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Open Asset Import Library (assimp)
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/** @file  OptimizeGraph.cpp
 *  @brief Implementation of the aiProcess_OptimizGraph step
 */

#include "AssimpPCH.h"
#ifndef ASSIMP_BUILD_NO_OPTIMIZEGRAPH_PROCESS

using namespace Assimp;
#include "OptimizeGraph.h"
#include "ProcessHelper.h"
#include "SceneCombiner.h"

#define AI_RESERVED_NODE_NAME "$Reserved_And_Evil"

/* AI_OG_USE_HASHING enables the use of hashing to speed-up std::set lookups.
 * The unhashed variant should be faster, except for *very* large data sets
 */
#ifdef AI_OG_USE_HASHING
	// Use our standard hashing function to compute the hash 
#	define AI_OG_GETKEY(str) SuperFastHash(str.data,str.length)
#else
	// Otherwise hope that std::string will utilize a static buffer 
	// for shorter node names. This would avoid endless heap copying.
#	define AI_OG_GETKEY(str) std::string(str.data)
#endif

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
OptimizeGraphProcess::OptimizeGraphProcess()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
OptimizeGraphProcess::~OptimizeGraphProcess()
{}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool OptimizeGraphProcess::IsActive( unsigned int pFlags) const
{
	return (0 != (pFlags & aiProcess_OptimizeGraph));
}

// ------------------------------------------------------------------------------------------------
// Setup properties for the postprocessing step
void OptimizeGraphProcess::SetupProperties(const Importer* pImp)
{	
	// Get value of AI_CONFIG_PP_OG_EXCLUDE_LIST
	std::string tmp = pImp->GetPropertyString(AI_CONFIG_PP_OG_EXCLUDE_LIST,"");
	AddLockedNodeList(tmp);
}

// ------------------------------------------------------------------------------------------------
// Collect new children
void OptimizeGraphProcess::CollectNewChildren(aiNode* nd, std::list<aiNode*>& nodes)
{
	nodes_in += nd->mNumChildren;

	// Process children
	std::list<aiNode*> child_nodes;
	for (unsigned int i = 0; i < nd->mNumChildren; ++i) {

		CollectNewChildren(nd->mChildren[i],child_nodes);
		nd->mChildren[i] = NULL;
	}

	// Check whether we need this node; if not we can replace it by our own children (warn, danger of incest).
	if (locked.find(AI_OG_GETKEY(nd->mName)) == locked.end() ) {
		for (std::list<aiNode*>::iterator it = child_nodes.begin(); it != child_nodes.end();) {

			if (locked.find(AI_OG_GETKEY((*it)->mName)) == locked.end()) {
				(*it)->mTransformation = nd->mTransformation * (*it)->mTransformation;
				nodes.push_back(*it);

				it = child_nodes.erase(it);
				continue;
			}
			++it;
		}

		if (nd->mNumMeshes || child_nodes.size()) { 
			nodes.push_back(nd);
		}
		else {
			delete nd; /* bye, node */
			return;
		}
	}
	else {
		
		// Retain our current position in the hierarchy
		nodes.push_back(nd);

		// Now check for possible optimizations in our list of child nodes. join as many as possible
		aiNode* join_master = NULL;
		aiMatrix4x4 inv;

		const LockedSetType::const_iterator end = locked.end();

		std::list<aiNode*> join;
		for (std::list<aiNode*>::iterator it = child_nodes.begin(); it != child_nodes.end();)	{
			aiNode* child = *it;
			if (child->mNumChildren == 0 && locked.find(AI_OG_GETKEY(child->mName)) == end) {
			
				// There may be no instanced meshes
				unsigned int n = 0;
				for (; n < child->mNumMeshes;++n) {
					if (meshes[child->mMeshes[n]] > 1) {
						break;
					}
				}
				if (n == child->mNumMeshes) {

					if (!join_master) {
						join_master = child;
						inv = join_master->mTransformation;
						inv.Inverse();
					}
					else {

						child->mTransformation = inv * child->mTransformation ;

						join.push_back(child);	
						it = child_nodes.erase(it);
						continue;
					}
				}
			}
			++it;
		}
		if (join_master && join.size()) {
			join_master->mName.length = sprintf(join_master->mName.data,"$MergedNode_%i",count_merged++);

			unsigned int out_meshes = 0;
			for (std::list<aiNode*>::iterator it = join.begin(); it != join.end(); ++it) {
				out_meshes += (*it)->mNumMeshes;
			}
			
			// copy all mesh references in one array
			if (out_meshes) {
				unsigned int* meshes = new unsigned int[out_meshes+join_master->mNumMeshes], *tmp = meshes;
				for (unsigned int n = 0; n < join_master->mNumMeshes;++n) {
					*tmp++ = join_master->mMeshes[n];		
				}

				for (std::list<aiNode*>::iterator it = join.begin(); it != join.end(); ++it) {
					for (unsigned int n = 0; n < (*it)->mNumMeshes; ++n) {

						*tmp = (*it)->mMeshes[n];
						aiMesh* mesh = mScene->mMeshes[*tmp++];

