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

#include "AssimpPCH.h"
#if (!defined ASSIMP_BUILD_NO_LWO_IMPORTER) && (!defined ASSIMP_BUILD_NO_LWS_IMPORTER)

#include <functional>

// internal headers
#include "LWOFileData.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.)
{
	trans_x = trans_y = trans_z = NULL;
	rotat_x = rotat_y = rotat_z = NULL;
	scale_x = scale_y = scale_z = NULL;

	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;
		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 behaviours.
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;
		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 behaviour
		switch ((*it).pre) {
			case LWO::PrePostBehaviour_OffsetRepeat:
			case LWO::PrePostBehaviour_Repeat:
			case LWO::PrePostBehaviour_Oscillate:
				{
				const double start_time = delta - fmod(my_first-first,delta);
				std::vector<LWO::Key>::iterator n = std::find_if((*it).keys.begin(),(*it).keys.end(), 
					std::bind1st(std::greater<double>(),start_time)),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);

					if ((*it).pre == LWO::PrePostBehaviour_Oscillate && (reverse = !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 behaviour
		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
	fill = (*beg).value + ((*end).value - (*beg).value)*(float)(((time - (*beg).time) / ((*end).time - (*beg).time)));
}

// ------------------------------------------------------------------------------------------------
// 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.
	double lasttime = std::min(envl_x->keys[0].time,std::min(envl_y->keys[0].time,envl_z->keys[0].time));
	
	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 (1) {

		aiVectorKey fill;

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

			// we have a keyframe for all of them defined .. great,
			// we don't need to fucking 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);
			}
		}
		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 flags /*= 0*/)
{
	*out = NULL;


	//FIXME: crashes if more than one component is animated at different timings, to be resolved.
	
	// If we have no envelopes, return NULL
	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 = 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 = 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 = keys.size() ];
		std::copy(keys.begin(),keys.end(),anim->mScalingKeys);
	}
}


#endif // no lwo or no lws