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/** @file  LWOAnimation.cpp
 *  @brief LWOAnimationResolver utility class
 *
 *  It's a very generic implementation of LightWave's system of
 *  component-wise-animated stuff. The one and only fully free
 *  implementation of LightWave envelopes of which I know.
*/

#if (!defined ASSIMP_BUILD_NO_LWO_IMPORTER) && (!defined ASSIMP_BUILD_NO_LWS_IMPORTER)

#include <functional>

// internal headers
#include "LWOFileData.h"
#include <assimp/anim.h>

using namespace Assimp;
using namespace Assimp::LWO;

// ------------------------------------------------------------------------------------------------
// Construct an animation resolver from a given list of envelopes
AnimResolver::AnimResolver(std::list<Envelope> &_envelopes, double tick) :
        envelopes(_envelopes),
        sample_rate(0.),
        envl_x(),
        envl_y(),
        envl_z(),
        end_x(),
        end_y(),
        end_z(),
        flags(),
        sample_delta() {
    trans_x = trans_y = trans_z = nullptr;
    rotat_x = rotat_y = rotat_z = nullptr;
    scale_x = scale_y = scale_z = nullptr;

    first = last = 150392.;

    // find transformation envelopes
    for (std::list<LWO::Envelope>::iterator it = envelopes.begin(); it != envelopes.end(); ++it) {

        (*it).old_first = 0;
        (*it).old_last = (*it).keys.size() - 1;

        if ((*it).keys.empty()) {
            continue;
        }
        if ((int)(*it).type < 1 || (int)(*it).type>EnvelopeType_Unknown) {
            continue;
        }
        switch ((*it).type) {
        // translation
        case LWO::EnvelopeType_Position_X:
            trans_x = &*it;
            break;
        case LWO::EnvelopeType_Position_Y:
            trans_y = &*it;
            break;
        case LWO::EnvelopeType_Position_Z:
            trans_z = &*it;
            break;

            // rotation
        case LWO::EnvelopeType_Rotation_Heading:
            rotat_x = &*it;
            break;
        case LWO::EnvelopeType_Rotation_Pitch:
            rotat_y = &*it;
            break;
        case LWO::EnvelopeType_Rotation_Bank:
            rotat_z = &*it;
            break;

            // scaling
        case LWO::EnvelopeType_Scaling_X:
            scale_x = &*it;
            break;
        case LWO::EnvelopeType_Scaling_Y:
            scale_y = &*it;
            break;
        case LWO::EnvelopeType_Scaling_Z:
            scale_z = &*it;
            break;
        default:
            continue;
        };

        // convert from seconds to ticks
        for (std::vector<LWO::Key>::iterator d = (*it).keys.begin(); d != (*it).keys.end(); ++d)
            (*d).time *= tick;

        // set default animation range (minimum and maximum time value for which we have a keyframe)
        first = std::min(first, (*it).keys.front().time);
        last = std::max(last, (*it).keys.back().time);
    }

    // deferred setup of animation range to increase performance.
    // typically the application will want to specify its own.
    need_to_setup = true;
}

// ------------------------------------------------------------------------------------------------
// Reset all envelopes to their original contents
void AnimResolver::ClearAnimRangeSetup() {
    for (std::list<LWO::Envelope>::iterator it = envelopes.begin(); it != envelopes.end(); ++it) {

        (*it).keys.erase((*it).keys.begin(), (*it).keys.begin() + (*it).old_first);
        (*it).keys.erase((*it).keys.begin() + (*it).old_last + 1, (*it).keys.end());
    }
}

// ------------------------------------------------------------------------------------------------
// Insert additional keys to match LWO's pre& post behaviors.
void AnimResolver::UpdateAnimRangeSetup() {
    // XXX doesn't work yet (hangs if more than one envelope channels needs to be interpolated)

    for (std::list<LWO::Envelope>::iterator it = envelopes.begin(); it != envelopes.end(); ++it) {
        if ((*it).keys.empty()) continue;

        const double my_first = (*it).keys.front().time;
        const double my_last = (*it).keys.back().time;

        const double delta = my_last - my_first;
        if (delta == 0.0) {
            continue;
        }

        const size_t old_size = (*it).keys.size();
        const float value_delta = (*it).keys.back().value - (*it).keys.front().value;

        // NOTE: We won't handle reset, linear and constant here.
        // See DoInterpolation() for their implementation.