						// manually move the mesh into the right coordinate system
						const aiMatrix3x3 IT = aiMatrix3x3( (*it)->mTransformation ).Inverse().Transpose(); 
						for (unsigned int a = 0; a < mesh->mNumVertices; ++a) {
						
							mesh->mVertices[a] *= (*it)->mTransformation;

							if (mesh->HasNormals())
								mesh->mNormals[a] *= IT;

							if (mesh->HasTangentsAndBitangents()) {
								mesh->mTangents[a] *= IT;
								mesh->mBitangents[a] *= IT;
							}
						}
					}
					delete *it; // bye, node
				}
				delete[] join_master->mMeshes;
				join_master->mMeshes = meshes;
				join_master->mNumMeshes += out_meshes;
			}
		}
	}
	// reassign children if something changed
	if (child_nodes.empty() || child_nodes.size() > nd->mNumChildren) {

		delete[] nd->mChildren;

		if (child_nodes.size())
			nd->mChildren = new aiNode*[child_nodes.size()];
		else nd->mChildren = NULL;
	}

	nd->mNumChildren = child_nodes.size();

	aiNode** tmp = nd->mChildren;
	for (std::list<aiNode*>::iterator it = child_nodes.begin(); it != child_nodes.end(); ++it) {
		aiNode* node = *tmp++ = *it;
		node->mParent = nd;
	}

	nodes_out += child_nodes.size();
}

// ------------------------------------------------------------------------------------------------
// Execute the postprocessing step on the given scene
void OptimizeGraphProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("OptimizeGraphProcess begin");
	nodes_in = nodes_out = count_merged = 0;
	mScene = pScene;

	meshes.resize(pScene->mNumMeshes,0);
	FindInstancedMeshes(pScene->mRootNode);

	// build a blacklist of identifiers. If the name of a node matches one of these, we won't touch it
	locked.clear();
	for (std::list<std::string>::const_iterator it = locked_nodes.begin(); it != locked_nodes.end(); ++it) {
#ifdef AI_OG_USE_HASHING
		locked.insert(SuperFastHash((*it).c_str()));
#else
		locked.insert(*it);
#endif
	}

	for (unsigned int i = 0; i < pScene->mNumAnimations; ++i) {
		for (unsigned int a = 0; a < pScene->mAnimations[i]->mNumChannels; ++a) {
		
			aiNodeAnim* anim = pScene->mAnimations[i]->mChannels[a];
			locked.insert(AI_OG_GETKEY(anim->mNodeName));
		}
	}

	for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
		for (unsigned int a = 0; a < pScene->mMeshes[i]->mNumBones; ++a) {
		
			aiBone* bone = pScene->mMeshes[i]->mBones[a];
			locked.insert(AI_OG_GETKEY(bone->mName));

			// HACK: Meshes referencing bones may not be transformed; we need to look them.
			// The easiest way to do this is to increase their reference counters ...
			meshes[i] += 2;
		}
	}

	for (unsigned int i = 0; i < pScene->mNumCameras; ++i) {
		aiCamera* cam = pScene->mCameras[i];
		locked.insert(AI_OG_GETKEY(cam->mName));
	}

	for (unsigned int i = 0; i < pScene->mNumLights; ++i) {
		aiLight* lgh = pScene->mLights[i];
		locked.insert(AI_OG_GETKEY(lgh->mName));
	}

	// Insert a dummy master node and make it read-only
	aiNode* dummy_root = new aiNode(AI_RESERVED_NODE_NAME);
	locked.insert(AI_OG_GETKEY(dummy_root->mName));

	const aiString prev = pScene->mRootNode->mName;
	pScene->mRootNode->mParent = dummy_root;

	dummy_root->mChildren = new aiNode*[dummy_root->mNumChildren = 1];
	dummy_root->mChildren[0] = pScene->mRootNode;

	// Do our recursive processing of scenegraph nodes. For each node collect
	// a fully new list of children and allow their children to place themselves
	// on the same hierarchy layer as their parents.
	std::list<aiNode*> nodes;
	CollectNewChildren (dummy_root,nodes);

	ai_assert(nodes.size() == 1);

	if (dummy_root->mNumChildren == 0) {
		pScene->mRootNode = NULL;
		throw DeadlyImportError("After optimizing the scene graph, no data remains");
	}

	if (dummy_root->mNumChildren > 1) {
		pScene->mRootNode = dummy_root;
	
		// Keep the dummy node but assign the name of the old root node to it
		pScene->mRootNode->mName = prev;
	}
	else {
		
		// Remove the dummy root node again.
		pScene->mRootNode = dummy_root->mChildren[0];

		dummy_root->mChildren[0] = NULL;
		delete dummy_root;
	}

	pScene->mRootNode->mParent = NULL;
	if (!DefaultLogger::isNullLogger()) {
		if ( nodes_in != nodes_out) {

			char buf[512];
			sprintf(buf,"OptimizeGraphProcess finished; Input nodes: %i, Output nodes: %i",nodes_in,nodes_out);
			DefaultLogger::get()->info(buf);
		}
		else DefaultLogger::get()->debug("OptimizeGraphProcess finished");
	}
	meshes.clear();
	locked.clear();
}

// ------------------------------------------------------------------------------------------------
// Buidl a LUT of all instanced meshes
void OptimizeGraphProcess::FindInstancedMeshes (aiNode* pNode)
{
	for (unsigned int i = 0; i < pNode->mNumMeshes;++i) {
		++meshes[pNode->mMeshes[i]]; 
	}

	for (unsigned int i = 0; i < pNode->mNumChildren; ++i)
		FindInstancedMeshes(pNode->mChildren[i]);
}

#endif // !! ASSIMP_BUILD_NO_OPTIMIZEGRAPH_PROCESS