assimp/code/FindDegenerates.cpp

/*
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Open Asset Import Library (ASSIMP)
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*/

/** @file Implementation of the DeterminePTypeHelperProcess and
 *  SortByPTypeProcess post-process steps.
*/

#include "AssimpPCH.h"

// internal headers
#include "ProcessHelper.h"
#include "FindDegenerates.h"

using namespace Assimp;

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

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

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

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void FindDegeneratesProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("FindDegeneratesProcess begin");
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
	{
		aiMesh* mesh = pScene->mMeshes[i];
		mesh->mPrimitiveTypes = 0;

		unsigned int deg = 0;
		for (unsigned int a = 0; a < mesh->mNumFaces; ++a)
		{
			aiFace& face = mesh->mFaces[a];
			bool first = true;

			// check whether the face contains degenerated entries
			for (register unsigned int i = 0; i < face.mNumIndices; ++i)
			{
				for (register unsigned int a = i+1; a < face.mNumIndices; ++a)
				{
					if (mesh->mVertices[face.mIndices[i]] == mesh->mVertices[face.mIndices[a]])
					{
						// we have found a matching vertex position
						// remove the corresponding index from the array
						for (unsigned int m = a; m < face.mNumIndices-1; ++m)
						{
							face.mIndices[m] = face.mIndices[m+1];
						}
						--a;
						--face.mNumIndices;

						// NOTE: we set the removed vertex index to an unique value
						// to make sure the developer gets notified when his
						// application attemps to access this data.
						face.mIndices[face.mNumIndices] = 0xdeadbeef;

						if(first)
						{
							++deg;
							first = false;
						}
					}
				}
			}

			// We need to update the primitive flags array of the mesh.
			// Unfortunately it is not possible to execute
			// FindDegenerates before DeterminePType. The latter does
			// nothing if the primitive flags have already been set by
			// the loader - our changes would be ignored. Although
			// we could use some tricks regarding - i.e setting 
			// mPrimitiveTypes to 0 in every case - but this is the cleanest 
			//  way and causes no additional dependencies in the pipeline.
			switch (face.mNumIndices)
			{
			case 1u:
				mesh->mPrimitiveTypes |= aiPrimitiveType_POINT;
				break;
			case 2u:
				mesh->mPrimitiveTypes |= aiPrimitiveType_LINE;
				break;
			case 3u:
				mesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
				break;
			default:
				mesh->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
				break;
			};
		}
		if (deg)
		{
			char s[64];
			itoa10(s,deg); 
			DefaultLogger::get()->warn(std::string("Found ") + s + " degenerated primitives");
		}
	}
	DefaultLogger::get()->debug("FindDegeneratesProcess finished");
}