        // process pre behavior
        switch ((*it).pre) {
        case LWO::PrePostBehaviour_OffsetRepeat:
        case LWO::PrePostBehaviour_Repeat:
        case LWO::PrePostBehaviour_Oscillate: {
            const double start_time = delta - std::fmod(my_first - first, delta);
            std::vector<LWO::Key>::iterator n = std::find_if((*it).keys.begin(), (*it).keys.end(),
                                                    [start_time](double t) { return start_time > t; }), m;

            size_t ofs = 0;
            if (n != (*it).keys.end()) {
                // copy from here - don't use iterators, insert() would invalidate them
                ofs = (*it).keys.end() - n;
                (*it).keys.insert((*it).keys.begin(), ofs, LWO::Key());

                std::copy((*it).keys.end() - ofs, (*it).keys.end(), (*it).keys.begin());
            }

            // do full copies. again, no iterators
            const unsigned int num = (unsigned int)((my_first - first) / delta);
            (*it).keys.resize((*it).keys.size() + num * old_size);

            n = (*it).keys.begin() + ofs;
            bool reverse = false;
            for (unsigned int i = 0; i < num; ++i) {
                m = n + old_size * (i + 1);
                std::copy(n, n + old_size, m);
                const bool res = ((*it).pre == LWO::PrePostBehaviour_Oscillate);
                reverse = !reverse;
                if (res && reverse) {
                    std::reverse(m, m + old_size - 1);
                }
            }

            // update time values
            n = (*it).keys.end() - (old_size + 1);
            double cur_minus = delta;
            unsigned int tt = 1;
            for (const double tmp = delta * (num + 1); cur_minus <= tmp; cur_minus += delta, ++tt) {
                m = (delta == tmp ? (*it).keys.begin() : n - (old_size + 1));
                for (; m != n; --n) {
                    (*n).time -= cur_minus;

                    // offset repeat? add delta offset to key value
                    if ((*it).pre == LWO::PrePostBehaviour_OffsetRepeat) {
                        (*n).value += tt * value_delta;
                    }
                }
            }
            break;
        }
        default:
            // silence compiler warning
            break;
        }

        // process post behavior
        switch ((*it).post) {

        case LWO::PrePostBehaviour_OffsetRepeat:
        case LWO::PrePostBehaviour_Repeat:
        case LWO::PrePostBehaviour_Oscillate:

            break;

        default:
            // silence compiler warning
            break;
        }
    }
}

// ------------------------------------------------------------------------------------------------
// Extract bind pose matrix
void AnimResolver::ExtractBindPose(aiMatrix4x4 &out) {
    // If we have no envelopes, return identity
    if (envelopes.empty()) {
        out = aiMatrix4x4();
        return;
    }
    aiVector3D angles, scaling(1.f, 1.f, 1.f), translation;

    if (trans_x) translation.x = trans_x->keys[0].value;
    if (trans_y) translation.y = trans_y->keys[0].value;
    if (trans_z) translation.z = trans_z->keys[0].value;

    if (rotat_x) angles.x = rotat_x->keys[0].value;
    if (rotat_y) angles.y = rotat_y->keys[0].value;
    if (rotat_z) angles.z = rotat_z->keys[0].value;

    if (scale_x) scaling.x = scale_x->keys[0].value;
    if (scale_y) scaling.y = scale_y->keys[0].value;
    if (scale_z) scaling.z = scale_z->keys[0].value;

    // build the final matrix
    aiMatrix4x4 s, rx, ry, rz, t;
    aiMatrix4x4::RotationZ(angles.z, rz);
    aiMatrix4x4::RotationX(angles.y, rx);
    aiMatrix4x4::RotationY(angles.x, ry);
    aiMatrix4x4::Translation(translation, t);
    aiMatrix4x4::Scaling(scaling, s);
    out = t * ry * rx * rz * s;
}

