assimp/code/TargetAnimation.cpp

/*
Open Asset Import Library (assimp)
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All rights reserved.

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  following disclaimer.

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*/

#include "TargetAnimation.h"
#include <algorithm>
#include <assimp/ai_assert.h>

using namespace Assimp;


// ------------------------------------------------------------------------------------------------
KeyIterator::KeyIterator(const std::vector<aiVectorKey>* _objPos,
    const std::vector<aiVectorKey>* _targetObjPos,
    const aiVector3D*  defaultObjectPos /*= NULL*/,
    const aiVector3D*  defaultTargetPos /*= NULL*/)

        :   reachedEnd      (false)
        ,   curTime         (-1.)
        ,   objPos          (_objPos)
        ,   targetObjPos    (_targetObjPos)
        ,   nextObjPos      (0)
        ,   nextTargetObjPos(0)
{
    // Generate default transformation tracks if necessary
    if (!objPos || objPos->empty())
    {
        defaultObjPos.resize(1);
        defaultObjPos.front().mTime  = 10e10;

        if (defaultObjectPos)
            defaultObjPos.front().mValue = *defaultObjectPos;

        objPos = & defaultObjPos;
    }
    if (!targetObjPos || targetObjPos->empty())
    {
        defaultTargetObjPos.resize(1);
        defaultTargetObjPos.front().mTime  = 10e10;

        if (defaultTargetPos)
            defaultTargetObjPos.front().mValue = *defaultTargetPos;

        targetObjPos = & defaultTargetObjPos;
    }
}

// ------------------------------------------------------------------------------------------------
template <class T>
inline T Interpolate(const T& one, const T& two, ai_real val)
{
    return one + (two-one)*val;
}

// ------------------------------------------------------------------------------------------------
void KeyIterator::operator ++()
{
    // If we are already at the end of all keyframes, return
    if (reachedEnd) {
        return;
    }

    // Now search in all arrays for the time value closest
    // to our current position on the time line
    double d0,d1;

    d0 = objPos->at      ( std::min ( nextObjPos, static_cast<unsigned int>(objPos->size()-1))             ).mTime;
    d1 = targetObjPos->at( std::min ( nextTargetObjPos, static_cast<unsigned int>(targetObjPos->size()-1)) ).mTime;

    // Easiest case - all are identical. In this
    // case we don't need to interpolate so we can
    // return earlier
    if ( d0 == d1 )
    {
        curTime = d0;
        curPosition = objPos->at(nextObjPos).mValue;
        curTargetPosition = targetObjPos->at(nextTargetObjPos).mValue;

        // increment counters
        if (objPos->size() != nextObjPos-1)
            ++nextObjPos;

        if (targetObjPos->size() != nextTargetObjPos-1)
            ++nextTargetObjPos;
    }

    // An object position key is closest to us
    else if (d0 < d1)
    {
        curTime = d0;

        // interpolate the other
        if (1 == targetObjPos->size() || !nextTargetObjPos) {
            curTargetPosition = targetObjPos->at(0).mValue;
        }
        else
        {
            const aiVectorKey& last  = targetObjPos->at(nextTargetObjPos);
            const aiVectorKey& first = targetObjPos->at(nextTargetObjPos-1);

            curTargetPosition = Interpolate(first.mValue, last.mValue, (ai_real) (
                (curTime-first.mTime) / (last.mTime-first.mTime) ));
        }

        if (objPos->size() != nextObjPos-1)
            ++nextObjPos;
    }
    // A target position key is closest to us
    else
    {
        curTime = d1;

        // interpolate the other
        if (1 == objPos->size() || !nextObjPos) {
            curPosition = objPos->at(0).mValue;
        }
        else
        {
            const aiVectorKey& last  = objPos->at(nextObjPos);
            const aiVectorKey& first = objPos->at(nextObjPos-1);

            curPosition = Interpolate(first.mValue, last.mValue, (ai_real) (
                (curTime-first.mTime) / (last.mTime-first.mTime)));
        }

        if (targetObjPos->size() != nextTargetObjPos-1)
            ++nextTargetObjPos;
    }

    if (nextObjPos >= objPos->size()-1 &&
        nextTargetObjPos >= targetObjPos->size()-1)
    {
        // We reached the very last keyframe
        reachedEnd = true;
    }
}

// ------------------------------------------------------------------------------------------------
void TargetAnimationHelper::SetTargetAnimationChannel (
    const std::vector<aiVectorKey>* _targetPositions)
{
    ai_assert(NULL != _targetPositions);
    targetPositions = _targetPositions;
}

// ------------------------------------------------------------------------------------------------
void TargetAnimationHelper::SetMainAnimationChannel (
    const std::vector<aiVectorKey>* _objectPositions)
{
    ai_assert(NULL != _objectPositions);
    objectPositions = _objectPositions;
}

// ------------------------------------------------------------------------------------------------
void TargetAnimationHelper::SetFixedMainAnimationChannel(
    const aiVector3D& fixed)
{
    objectPositions = NULL; // just to avoid confusion
    fixedMain = fixed;
}

// ------------------------------------------------------------------------------------------------
void TargetAnimationHelper::Process(std::vector<aiVectorKey>* distanceTrack)
{
    ai_assert(NULL != targetPositions && NULL != distanceTrack);

    // TODO: in most cases we won't need the extra array
    std::vector<aiVectorKey>  real;

    std::vector<aiVectorKey>* fill = (distanceTrack == objectPositions ? &real : distanceTrack);
    fill->reserve(std::max( objectPositions->size(), targetPositions->size() ));

    // Iterate through all object keys and interpolate their values if necessary.
    // Then get the corresponding target position, compute the difference
    // vector between object and target position. Then compute a rotation matrix
    // that rotates the base vector of the object coordinate system at that time
    // to match the diff vector.

    KeyIterator iter(objectPositions,targetPositions,&fixedMain);
    for (;!iter.Finished();++iter)
    {
        const aiVector3D&  position  = iter.GetCurPosition();
        const aiVector3D&  tposition = iter.GetCurTargetPosition();

        // diff vector
        aiVector3D diff = tposition - position;
        ai_real f = diff.Length();

        // output distance vector
        if (f)
        {
            fill->push_back(aiVectorKey());
            aiVectorKey& v = fill->back();
            v.mTime  = iter.GetCurTime();
            v.mValue = diff;

            diff /= f;
        }
        else
        {
            // FIXME: handle this
        }

        // diff is now the vector in which our camera is pointing
    }

    if (real.size()) {
        *distanceTrack = real;
    }
}