assimp/code/SceneCombiner.cpp

/*
Open Asset Import Library (ASSIMP)
----------------------------------------------------------------------

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  following disclaimer.

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  written permission of the ASSIMP Development Team.

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----------------------------------------------------------------------
*/


// ----------------------------------------------------------------------------
/** @file Implements Assimp::SceneCombiner. This is a smart utility
 *    class that can be used to combine several scenes, meshes, ...
 *    in one. Currently these utilities are used by the IRR and LWS
 *    loaders and by the OptimizeGraph step.
 */
// ----------------------------------------------------------------------------
#include "AssimpPCH.h"
#include "SceneCombiner.h"
#include "fast_atof.h"
#include "Hash.h"
#include "time.h"

// ----------------------------------------------------------------------------
// We need boost::random here. The workaround uses rand() instead of a proper
// Mersenne twister, but I think it should still be 'random' enough for our
// purposes. 
// ----------------------------------------------------------------------------
#ifdef ASSIMP_BUILD_BOOST_WORKAROUND

#	include "../include/BoostWorkaround/boost/random/uniform_int.hpp"
#	include "../include/BoostWorkaround/boost/random/variate_generator.hpp"
#	include "../include/BoostWorkaround/boost/random/mersenne_twister.hpp"

#else

#	include <boost/random/uniform_int.hpp>
#	include <boost/random/variate_generator.hpp>
#	include <boost/random/mersenne_twister.hpp>

#endif


namespace Assimp	{

// ------------------------------------------------------------------------------------------------
// Add a prefix to a string
inline void PrefixString(aiString& string,const char* prefix, unsigned int len)
{
	// If the string is already prefixed, we won't prefix it a second time
	if (string.length >= 1 && string.data[0] == '$')
		return;

	// Add the prefix
	::memmove(string.data+len,string.data,string.length+1);
	::memcpy (string.data, prefix, len);

	// And update the string's length
	string.length += len;
}

// ------------------------------------------------------------------------------------------------
// Add node identifiers to a hashing set
void SceneCombiner::AddNodeHashes(aiNode* node, std::set<unsigned int>& hashes)
{
	// Add node name to hashing set if it is non-empty - empty nodes are allowed 
	// and they can't have any anims assigned so its absolutely safe to duplicate them.
	if (node->mName.length) {
		hashes.insert( SuperFastHash(node->mName.data,node->mName.length) );
	}

	// Process all children recursively
	for (unsigned int i = 0; i < node->mNumChildren;++i)
		AddNodeHashes(node->mChildren[i],hashes);
}

// ------------------------------------------------------------------------------------------------
// Add a name prefix to all nodes in a hierarchy
void SceneCombiner::AddNodePrefixes(aiNode* node, const char* prefix, unsigned int len)
{
	ai_assert(NULL != prefix);
	PrefixString(node->mName,prefix,len);

	// Process all children recursively
	for (unsigned int i = 0; i < node->mNumChildren;++i)
		AddNodePrefixes(node->mChildren[i],prefix,len);
}

// ------------------------------------------------------------------------------------------------
// Search for matching names
bool SceneCombiner::FindNameMatch(const aiString& name, std::vector<SceneHelper>& input, unsigned int cur)
{
	const unsigned int hash = SuperFastHash(name.data, name.length);

	// Check whether we find a positive match in one of the given sets
	for (unsigned int i = 0; i < input.size(); ++i) {

		if (cur != i && input[i].hashes.find(hash) != input[i].hashes.end()) {
			return true;
		}
	}
	return false;
}

// ------------------------------------------------------------------------------------------------
// Add a name prefix to all nodes in a hierarchy if a hash match is found
void SceneCombiner::AddNodePrefixesChecked(aiNode* node, const char* prefix, unsigned int len,
	std::vector<SceneHelper>& input, unsigned int cur)
{
	ai_assert(NULL != prefix);
	const unsigned int hash = SuperFastHash(node->mName.data,node->mName.length);

	// Check whether we find a positive match in one of the given sets
	for (unsigned int i = 0; i < input.size(); ++i) {

		if (cur != i && input[i].hashes.find(hash) != input[i].hashes.end()) {
			PrefixString(node->mName,prefix,len);
			break;
		}
	}

	// Process all children recursively
	for (unsigned int i = 0; i < node->mNumChildren;++i)
		AddNodePrefixesChecked(node->mChildren[i],prefix,len,input,cur);
}

// ------------------------------------------------------------------------------------------------
// Add an offset to all mesh indices in a node graph
void SceneCombiner::OffsetNodeMeshIndices (aiNode* node, unsigned int offset)
{
	for (unsigned int i = 0; i < node->mNumMeshes;++i)
		node->mMeshes[i] += offset;

	for (unsigned int i = 0; i < node->mNumChildren;++i)
		OffsetNodeMeshIndices(node->mChildren[i],offset);
}