// ------------------------------------------------------------------------------------------------
// Do a single interpolation on a channel
void AnimResolver::DoInterpolation(std::vector<LWO::Key>::const_iterator cur,
        LWO::Envelope *envl, double time, float &fill) {
    if (envl->keys.size() == 1) {
        fill = envl->keys[0].value;
        return;
    }

    // check whether we're at the beginning of the animation track
    if (cur == envl->keys.begin()) {

        // ok ... this depends on pre behaviour now
        // we don't need to handle repeat&offset repeat&oszillate here, see UpdateAnimRangeSetup()
        switch (envl->pre) {
        case LWO::PrePostBehaviour_Linear:
            DoInterpolation2(cur, cur + 1, time, fill);
            return;

        case LWO::PrePostBehaviour_Reset:
            fill = 0.f;
            return;

        default: //case LWO::PrePostBehaviour_Constant:
            fill = (*cur).value;
            return;
        }
    }
    // check whether we're at the end of the animation track
    else if (cur == envl->keys.end() - 1 && time > envl->keys.rbegin()->time) {
        // ok ... this depends on post behaviour now
        switch (envl->post) {
        case LWO::PrePostBehaviour_Linear:
            DoInterpolation2(cur, cur - 1, time, fill);
            return;

        case LWO::PrePostBehaviour_Reset:
            fill = 0.f;
            return;

        default: //case LWO::PrePostBehaviour_Constant:
            fill = (*cur).value;
            return;
        }
    }

    // Otherwise do a simple interpolation
    DoInterpolation2(cur - 1, cur, time, fill);
}

// ------------------------------------------------------------------------------------------------
// Almost the same, except we won't handle pre/post conditions here
void AnimResolver::DoInterpolation2(std::vector<LWO::Key>::const_iterator beg,
        std::vector<LWO::Key>::const_iterator end, double time, float &fill) {
    switch ((*end).inter) {

    case LWO::IT_STEP:
        // no interpolation at all - take the value of the last key
        fill = (*beg).value;
        return;
    default:

        // silence compiler warning
        break;
    }
    // linear interpolation - default
    double duration = (*end).time - (*beg).time;
    if (duration > 0.0) {
        fill = (*beg).value + ((*end).value - (*beg).value) * (float)(((time - (*beg).time) / duration));
    } else {
        fill = (*beg).value;
    }
}

// ------------------------------------------------------------------------------------------------
// Subsample animation track by given key values
void AnimResolver::SubsampleAnimTrack(std::vector<aiVectorKey> & /*out*/,
        double /*time*/, double /*sample_delta*/) {
    //ai_assert(out.empty() && sample_delta);

    //const double time_start = out.back().mTime;
    //  for ()
}

// ------------------------------------------------------------------------------------------------
// Track interpolation
void AnimResolver::InterpolateTrack(std::vector<aiVectorKey> &out, aiVectorKey &fill, double time) {
    // subsample animation track?
    if (flags & AI_LWO_ANIM_FLAG_SAMPLE_ANIMS) {
        SubsampleAnimTrack(out, time, sample_delta);
    }

    fill.mTime = time;

    // get x
    if ((*cur_x).time == time) {
        fill.mValue.x = (*cur_x).value;

        if (cur_x != envl_x->keys.end() - 1) /* increment x */
            ++cur_x;
        else
            end_x = true;
    } else
        DoInterpolation(cur_x, envl_x, time, (float &)fill.mValue.x);

    // get y
    if ((*cur_y).time == time) {
        fill.mValue.y = (*cur_y).value;

        if (cur_y != envl_y->keys.end() - 1) /* increment y */
            ++cur_y;
        else
            end_y = true;
    } else
        DoInterpolation(cur_y, envl_y, time, (float &)fill.mValue.y);

    // get z
    if ((*cur_z).time == time) {
        fill.mValue.z = (*cur_z).value;

        if (cur_z != envl_z->keys.end() - 1) /* increment z */
            ++cur_z;
        else
            end_x = true;
    } else
        DoInterpolation(cur_z, envl_z, time, (float &)fill.mValue.z);
}

