrix4x4> &GetTransformations() const { return mTransforms; }

private:
    const aiAnimation *mAnim;
    double mLastTime;
    std::vector<std::tuple<unsigned int, unsigned int, unsigned int>> mLastPositions;
    std::vector<aiMatrix4x4> mTransforms;
};

} // end of namespace AssimpView

#endif // AV_ANIMEVALUATOR_H_INCLUDED