// ------------------------------------------------------------------------------------------------
// Merges two scenes. Currently only used by the LWS loader.
void SceneCombiner::MergeScenes(aiScene** _dest,std::vector<aiScene*>& src,
	unsigned int flags)
{
	ai_assert(NULL != _dest);

	// if _dest points to NULL allocate a new scene. Otherwise clear the old and reuse it
	if (src.empty())
	{
		if (*_dest)
		{
			(*_dest)->~aiScene();
			SceneCombiner::CopySceneFlat(_dest,src[0]);
		}
		else *_dest = src[0];
		return;
	}
	if (*_dest)(*_dest)->~aiScene();
	else *_dest = new aiScene();

	// Create a dummy scene to serve as master for the others
	aiScene* master = new aiScene();
	master->mRootNode = new aiNode();
	master->mRootNode->mName.Set("<MergeRoot>");

	std::vector<AttachmentInfo> srcList (src.size());
	for (unsigned int i = 0; i < srcList.size();++i)	{
		srcList[i] = AttachmentInfo(src[i],master->mRootNode);
	}

	// 'master' will be deleted afterwards
	MergeScenes (_dest, master, srcList, flags);
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::AttachToGraph (aiNode* attach, std::vector<NodeAttachmentInfo>& srcList)
{
	unsigned int cnt;
	for (cnt = 0; cnt < attach->mNumChildren;++cnt)
		AttachToGraph(attach->mChildren[cnt],srcList);

	cnt = 0;
	for (std::vector<NodeAttachmentInfo>::iterator it = srcList.begin();
		 it != srcList.end(); ++it)
	{
		if ((*it).attachToNode == attach && !(*it).resolved)
			++cnt;
	}

	if (cnt)	{
		aiNode** n = new aiNode*[cnt+attach->mNumChildren];
		if (attach->mNumChildren)	{
			::memcpy(n,attach->mChildren,sizeof(void*)*attach->mNumChildren);
			delete[] attach->mChildren;
		}
		attach->mChildren = n;

		n += attach->mNumChildren;
		attach->mNumChildren += cnt;

		for (unsigned int i = 0; i < srcList.size();++i)	{
			NodeAttachmentInfo& att = srcList[i];
			if (att.attachToNode == attach && !att.resolved)	{
				*n = att.node;
				(**n).mParent = attach;
				++n;

				// mark this attachment as resolved
				att.resolved = true;
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::AttachToGraph ( aiScene* master, 
	std::vector<NodeAttachmentInfo>& src)
{
	ai_assert(NULL != master);
	AttachToGraph(master->mRootNode,src);
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::MergeScenes(aiScene** _dest, aiScene* master, 
	std::vector<AttachmentInfo>& srcList,
	unsigned int flags)
{
	ai_assert(NULL != _dest);

	// if _dest points to NULL allocate a new scene. Otherwise clear the old and reuse it
	if (srcList.empty())
	{
		if (*_dest)
		{
			(*_dest)->~aiScene();
			SceneCombiner::CopySceneFlat(_dest,master);
		}
		else *_dest = master;
		return;
	}
	if (*_dest)(*_dest)->~aiScene();
	else *_dest = new aiScene();

	aiScene* dest = *_dest;

	std::vector<SceneHelper> src (srcList.size()+1);
	src[0].scene = master;
	for (unsigned int i = 0; i < srcList.size();++i)	{
		src[i+1] = SceneHelper( srcList[i].scene );
	}

	// this helper array specifies which scenes are duplicates of others
	std::vector<unsigned int> duplicates(src.size(),0xffffffff);

	// this helper array is used as lookup table several times
	std::vector<unsigned int> offset(src.size());

	// Find duplicate scenes
	for (unsigned int i = 0; i < src.size();++i)
	{
		if (duplicates[i] != i && duplicates[i] != 0xffffffff)continue;
		duplicates[i] = i;
		for ( unsigned int a = i+1; a < src.size(); ++a)
		{
			if (src[i].scene == src[a].scene)
				duplicates[a] = i;
		}
	}

	// Generate unique names for all named stuff?
	if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES)
	{
		// Construct a proper random number generator
		boost::mt19937 rng( ::clock() );
		boost::uniform_int<> dist(1u,1 << 24u);
		boost::variate_generator<boost::mt19937&, boost::uniform_int<> > rndGen(rng, dist);   

		for (unsigned int i = 1; i < src.size();++i)
		{
			//if (i != duplicates[i]) 
			//{
			//	// duplicate scenes share the same UID
			//	::strcpy( src[i].id, src[duplicates[i]].id );
			//	src[i].idlen = src[duplicates[i]].idlen;