// ------------------------------------------------------------------------------------------------
// Build linearly subsampled keys from three single envelopes, one for each component (x,y,z)
void AnimResolver::GetKeys(std::vector<aiVectorKey> &out,
        LWO::Envelope *_envl_x,
        LWO::Envelope *_envl_y,
        LWO::Envelope *_envl_z,
        unsigned int _flags) {
    envl_x = _envl_x;
    envl_y = _envl_y;
    envl_z = _envl_z;
    flags = _flags;

    // generate default channels if none are given
    LWO::Envelope def_x, def_y, def_z;
    LWO::Key key_dummy;
    key_dummy.time = 0.f;
    if ((envl_x && envl_x->type == LWO::EnvelopeType_Scaling_X) ||
            (envl_y && envl_y->type == LWO::EnvelopeType_Scaling_Y) ||
            (envl_z && envl_z->type == LWO::EnvelopeType_Scaling_Z)) {
        key_dummy.value = 1.f;
    } else
        key_dummy.value = 0.f;

    if (!envl_x) {
        envl_x = &def_x;
        envl_x->keys.push_back(key_dummy);
    }
    if (!envl_y) {
        envl_y = &def_y;
        envl_y->keys.push_back(key_dummy);
    }
    if (!envl_z) {
        envl_z = &def_z;
        envl_z->keys.push_back(key_dummy);
    }

    // guess how many keys we'll get
    size_t reserve;
    double sr = 1.;
    if (flags & AI_LWO_ANIM_FLAG_SAMPLE_ANIMS) {
        if (!sample_rate)
            sr = 100.f;
        else
            sr = sample_rate;
        sample_delta = 1.f / sr;

        reserve = (size_t)(
                std::max(envl_x->keys.rbegin()->time,
                        std::max(envl_y->keys.rbegin()->time, envl_z->keys.rbegin()->time)) *
                sr);
    } else
        reserve = std::max(envl_x->keys.size(), std::max(envl_x->keys.size(), envl_z->keys.size()));
    out.reserve(reserve + (reserve >> 1));

    // Iterate through all three arrays at once - it's tricky, but
    // rather interesting to implement.
    cur_x = envl_x->keys.begin();
    cur_y = envl_y->keys.begin();
    cur_z = envl_z->keys.begin();

    end_x = end_y = end_z = false;
    while (true) {

        aiVectorKey fill;

        if ((*cur_x).time == (*cur_y).time && (*cur_x).time == (*cur_z).time) {

            // we have a keyframe for all of them defined .. this means
            // we don't need to interpolate here.
            fill.mTime = (*cur_x).time;

            fill.mValue.x = (*cur_x).value;
            fill.mValue.y = (*cur_y).value;
            fill.mValue.z = (*cur_z).value;

            // subsample animation track
            if (flags & AI_LWO_ANIM_FLAG_SAMPLE_ANIMS) {
                //SubsampleAnimTrack(out,cur_x, cur_y, cur_z, d, sample_delta);
            }
        }

        // Find key with lowest time value
        else if ((*cur_x).time <= (*cur_y).time && !end_x) {

            if ((*cur_z).time <= (*cur_x).time && !end_z) {
                InterpolateTrack(out, fill, (*cur_z).time);
            } else {
                InterpolateTrack(out, fill, (*cur_x).time);
            }
        } else if ((*cur_z).time <= (*cur_y).time && !end_y) {
            InterpolateTrack(out, fill, (*cur_y).time);
        } else if (!end_y) {
            // welcome on the server, y
            InterpolateTrack(out, fill, (*cur_y).time);
        } else {
            // we have reached the end of at least 2 channels,
            // only one is remaining. Extrapolate the 2.
            if (end_y) {
                InterpolateTrack(out, fill, (end_x ? (*cur_z) : (*cur_x)).time);
            } else if (end_x) {
                InterpolateTrack(out, fill, (end_z ? (*cur_y) : (*cur_z)).time);
            } else { // if (end_z)
                InterpolateTrack(out, fill, (end_y ? (*cur_x) : (*cur_y)).time);
            }
        }
        double lasttime = fill.mTime;
        out.push_back(fill);

