assimp/code/OptimizeMeshes.cpp

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

Copyright (c) 2006-2012, assimp team

All rights reserved.

Redistribution and use of this software in source and binary forms, 
with or without modification, are permitted provided that the following 
conditions are met:

* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
  materials provided with the distribution.

* Neither the name of the assimp team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the assimp team.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
---------------------------------------------------------------------------
*/

/** @file  OptimizeMeshes.cpp
 *  @brief Implementation of the aiProcess_OptimizeMeshes step
 */

#include "AssimpPCH.h"
#ifndef ASSIMP_BUILD_NO_OPTIMIZEMESHES_PROCESS

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

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
OptimizeMeshesProcess::OptimizeMeshesProcess()
: pts (false)
, max_verts (0xffffffff)
, max_faces (0xffffffff)
{}

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

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool OptimizeMeshesProcess::IsActive( unsigned int pFlags) const
{
	// Our behaviour needs to be different if the SortByPType or SplitLargeMeshes
	// steps are active. Thus we need to query their flags here and store the
	// information, although we're breaking const-correctness. 
	// That's a serious design flaw, consider redesign.
	if( 0 != (pFlags & aiProcess_OptimizeMeshes) ) {
		pts = (0 != (pFlags & aiProcess_SortByPType));
		max_verts = (0 != (pFlags & aiProcess_SplitLargeMeshes)) ? 0xdeadbeef : max_verts;
		return true;
	}
	return false;
}

// ------------------------------------------------------------------------------------------------
// Setup properties for the postprocessing step
void OptimizeMeshesProcess::SetupProperties(const Importer* pImp)
{
	if (max_verts == 0xdeadbeef /* magic hack */) {
		max_faces = pImp->GetPropertyInteger(AI_CONFIG_PP_SLM_TRIANGLE_LIMIT,AI_SLM_DEFAULT_MAX_TRIANGLES);
		max_verts = pImp->GetPropertyInteger(AI_CONFIG_PP_SLM_VERTEX_LIMIT,AI_SLM_DEFAULT_MAX_VERTICES);
	}
}

// ------------------------------------------------------------------------------------------------
// Execute step
void OptimizeMeshesProcess::Execute( aiScene* pScene)
{
	const unsigned int num_old = pScene->mNumMeshes;
	if (num_old <= 1) {
		DefaultLogger::get()->debug("Skipping OptimizeMeshesProcess");
		return;
	}

	DefaultLogger::get()->debug("OptimizeMeshesProcess begin");
	mScene = pScene;

	// need to clear persistent members from previous runs
	merge_list.clear();
	output.clear();

	merge_list.reserve(pScene->mNumMeshes);
	output.reserve(pScene->mNumMeshes);

	// Prepare lookup tables
	meshes.resize(pScene->mNumMeshes);
	FindInstancedMeshes(pScene->mRootNode);
	if (max_verts == 0xdeadbeef) /* undo the magic hack */
		max_verts = 0xffffffff;

	// ... instanced meshes are immediately processed and added to the output list
	for (unsigned int i = 0, n = 0; i < pScene->mNumMeshes;++i) {
		meshes[i].vertex_format = GetMeshVFormatUnique(pScene->mMeshes[i]);

		if (meshes[i].instance_cnt > 1 && meshes[i].output_id == 0xffffffff) {
			meshes[i].output_id = n++;
			output.push_back(mScene->mMeshes[i]);
		}
	}

	// and process all nodes in the scenegraoh recursively
	ProcessNode(pScene->mRootNode);
	if (!output.size()) {
		throw DeadlyImportError("OptimizeMeshes: No meshes remaining; there's definitely something wrong");
	}

	meshes.clear();
	ai_assert(output.size() <= num_old);

	mScene->mNumMeshes = output.size();
	std::copy(output.begin(),output.end(),mScene->mMeshes);

	if (output.size() != num_old) {
		char tmp[512];
		::sprintf(tmp,"OptimizeMeshesProcess finished. Input meshes: %i, Output meshes: %i",num_old,pScene->mNumMeshes);
		DefaultLogger::get()->info(tmp);
	}
	else DefaultLogger::get()->debug("OptimizeMeshesProcess finished");
}

// ------------------------------------------------------------------------------------------------
// Process meshes for a single node
void OptimizeMeshesProcess::ProcessNode( aiNode* pNode)
{
	for (unsigned int i = 0; i < pNode->mNumMeshes;++i) {
		unsigned int& im = pNode->mMeshes[i];

		if (meshes[im].instance_cnt > 1) {
			im = meshes[im].output_id;
		}
		else  {
			merge_list.clear();
			unsigned int verts = 0, faces = 0;

			// Find meshes to merge with us
			for (unsigned int a = i+1; a < pNode->mNumMeshes;++a) {
				register unsigned int am = pNode->mMeshes[a];
				if (meshes[am].instance_cnt == 1 && CanJoin(im,am,verts,faces)) {

					merge_list.push_back(mScene->mMeshes[am]);
					verts += mScene->mMeshes[am]->mNumVertices;
					faces += mScene->mMeshes[am]->mNumFaces;

					--pNode->mNumMeshes;
					for (unsigned int n = a; n < pNode->mNumMeshes; ++n)
						pNode->mMeshes[n] = pNode->mMeshes[n+1];

					--a;
				}
			}

			// and merge all meshes which we found, replace the old ones
			if (!merge_list.empty()) {
				merge_list.push_back(mScene->mMeshes[im]);

				aiMesh* out;
				SceneCombiner::MergeMeshes(&out,0,merge_list.begin(),merge_list.end());
				output.push_back(out);
			}
			else {
				output.push_back(mScene->mMeshes[im]);
			}
			im = output.size()-1;
		}
	}


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

// ------------------------------------------------------------------------------------------------
// Check whether two meshes can be joined
bool OptimizeMeshesProcess::CanJoin ( unsigned int a, unsigned int b, unsigned int verts, unsigned int faces )
{
	if (meshes[a].vertex_format != meshes[b].vertex_format)
		return false;

	aiMesh* ma = mScene->mMeshes[a], *mb = mScene->mMeshes[b];

	if ((0xffffffff != max_verts && verts+mb->mNumVertices > max_verts) ||
		(0xffffffff != max_faces && faces+mb->mNumFaces    > max_faces)) {
		return false;
	}

	// Never merge unskinned meshes with skinned meshes
	if (ma->mMaterialIndex != mb->mMaterialIndex || ma->HasBones() != mb->HasBones())
		return false;

	// Never merge meshes with different kinds of primitives if SortByPType did already
	// do its work. We would destroy everything again ...
	if (pts && ma->mPrimitiveTypes != mb->mPrimitiveTypes)
		return false;

	// If both meshes are skinned, check whether we have many bones defined in both meshes. 
	// If yes, we can savely join them. 
	if (ma->HasBones()) {
		// TODO
		return false;
	}
	return true;
}

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

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

#endif // !! ASSIMP_BUILD_NO_OPTIMIZEMESHES_PROCESS