			//	continue;
			//}

			const unsigned int random = rndGen();
			src[i].idlen = ::sprintf(src[i].id,"$%.6X$_",random);

			if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
				
				// Compute hashes for all identifiers in this scene and store them
				// in a sorted table (for convenience I'm using std::set). We hash
				// just the node and animation channel names, all identifiers except
				// the material names should be caught by doing this.
				AddNodeHashes(src[i]->mRootNode,src[i].hashes);

				for (unsigned int a = 0; a < src[i]->mNumAnimations;++a) {
					aiAnimation* anim = src[i]->mAnimations[a];
					src[i].hashes.insert(SuperFastHash(anim->mName.data,anim->mName.length));
				}
			}
		}
	}
	
	unsigned int cnt;

	// First find out how large the respective output arrays must be
	for ( unsigned int n = 0; n < src.size();++n )
	{
		SceneHelper* cur = &src[n];

		if (n == duplicates[n] || flags & AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY)	{
			dest->mNumTextures   += (*cur)->mNumTextures;
			dest->mNumMaterials  += (*cur)->mNumMaterials;
			dest->mNumMeshes     += (*cur)->mNumMeshes;
		}

		dest->mNumLights     += (*cur)->mNumLights;
		dest->mNumCameras    += (*cur)->mNumCameras;
		dest->mNumAnimations += (*cur)->mNumAnimations;

		// Combine the flags of all scenes
		// We need to process them flag-by-flag here to get correct results
		// dest->mFlags ; //|= (*cur)->mFlags;
		if ((*cur)->mFlags & AI_SCENE_FLAGS_NON_VERBOSE_FORMAT) {
			dest->mFlags |= AI_SCENE_FLAGS_NON_VERBOSE_FORMAT;
		}
	}

	// generate the output texture list + an offset table for all texture indices
	if (dest->mNumTextures)
	{
		aiTexture** pip = dest->mTextures = new aiTexture*[dest->mNumMaterials];
		cnt = 0;
		for ( unsigned int n = 0; n < src.size();++n )
		{
			SceneHelper* cur = &src[n];
			for (unsigned int i = 0; i < (*cur)->mNumTextures;++i)
			{
				if (n != duplicates[n])
				{
					if ( flags & AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY)
						Copy(pip,(*cur)->mTextures[i]);

					else continue;
				}
				else *pip = (*cur)->mTextures[i];
				++pip;
			}

			offset[n] = cnt;
			cnt = (unsigned int)(pip - dest->mTextures);
		}
	}

	// generate the output material list + an offset table for all material indices
	if (dest->mNumMaterials)
	{ 
		aiMaterial** pip = dest->mMaterials = new aiMaterial*[dest->mNumMaterials];
		cnt = 0;
		for ( unsigned int n = 0; n < src.size();++n )	{
			SceneHelper* cur = &src[n];
			for (unsigned int i = 0; i < (*cur)->mNumMaterials;++i)
			{
				if (n != duplicates[n])
				{
					if ( flags & AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY)
						Copy(pip,(*cur)->mMaterials[i]);

					else continue;
				}
				else *pip = (*cur)->mMaterials[i];

				if ((*cur)->mNumTextures != dest->mNumTextures)		{
					// We need to update all texture indices of the mesh. So we need to search for
					// a material property called '$tex.file'

					for (unsigned int a = 0; a < (*pip)->mNumProperties;++a)
					{
						aiMaterialProperty* prop = (*pip)->mProperties[a];
						if (!strncmp(prop->mKey.data,"$tex.file",9))
						{
							// Check whether this texture is an embedded texture.
							// In this case the property looks like this: *<n>,
							// where n is the index of the texture.
							aiString& s = *((aiString*)prop->mData);
							if ('*' == s.data[0])	{
								// Offset the index and write it back ..
								const unsigned int idx = strtol10(&s.data[1]) + offset[n];
								ASSIMP_itoa10(&s.data[1],sizeof(s.data)-1,idx);
							}
						}

						// Need to generate new, unique material names?
						else if (!::strcmp( prop->mKey.data,"$mat.name" ) && flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_MATNAMES)
						{
							aiString* pcSrc = (aiString*) prop->mData; 
							PrefixString(*pcSrc, (*cur).id, (*cur).idlen);
						}
					}
				}
				++pip;
			}

			offset[n] = cnt;
			cnt = (unsigned int)(pip - dest->mMaterials);
		}
	}

	// generate the output mesh list + again an offset table for all mesh indices
	if (dest->mNumMeshes)
	{
		aiMesh** pip = dest->mMeshes = new aiMesh*[dest->mNumMeshes];
		cnt = 0;
		for ( unsigned int n = 0; n < src.size();++n )
		{
			SceneHelper* cur = &src[n];
			for (unsigned int i = 0; i < (*cur)->mNumMeshes;++i)
			{
				if (n != duplicates[n])	{
					if ( flags & AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY)
						Copy(pip, (*cur)->mMeshes[i]);

					else continue;
				}
				else *pip = (*cur)->mMeshes[i];

