/*

Open Asset Import Library (assimp)

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  following disclaimer.

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*/

/** @file Defines a helper class for the ASE and 3DS loaders to

 help them compute camera and spot light animation channels */

#ifndef AI_TARGET_ANIMATION_H_INC

#define AI_TARGET_ANIMATION_H_INC

#include <assimp/anim.h>

#include <vector>

namespace Assimp {

// ---------------------------------------------------------------------------

/** Helper class to iterate through all keys in an animation channel.

 *

 *  Missing tracks are interpolated. This is a helper class for

 *  TargetAnimationHelper, but it can be freely used for other purposes.

*/

class KeyIterator {

public:

    // ------------------------------------------------------------------

    /** Constructs a new key iterator

     *

     *  @param _objPos Object position track. May be nullptr.

     *  @param _targetObjPos Target object position track. May be nullptr.

     *  @param defaultObjectPos Default object position to be used if

     *    no animated track is available. May be nullptr.

     *  @param defaultTargetPos Default target position to be used if

     *    no animated track is available. May be nullptr.

     */

    KeyIterator(const std::vector<aiVectorKey> *_objPos,

            const std::vector<aiVectorKey> *_targetObjPos,

            const aiVector3D *defaultObjectPos = nullptr,

            const aiVector3D *defaultTargetPos = nullptr);

    // ------------------------------------------------------------------

    /** Returns true if all keys have been processed

     */

    bool Finished() const { return reachedEnd; }

    // ------------------------------------------------------------------

    /** Increment the iterator

     */

    void operator++();

    inline void operator++(int) { return ++(*this); }

    // ------------------------------------------------------------------

    /** Getters to retrieve the current state of the iterator

     */

    inline const aiVector3D &GetCurPosition() const { return curPosition; }

    inline const aiVector3D &GetCurTargetPosition() const { return curTargetPosition; }

    inline double GetCurTime() const { return curTime; }

private:

    //! Did we reach the end?

    bool reachedEnd;

    //! Represents the current position of the iterator

    aiVector3D curPosition, curTargetPosition;

    double curTime;

    //! Input tracks and the next key to process

    const std::vector<aiVectorKey> *objPos, *targetObjPos;

    unsigned int nextObjPos, nextTargetObjPos;

    std::vector<aiVectorKey> defaultObjPos, defaultTargetObjPos;

};

// ---------------------------------------------------------------------------

/** Helper class for the 3DS and ASE loaders to compute camera and spot light

 *  animations.

 *

 * 3DS and ASE store the differently to Assimp - there is an animation

 * channel for the camera/spot light itself and a separate position

 * animation channels specifying the position of the camera/spot light

 * look-at target */

class TargetAnimationHelper {

public:

    /// @brief The class constructor.

    TargetAnimationHelper() :

            targetPositions(nullptr),

            objectPositions(nullptr) {

        // empty

    }

    /// @brief The class destructor.

    ~TargetAnimationHelper() = default;

    // ------------------------------------------------------------------

    /** Sets the target animation channel

     *

     *  This channel specifies the position of the camera/spot light

     *  target at a specific position.

     *

     *  @param targetPositions Translation channel*/

    void SetTargetAnimationChannel(const std::vector<aiVectorKey> *targetPositions);

    // ------------------------------------------------------------------

    /** Sets the main animation channel

     *

     *  @param objectPositions Translation channel */

    void SetMainAnimationChannel(const std::vector<aiVectorKey> *objectPositions);

    // ------------------------------------------------------------------

    /** Sets the main animation channel to a fixed value

     *

     *  @param fixed Fixed value for the main animation channel*/

    void SetFixedMainAnimationChannel(const aiVector3D &fixed);

    // ------------------------------------------------------------------

    /** Computes final animation channels

     * @param distanceTrack Receive camera translation keys ... != nullptr. */

    void Process(std::vector<aiVectorKey> *distanceTrack);

private:

    const std::vector<aiVectorKey> *targetPositions, *objectPositions;

    aiVector3D fixedMain;

};

} // namespace Assimp

#endif // include guard