        if (lasttime >= (*cur_x).time) {
            if (cur_x != envl_x->keys.end() - 1)
                ++cur_x;
            else
                end_x = true;
        }
        if (lasttime >= (*cur_y).time) {
            if (cur_y != envl_y->keys.end() - 1)
                ++cur_y;
            else
                end_y = true;
        }
        if (lasttime >= (*cur_z).time) {
            if (cur_z != envl_z->keys.end() - 1)
                ++cur_z;
            else
                end_z = true;
        }

        if (end_x && end_y && end_z) /* finished? */
            break;
    }

    if (flags & AI_LWO_ANIM_FLAG_START_AT_ZERO) {
        for (std::vector<aiVectorKey>::iterator it = out.begin(); it != out.end(); ++it)
            (*it).mTime -= first;
    }
}

// ------------------------------------------------------------------------------------------------
// Extract animation channel
void AnimResolver::ExtractAnimChannel(aiNodeAnim **out, unsigned int /*= 0*/) {
    *out = nullptr;

    //FIXME: crashes if more than one component is animated at different timings, to be resolved.

    // If we have no envelopes, return nullptr
    if (envelopes.empty()) {
        return;
    }

    // We won't spawn an animation channel if we don't have at least one envelope with more than one keyframe defined.
    const bool trans = ((trans_x && trans_x->keys.size() > 1) || (trans_y && trans_y->keys.size() > 1) || (trans_z && trans_z->keys.size() > 1));
    const bool rotat = ((rotat_x && rotat_x->keys.size() > 1) || (rotat_y && rotat_y->keys.size() > 1) || (rotat_z && rotat_z->keys.size() > 1));
    const bool scale = ((scale_x && scale_x->keys.size() > 1) || (scale_y && scale_y->keys.size() > 1) || (scale_z && scale_z->keys.size() > 1));
    if (!trans && !rotat && !scale)
        return;

    // Allocate the output animation
    aiNodeAnim *anim = *out = new aiNodeAnim();

    // Setup default animation setup if necessary
    if (need_to_setup) {
        UpdateAnimRangeSetup();
        need_to_setup = false;
    }

    // copy translation keys
    if (trans) {
        std::vector<aiVectorKey> keys;
        GetKeys(keys, trans_x, trans_y, trans_z, flags);

        anim->mPositionKeys = new aiVectorKey[anim->mNumPositionKeys = static_cast<unsigned int>(keys.size())];
        std::copy(keys.begin(), keys.end(), anim->mPositionKeys);
    }

    // copy rotation keys
    if (rotat) {
        std::vector<aiVectorKey> keys;
        GetKeys(keys, rotat_x, rotat_y, rotat_z, flags);

        anim->mRotationKeys = new aiQuatKey[anim->mNumRotationKeys = static_cast<unsigned int>(keys.size())];

        // convert heading, pitch, bank to quaternion
        // mValue.x=Heading=Rot(Y), mValue.y=Pitch=Rot(X), mValue.z=Bank=Rot(Z)
        // Lightwave's rotation order is ZXY
        aiVector3D X(1.0, 0.0, 0.0);
        aiVector3D Y(0.0, 1.0, 0.0);
        aiVector3D Z(0.0, 0.0, 1.0);
        for (unsigned int i = 0; i < anim->mNumRotationKeys; ++i) {
            aiQuatKey &qk = anim->mRotationKeys[i];
            qk.mTime = keys[i].mTime;
            qk.mValue = aiQuaternion(Y, keys[i].mValue.x) * aiQuaternion(X, keys[i].mValue.y) * aiQuaternion(Z, keys[i].mValue.z);
        }
    }

    // copy scaling keys
    if (scale) {
        std::vector<aiVectorKey> keys;
        GetKeys(keys, scale_x, scale_y, scale_z, flags);

        anim->mScalingKeys = new aiVectorKey[anim->mNumScalingKeys = static_cast<unsigned int>(keys.size())];
        std::copy(keys.begin(), keys.end(), anim->mScalingKeys);
    }
}

#endif // no lwo or no lws