				// update the material index of the mesh
				(*pip)->mMaterialIndex +=  offset[n];
				++pip;
			}

			// reuse the offset array - store now the mesh offset in it
			offset[n] = cnt;
			cnt = (unsigned int)(pip - dest->mMeshes);
		}
	}

	std::vector <NodeAttachmentInfo> nodes;
	nodes.reserve(srcList.size());

	// ----------------------------------------------------------------------------
	// Now generate the output node graph. We need to make those
	// names in the graph that are referenced by anims or lights
	// or cameras unique. So we add a prefix to them ... $<rand>_
	// We could also use a counter, but using a random value allows us to
	// use just one prefix if we are joining multiple scene hierarchies recursively.
	// Chances are quite good we don't collide, so we try that ...
	// ----------------------------------------------------------------------------

	// Allocate space for light sources, cameras and animations
	aiLight** ppLights = dest->mLights = (dest->mNumLights 
		? new aiLight*[dest->mNumLights] : NULL);

	aiCamera** ppCameras = dest->mCameras = (dest->mNumCameras 
		? new aiCamera*[dest->mNumCameras] : NULL);

	aiAnimation** ppAnims = dest->mAnimations = (dest->mNumAnimations 
		? new aiAnimation*[dest->mNumAnimations] : NULL);

	for ( int n = src.size()-1; n >= 0 ;--n ) /* !!! important !!! */
	{
		SceneHelper* cur = &src[n];
		aiNode* node;

		// To offset or not to offset, this is the question
		if (n != duplicates[n])
		{
			// Get full scenegraph copy
			Copy( &node, (*cur)->mRootNode );
			OffsetNodeMeshIndices(node,offset[duplicates[n]]);

			if (flags & AI_INT_MERGE_SCENE_DUPLICATES_DEEP_CPY)	{
				// (note:) they are already 'offseted' by offset[duplicates[n]] 
				OffsetNodeMeshIndices(node,offset[n] - offset[duplicates[n]]);
			}
		}
		else // if (n == duplicates[n])
		{
			node = (*cur)->mRootNode;
			OffsetNodeMeshIndices(node,offset[n]);
		}
		if (n) // src[0] is the master node
			nodes.push_back(NodeAttachmentInfo( node,srcList[n-1].attachToNode,n ));

		// add name prefixes?
		if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES) {

			// or the whole scenegraph
			if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
				AddNodePrefixesChecked(node,(*cur).id,(*cur).idlen,src,n);
			}
			else AddNodePrefixes(node,(*cur).id,(*cur).idlen);

			// meshes
			for (unsigned int i = 0; i < (*cur)->mNumMeshes;++i)	{
				aiMesh* mesh = (*cur)->mMeshes[i]; 

				// rename all bones
				for (unsigned int a = 0; a < mesh->mNumBones;++a)	{
					if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
						if (!FindNameMatch(mesh->mBones[a]->mName,src,n))
							continue;
					}
					PrefixString(mesh->mBones[a]->mName,(*cur).id,(*cur).idlen);
				}
			}
		}

		// --------------------------------------------------------------------
		// Copy light sources
		for (unsigned int i = 0; i < (*cur)->mNumLights;++i,++ppLights)
		{
			if (n != duplicates[n]) // duplicate scene? 
			{
				Copy(ppLights, (*cur)->mLights[i]);
			}
			else *ppLights = (*cur)->mLights[i];


			// Add name prefixes?
			if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES) {
				if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
					if (!FindNameMatch((*ppLights)->mName,src,n))
						continue;
				}

				PrefixString((*ppLights)->mName,(*cur).id,(*cur).idlen);
			}
		}

		// --------------------------------------------------------------------
		// Copy cameras
		for (unsigned int i = 0; i < (*cur)->mNumCameras;++i,++ppCameras)	{
			if (n != duplicates[n]) // duplicate scene? 
			{
				Copy(ppCameras, (*cur)->mCameras[i]);
			}
			else *ppCameras = (*cur)->mCameras[i];

			// Add name prefixes?
			if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES) {
				if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
					if (!FindNameMatch((*ppCameras)->mName,src,n))
						continue;
				}

				PrefixString((*ppCameras)->mName,(*cur).id,(*cur).idlen);
			}
		}

		// --------------------------------------------------------------------
		// Copy animations
		for (unsigned int i = 0; i < (*cur)->mNumAnimations;++i,++ppAnims)	{
			if (n != duplicates[n]) // duplicate scene? 
			{
				Copy(ppAnims, (*cur)->mAnimations[i]);
			}
			else *ppAnims = (*cur)->mAnimations[i];

