assimp.assimp/code/RemoveRedundantMaterials.cpp

/*
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Open Asset Import Library (ASSIMP)
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*/
/** @file Implementation of the "RemoveRedundantMaterials" post processing step 
*/

// internal headers
#include "AssimpPCH.h"
#include "RemoveRedundantMaterials.h"

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
RemoveRedundantMatsProcess::RemoveRedundantMatsProcess()
{
	// nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
RemoveRedundantMatsProcess::~RemoveRedundantMatsProcess()
{
	// nothing to do here
}

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

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void RemoveRedundantMatsProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("RemoveRedundantMatsProcess begin");

	unsigned int iCnt = 0, unreferenced = 0;
	if (pScene->mNumMaterials)
	{
		// TODO: reimplement this algorithm to work in-place

		unsigned int* aiMappingTable = new unsigned int[pScene->mNumMaterials];
		unsigned int iNewNum = 0;

		std::vector<bool> abReferenced(pScene->mNumMaterials,false);
		for (unsigned int i = 0;i < pScene->mNumMeshes;++i)
			abReferenced[pScene->mMeshes[i]->mMaterialIndex] = true;

		// iterate through all materials and calculate a hash for them
		// store all hashes in a list and so a quick search whether
		// we do already have a specific hash. This allows us to
		// determine which materials are identical.
		uint32_t* aiHashes;
		aiHashes = new uint32_t[pScene->mNumMaterials];
		for (unsigned int i = 0; i < pScene->mNumMaterials;++i)
		{
			// if the material is not referenced ... remove it
			if (!abReferenced[i])
			{
				++unreferenced;
				continue;
			}

			uint32_t me = aiHashes[i] = ((MaterialHelper*)pScene->mMaterials[i])->ComputeHash();
			for (unsigned int a = 0; a < i;++a)
			{
				if (me == aiHashes[a])
				{				
					++iCnt;
					me = 0;
					aiMappingTable[i] = aiMappingTable[a];
					delete pScene->mMaterials[i];
					break;
				}
			}
			if (me)
			{
				aiMappingTable[i] = iNewNum++;
			}
		}
		if (iCnt)
		{
			// build an output material list
			aiMaterial** ppcMaterials = new aiMaterial*[iNewNum];
			::memset(ppcMaterials,0,sizeof(void*)*iNewNum); 
			for (unsigned int p = 0; p < pScene->mNumMaterials;++p)
			{
				// if the material is not referenced ... remove it
				if (!abReferenced[p])continue;

				// generate new names for all modified materials
				const unsigned int idx = aiMappingTable[p]; 
				if (ppcMaterials[idx]) 
				{
					aiString sz;
					sz.length = ::sprintf(sz.data,"aiMaterial #%i",p);
					((MaterialHelper*)ppcMaterials[idx])->AddProperty(&sz,AI_MATKEY_NAME);
				}
				else ppcMaterials[idx] = pScene->mMaterials[p];
			}
			// update all material indices
			for (unsigned int p = 0; p < pScene->mNumMeshes;++p)
			{
				aiMesh* mesh = pScene->mMeshes[p];
				mesh->mMaterialIndex = aiMappingTable[mesh->mMaterialIndex];
			}
			// delete the old material list
			delete[] pScene->mMaterials;
			pScene->mMaterials = ppcMaterials;
			pScene->mNumMaterials = iNewNum;
		}
		// delete temporary storage
		delete[] aiHashes;
		delete[] aiMappingTable;
	}
	if (!iCnt)DefaultLogger::get()->debug("RemoveRedundantMatsProcess finished ");
	else 
	{
		char szBuffer[128]; // should be sufficiently large
		::sprintf(szBuffer,"RemoveRedundantMatsProcess finished. %i redundant and %i unused materials",
			iCnt,unreferenced);
		DefaultLogger::get()->info(szBuffer);
	}
}