assimp/code/GenFaceNormalsProcess.cpp

/*
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Open Asset Import Library (ASSIMP)
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Copyright (c) 2006-2008, ASSIMP Development Team

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  following disclaimer.

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  derived from this software without specific prior
  written permission of the ASSIMP Development Team.

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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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*/

/** @file Implementation of the post processing step to generate face
* normals for all imported faces.
*/
#include "GenFaceNormalsProcess.h"
#include "../include/DefaultLogger.h"
#include "../include/aiPostProcess.h"
#include "../include/aiMesh.h"
#include "../include/aiScene.h"

using namespace Assimp;

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

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

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

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

	bool bHas = false;
	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
	{
		if(this->GenMeshFaceNormals( pScene->mMeshes[a]))
			bHas = true;
	}
	if (bHas)
	{
		DefaultLogger::get()->info("GenFaceNormalsProcess finished. "
			"Face normals have been calculated");
	}
	else DefaultLogger::get()->debug("GenFaceNormalsProcess finished. "
		"Normals are already there");
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
bool GenFaceNormalsProcess::GenMeshFaceNormals (aiMesh* pMesh)
{
	if (NULL != pMesh->mNormals)return false;

	pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];

	for( unsigned int a = 0; a < pMesh->mNumFaces; a++)
	{
		const aiFace& face = pMesh->mFaces[a];

		aiVector3D* pV1 = &pMesh->mVertices[face.mIndices[0]];
		aiVector3D* pV2 = &pMesh->mVertices[face.mIndices[1]];
		aiVector3D* pV3 = &pMesh->mVertices[face.mIndices[2]];

		aiVector3D pDelta1 = *pV2 - *pV1;
		aiVector3D pDelta2 = *pV3 - *pV1;
		aiVector3D vNor = pDelta1 ^ pDelta2;
		vNor.Normalize();

		//if (face.mIndices[1] > face.mIndices[2])
		//	vNor *= -1.0f;

		for (unsigned int i = 0;i < face.mNumIndices;++i)
		{
			pMesh->mNormals[face.mIndices[i]] = vNor;
		}
	}
	return true;
}