			// Add name prefixes?
			if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES) {
				if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
					if (!FindNameMatch((*ppAnims)->mName,src,n))
						continue;
				}

				PrefixString((*ppAnims)->mName,(*cur).id,(*cur).idlen);

				// don't forget to update all node animation channels
				for (unsigned int a = 0; a < (*ppAnims)->mNumChannels;++a) {
					if (flags & AI_INT_MERGE_SCENE_GEN_UNIQUE_NAMES_IF_NECESSARY) {
						if (!FindNameMatch((*ppAnims)->mChannels[a]->mNodeName,src,n))
							continue;
					}

					PrefixString((*ppAnims)->mChannels[a]->mNodeName,(*cur).id,(*cur).idlen);
				}
			}
		}
	}

	// Now build the output graph
	AttachToGraph ( master, nodes);
	dest->mRootNode = master->mRootNode;

	// Check whether we succeeded at building the output graph
	for (std::vector <NodeAttachmentInfo> ::iterator it = nodes.begin(); 
		it != nodes.end(); ++it)
	{
		if (!(*it).resolved) {
			if (flags & AI_INT_MERGE_SCENE_RESOLVE_CROSS_ATTACHMENTS) {
				// search for this attachment point in all other imported scenes, too.
				for ( unsigned int n = 0; n < src.size();++n ) {
					if (n != (*it).src_idx) {
						AttachToGraph(src[n].scene,nodes);
						if ((*it).resolved)
							break;
					}
				}
			}
			if (!(*it).resolved) {
				DefaultLogger::get()->error(std::string("SceneCombiner: Failed to resolve attachment ") 
					+ (*it).node->mName.data + " " + (*it).attachToNode->mName.data);
			}
		}
	}

	// now delete all input scenes. Make sure duplicate scenes aren't
	// deleted more than one time
	for ( unsigned int n = 0; n < src.size();++n )	{
		if (n != duplicates[n]) // duplicate scene?
			continue;

		aiScene* deleteMe = src[n].scene;

		// We need to delete the arrays before the destructor is called -
		// we are reusing the array members
		delete[] deleteMe->mMeshes;     deleteMe->mMeshes     = NULL;
		delete[] deleteMe->mCameras;    deleteMe->mCameras    = NULL;
		delete[] deleteMe->mLights;     deleteMe->mLights     = NULL;
		delete[] deleteMe->mMaterials;  deleteMe->mMaterials  = NULL;
		delete[] deleteMe->mAnimations; deleteMe->mAnimations = NULL;

		deleteMe->mRootNode = NULL;

		// Now we can safely delete the scene
		delete deleteMe;
	}

	// Check flags
	if (!dest->mNumMeshes || !dest->mNumMaterials) {
		dest->mFlags |= AI_SCENE_FLAGS_INCOMPLETE;
	}

	// We're finished
}

// ------------------------------------------------------------------------------------------------
// Build a list of unique bones
void SceneCombiner::BuildUniqueBoneList(std::list<BoneWithHash>& asBones,
	std::vector<aiMesh*>::const_iterator it,
	std::vector<aiMesh*>::const_iterator end)
{
	unsigned int iOffset = 0;
	for (; it != end;++it)
	{
		for (unsigned int l = 0; l < (*it)->mNumBones;++l)
		{
			aiBone* p = (*it)->mBones[l];
			uint32_t itml = SuperFastHash(p->mName.data,(unsigned int)p->mName.length);

			std::list<BoneWithHash>::iterator it2  = asBones.begin();
			std::list<BoneWithHash>::iterator end2 = asBones.end();

			for (;it2 != end2;++it2)	{
				if ((*it2).first == itml)	{
					(*it2).pSrcBones.push_back(BoneSrcIndex(p,iOffset));
					break;
				}
			}
			if (end2 == it2)
			{
				// need to begin a new bone entry
				asBones.push_back(BoneWithHash());
				BoneWithHash& btz = asBones.back();

				// setup members
				btz.first = itml;
				btz.second = &p->mName;
				btz.pSrcBones.push_back(BoneSrcIndex(p,iOffset));
			}
		}
		iOffset += (*it)->mNumVertices;
	}
}

// ------------------------------------------------------------------------------------------------
// Merge a list of bones
void SceneCombiner::MergeBones(aiMesh* out,std::vector<aiMesh*>::const_iterator it,
	std::vector<aiMesh*>::const_iterator end)
{
	ai_assert(NULL != out && !out->mNumBones);

	// find we need to build an unique list of all bones.
	// we work with hashes to make the comparisons MUCH faster,
	// at least if we have many bones.
	std::list<BoneWithHash> asBones;
	BuildUniqueBoneList(asBones, it,end);
	
