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

All rights reserved.

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* Redistributions of source code must retain the above
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  following disclaimer.

* Redistributions in binary form must reproduce the above
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  derived from this software without specific prior
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*/

/** @file Implementation of the post processing step to generate face
* normals for all imported faces.
*/

// public ASSIMP headers
#include "../include/DefaultLogger.h"
#include "../include/aiPostProcess.h"
#include "../include/aiScene.h"
#include "../include/assimp.hpp"

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

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
GenVertexNormalsProcess::GenVertexNormalsProcess()
{
	this->configMaxAngle = AI_DEG_TO_RAD(175.f);
}

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

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool GenVertexNormalsProcess::IsActive( unsigned int pFlags) const
{
	return (pFlags & aiProcess_GenSmoothNormals) != 0;
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void GenVertexNormalsProcess::SetupProperties(const Importer* pImp)
{
	// get the current value of the property
	this->configMaxAngle = pImp->GetPropertyFloat(AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE,175.f);
	this->configMaxAngle = std::max(std::min(this->configMaxAngle,175.0f),0.0f);
	this->configMaxAngle = AI_DEG_TO_RAD(this->configMaxAngle);
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void GenVertexNormalsProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("GenVertexNormalsProcess begin");

	bool bHas = false;
	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
	{
		if(this->GenMeshVertexNormals( pScene->mMeshes[a],a))
			bHas = true;
	}

	if (bHas)
	{
		DefaultLogger::get()->info("GenVertexNormalsProcess finished. "
			"Vertex normals have been calculated");
	}
	else DefaultLogger::get()->debug("GenVertexNormalsProcess finished. "
		"Normals are already there");
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
bool GenVertexNormalsProcess::GenMeshVertexNormals (aiMesh* pMesh, unsigned int meshIndex)
{
	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[face.mNumIndices-1]];
		aiVector3D vNor = (*pV2 - *pV1) ^ (*pV3 - *pV1).Normalize();

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

	// set up a SpatialSort to quickly find all vertices close to a given position
	// check whether we can reuse the SpatialSort of a previous step.
	SpatialSort* vertexFinder = NULL;
	SpatialSort  _vertexFinder;
	float posEpsilon;
	const float epsilon = 1e-5f;
	if (shared)
	{
		std::vector<std::pair<SpatialSort,float> >* avf;
		shared->GetProperty(AI_SPP_SPATIAL_SORT,avf);
		if (avf)
		{
			std::pair<SpatialSort,float>& blubb = avf->operator [] (meshIndex);
			vertexFinder = &blubb.first;
			posEpsilon = blubb.second;
		}
	}
	if (!vertexFinder)
	{
		_vertexFinder.Fill(pMesh->mVertices, pMesh->mNumVertices, sizeof( aiVector3D));
		vertexFinder = &_vertexFinder;
		posEpsilon = ComputePositionEpsilon(pMesh);
	}
	std::vector<unsigned int> verticesFound;
	aiVector3D* pcNew = new aiVector3D[pMesh->mNumVertices];

	if (configMaxAngle >= AI_DEG_TO_RAD( 175.f ))
	{
		// there is no angle limit. Thus all vertices with positions close
		// to each other will receive the same vertex normal. This allows us
		// to optimize the whole algorithm a little bit ...
		std::vector<bool> abHad(pMesh->mNumVertices,false);

		for (unsigned int i = 0; i < pMesh->mNumVertices;++i)
		{
			if (abHad[i])continue;

			// get all vertices that share this one ...
			vertexFinder->FindPositions( pMesh->mVertices[i], posEpsilon, verticesFound);

			aiVector3D pcNor; 
			for (unsigned int a = 0; a < verticesFound.size(); ++a)
			{
				register unsigned int vidx = verticesFound[a];
				pcNor += pMesh->mNormals[vidx];
			}
			pcNor.Normalize();

			// write the smoothed normal back to all affected normals
			for (unsigned int a = 0; a < verticesFound.size(); ++a)
			{
				register unsigned int vidx = verticesFound[a];
				pcNew[vidx] = pcNor;
				abHad[vidx] = true;
			}
		}
	}
	else
	{
		const float fLimit = cos(configMaxAngle); 
		for (unsigned int i = 0; i < pMesh->mNumVertices;++i)
		{
			// get all vertices that share this one ...
			vertexFinder->FindPositions( pMesh->mVertices[i] , posEpsilon, verticesFound);

			aiVector3D pcNor; 
			for (unsigned int a = 0; a < verticesFound.size(); ++a)
			{
				register unsigned int vidx = verticesFound[a];

				// check whether the angle between the two normals is not too large
				if (pMesh->mNormals[vidx] * pMesh->mNormals[i] < fLimit)
					continue;

				pcNor += pMesh->mNormals[vidx];
			}
			pcNor.Normalize();
			pcNew[i] = pcNor;
		}
	}

	delete[] pMesh->mNormals;
	pMesh->mNormals = pcNew;

	return true;
}