	// now create the output bones
	out->mBones = new aiBone*[asBones.size()];

	for (std::list<BoneWithHash>::const_iterator it = asBones.begin(),end = asBones.end(); 
		 it != end;++it)
	{
		// Allocate a bone and setup it's name
		aiBone* pc = out->mBones[out->mNumBones++] = new aiBone();
		pc->mName = aiString( *((*it).second ));

		// Get an itrator to the end of the list
		std::vector< BoneSrcIndex >::const_iterator wend = (*it).pSrcBones.end();

		// Loop through all bones to be joined for this bone
		for (std::vector< BoneSrcIndex >::const_iterator 
			wmit = (*it).pSrcBones.begin(); wmit != wend; ++wmit)
		{
			pc->mNumWeights += (*wmit).first->mNumWeights;

			// NOTE: different offset matrices for bones with equal names
			// are - at the moment - not handled correctly. 
			if (wmit != (*it).pSrcBones.begin() &&
				pc->mOffsetMatrix != (*wmit).first->mOffsetMatrix)
			{
				DefaultLogger::get()->warn("Bones with equal names but different offset matrices can't be joined at the moment");
				continue;
			}
			pc->mOffsetMatrix = (*wmit).first->mOffsetMatrix;
		}

		// Allocate the vertex weight array
		aiVertexWeight* avw = pc->mWeights = new aiVertexWeight[pc->mNumWeights];

		// And copy the final weights - adjust the vertex IDs by the 
		// face index offset of the coresponding mesh.
		for (std::vector< BoneSrcIndex >::const_iterator 
			wmit = (*it).pSrcBones.begin(); wmit != wend; ++wmit)
		{
			aiBone* pip = (*wmit).first;
			for (unsigned int mp = 0; mp < pip->mNumWeights;++mp,++avw)
			{
				const aiVertexWeight& vfi = pip->mWeights[mp];
				avw->mWeight = vfi.mWeight;
				avw->mVertexId = vfi.mVertexId + (*wmit).second;
			}
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Merge a list of meshes
void SceneCombiner::MergeMeshes(aiMesh** _out,unsigned int flags,
	std::vector<aiMesh*>::const_iterator begin,
	std::vector<aiMesh*>::const_iterator end)
{
	ai_assert(NULL != _out);

	if (begin == end)
	{
		*_out = NULL; // no meshes ...
		return;
	}

	// Allocate the output mesh
	aiMesh* out = *_out = new aiMesh();
	out->mMaterialIndex = (*begin)->mMaterialIndex;

	// Find out how much output storage we'll need
	for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
	{
		out->mNumVertices	+= (*it)->mNumVertices;
		out->mNumFaces		+= (*it)->mNumFaces;
		out->mNumBones		+= (*it)->mNumBones;

		// combine primitive type flags
		out->mPrimitiveTypes |= (*it)->mPrimitiveTypes;
	}

	if (out->mNumVertices) // just for safety
	{
		aiVector3D* pv2;

		// copy vertex positions
		if ((**begin).HasPositions())
		{
			pv2 = out->mVertices = new aiVector3D[out->mNumVertices];
			for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
			{
				if ((*it)->mNormals)
				{
					::memcpy(pv2,(*it)->mVertices,(*it)->mNumVertices*sizeof(aiVector3D));
				}
				else DefaultLogger::get()->warn("JoinMeshes: Positions expected, but mesh contains no positions");
				pv2 += (*it)->mNumVertices;
			}
		}
		// copy normals
		if ((**begin).HasNormals())
		{
			pv2 = out->mNormals = new aiVector3D[out->mNumVertices];
			for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
			{
				if ((*it)->mNormals)
				{
					::memcpy(pv2,(*it)->mNormals,(*it)->mNumVertices*sizeof(aiVector3D));
				}
				else DefaultLogger::get()->warn("JoinMeshes: Normals expected, but mesh contains no normals");
				pv2 += (*it)->mNumVertices;
			}
		}
		// copy tangents and bitangents
		if ((**begin).HasTangentsAndBitangents())
		{
			pv2 = out->mTangents = new aiVector3D[out->mNumVertices];
			aiVector3D* pv2b = out->mBitangents = new aiVector3D[out->mNumVertices];

			for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
			{
				if ((*it)->mTangents)
				{
					::memcpy(pv2, (*it)->mTangents,	 (*it)->mNumVertices*sizeof(aiVector3D));
					::memcpy(pv2b,(*it)->mBitangents,(*it)->mNumVertices*sizeof(aiVector3D));
				}
				else DefaultLogger::get()->warn("JoinMeshes: Tangents expected, but mesh contains no tangents");
				pv2  += (*it)->mNumVertices;
				pv2b += (*it)->mNumVertices;
			}
		}
		// copy texture coordinates
		unsigned int n = 0;
		while ((**begin).HasTextureCoords(n))
		{
			out->mNumUVComponents[n] = (*begin)->mNumUVComponents[n];

			pv2 = out->mTextureCoords[n] = new aiVector3D[out->mNumVertices];
			for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
			{
				if ((*it)->mTextureCoords[n])
				{
					::memcpy(pv2,(*it)->mTextureCoords[n],(*it)->mNumVertices*sizeof(aiVector3D));
				}
				else DefaultLogger::get()->warn("JoinMeshes: UVs expected, but mesh contains no UVs");
				pv2 += (*it)->mNumVertices;
			}
			++n;
		}
		// copy vertex colors
		n = 0;
		while ((**begin).HasVertexColors(n))
		{
			aiColor4D* pv2 = out->mColors[n] = new aiColor4D[out->mNumVertices];
			for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
			{
				if ((*it)->mColors[n])
				{
					::memcpy(pv2,(*it)->mColors[n],(*it)->mNumVertices*sizeof(aiColor4D));
				}
				else DefaultLogger::get()->warn("JoinMeshes: VCs expected, but mesh contains no VCs");
				pv2 += (*it)->mNumVertices;
			}
			++n;
		}
	}

	if (out->mNumFaces) // just for safety
	{
		// copy faces
		out->mFaces = new aiFace[out->mNumFaces];
		aiFace* pf2 = out->mFaces;

		unsigned int ofs = 0;
		for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
		{
			for (unsigned int m = 0; m < (*it)->mNumFaces;++m,++pf2)
			{
				aiFace& face = (*it)->mFaces[m];
				pf2->mNumIndices = face.mNumIndices;
				pf2->mIndices = face.mIndices;

				if (ofs)
				{
					// add the offset to the vertex
					for (unsigned int q = 0; q < face.mNumIndices; ++q)
						face.mIndices[q] += ofs;	
				}
				ofs += (*it)->mNumVertices;
				face.mIndices = NULL;
			}
		}
	}

	// bones - as this is quite lengthy, I moved the code to a separate function
	if (out->mNumBones)
		MergeBones(out,begin,end);

	// delete all source meshes
	for (std::vector<aiMesh*>::const_iterator it = begin; it != end;++it)
		delete *it;
}

// ------------------------------------------------------------------------------------------------
template <typename Type>
inline void CopyPtrArray (Type**& dest, Type** src, unsigned int num)
{
	if (!num)
	{
		dest = NULL;
		return;
	}
	dest = new Type*[num];
	for (unsigned int i = 0; i < num;++i)
		SceneCombiner::Copy(&dest[i],src[i]);
}

// ------------------------------------------------------------------------------------------------
template <typename Type>
inline void GetArrayCopy (Type*& dest, unsigned int num )
{
	if (!dest)return;
	Type* old = dest;

	dest = new Type[num];
	::memcpy(dest, old, sizeof(Type) * num);
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::CopySceneFlat(aiScene** _dest,aiScene* src)
{
	// reuse the old scene or allocate a new?
	if (*_dest)(*_dest)->~aiScene();
	else *_dest = new aiScene();

	::memcpy(*_dest,src,sizeof(aiScene));
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::CopyScene(aiScene** _dest,aiScene* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiScene* dest = *_dest = new aiScene();

	// copy animations
	dest->mNumAnimations = src->mNumAnimations;
	CopyPtrArray(dest->mAnimations,src->mAnimations,
		dest->mNumAnimations);

	// copy textures
	dest->mNumTextures = src->mNumTextures;
	CopyPtrArray(dest->mTextures,src->mTextures,
		dest->mNumTextures);

	// copy materials
	dest->mNumMaterials = src->mNumMaterials;
	CopyPtrArray(dest->mMaterials,src->mMaterials,
		dest->mNumMaterials);

	// copy lights
	dest->mNumLights = src->mNumLights;
	CopyPtrArray(dest->mLights,src->mLights,
		dest->mNumLights);

	// copy cameras
	dest->mNumCameras = src->mNumCameras;
	CopyPtrArray(dest->mCameras,src->mCameras,
		dest->mNumCameras);

	// copy meshes
	dest->mNumMeshes = src->mNumMeshes;
	CopyPtrArray(dest->mMeshes,src->mMeshes,
		dest->mNumMeshes);

	// now - copy the root node of the scene (deep copy, too)
	Copy( &dest->mRootNode, src->mRootNode);

	// and keep the flags ...
	dest->mFlags = src->mFlags;
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy     (aiMesh** _dest, const aiMesh* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiMesh* dest = *_dest = new aiMesh();

	// get a flat copy
	::memcpy(dest,src,sizeof(aiMesh));

	// and reallocate all arrays
	GetArrayCopy( dest->mVertices,   dest->mNumVertices );
	GetArrayCopy( dest->mNormals ,   dest->mNumVertices );
	GetArrayCopy( dest->mTangents,   dest->mNumVertices );
	GetArrayCopy( dest->mBitangents, dest->mNumVertices );

	unsigned int n = 0;
	while (dest->HasTextureCoords(n))
		GetArrayCopy( dest->mTextureCoords[n++],   dest->mNumVertices );

	n = 0;
	while (dest->HasVertexColors(n))
		GetArrayCopy( dest->mColors[n++],   dest->mNumVertices );

	// make a deep copy of all bones
	CopyPtrArray(dest->mBones,dest->mBones,dest->mNumBones);

	// make a deep copy of all faces
	GetArrayCopy(dest->mFaces,dest->mNumFaces);
	for (unsigned int i = 0; i < dest->mNumFaces;++i)
	{
		aiFace& f = dest->mFaces[i];
		GetArrayCopy(f.mIndices,f.mNumIndices);
	}
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy (aiMaterial** _dest, const aiMaterial* src)
{
	ai_assert(NULL != _dest && NULL != src);

	MaterialHelper* dest = (MaterialHelper*) ( *_dest = new MaterialHelper() );
	dest->mNumAllocated  =  src->mNumAllocated;
	dest->mNumProperties =  src->mNumProperties;
	dest->mProperties    =  new aiMaterialProperty* [dest->mNumAllocated];

	for (unsigned int i = 0; i < dest->mNumProperties;++i)
	{
		aiMaterialProperty* prop  = dest->mProperties[i] = new aiMaterialProperty();
		aiMaterialProperty* sprop = src->mProperties[i];

		prop->mDataLength = sprop->mDataLength;
		prop->mData = new char[prop->mDataLength];
		::memcpy(prop->mData,sprop->mData,prop->mDataLength);

		prop->mIndex    = sprop->mIndex;
		prop->mSemantic = sprop->mSemantic;
		prop->mKey      = sprop->mKey;
		prop->mType		= sprop->mType;
	}
}
	
// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy  (aiTexture** _dest, const aiTexture* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiTexture* dest = *_dest = new aiTexture();

	// get a flat copy
	::memcpy(dest,src,sizeof(aiTexture));

	// and reallocate all arrays. We must do it manually here
	const char* old = (const char*)dest->pcData;
	if (old)
	{
		unsigned int cpy;
		if (!dest->mHeight)cpy = dest->mWidth;
		else cpy = dest->mHeight * dest->mWidth * sizeof(aiTexel);

		if (!cpy)
		{
			dest->pcData = NULL;
			return;
		}
		// the cast is legal, the aiTexel c'tor does nothing important
		dest->pcData = (aiTexel*) new char[cpy];
		::memcpy(dest->pcData, old, cpy);
	}
}
	
// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy     (aiAnimation** _dest, const aiAnimation* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiAnimation* dest = *_dest = new aiAnimation();

	// get a flat copy
	::memcpy(dest,src,sizeof(aiAnimation));

	// and reallocate all arrays
	CopyPtrArray( dest->mChannels, src->mChannels, dest->mNumChannels );
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy     (aiNodeAnim** _dest, const aiNodeAnim* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiNodeAnim* dest = *_dest = new aiNodeAnim();

	// get a flat copy
	::memcpy(dest,src,sizeof(aiNodeAnim));

	// and reallocate all arrays
	GetArrayCopy( dest->mPositionKeys, dest->mNumPositionKeys );
	GetArrayCopy( dest->mScalingKeys,  dest->mNumScalingKeys );
	GetArrayCopy( dest->mRotationKeys, dest->mNumRotationKeys );
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy   (aiCamera** _dest,const  aiCamera* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiCamera* dest = *_dest = new aiCamera();

	// get a flat copy, that's already OK
	::memcpy(dest,src,sizeof(aiCamera));
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy   (aiLight** _dest, const aiLight* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiLight* dest = *_dest = new aiLight();

	// get a flat copy, that's already OK
	::memcpy(dest,src,sizeof(aiLight));
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy     (aiBone** _dest, const aiBone* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiBone* dest = *_dest = new aiBone();

	// get a flat copy
	::memcpy(dest,src,sizeof(aiBone));

	// and reallocate all arrays
	GetArrayCopy( dest->mWeights, dest->mNumWeights );
}

// ------------------------------------------------------------------------------------------------
void SceneCombiner::Copy     (aiNode** _dest, const aiNode* src)
{
	ai_assert(NULL != _dest && NULL != src);

	aiNode* dest = *_dest = new aiNode();

	// get a flat copy
	::memcpy(dest,src,sizeof(aiNode));

	// and reallocate all arrays
	GetArrayCopy( dest->mMeshes, dest->mNumMeshes );
	CopyPtrArray( dest->mChildren, src->mChildren,dest->mNumChildren);
}


}