assimp/code/GenVertexNormalsProcess.cpp

/*
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Open Asset Import Library (ASSIMP)
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*/

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

#include "AssimpPCH.h"

// 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 AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE property
	configMaxAngle = pImp->GetPropertyFloat(AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE,175.f);
	configMaxAngle = AI_DEG_TO_RAD(std::max(std::min(configMaxAngle,175.0f),0.0f));
}

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

	if (pScene->mFlags & AI_SCENE_FLAGS_NON_VERBOSE_FORMAT)
		throw DeadlyImportError("Post-processing order mismatch: expecting pseudo-indexed (\"verbose\") vertices here");

	bool bHas = false;
	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
	{
		if(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;

	// If the mesh consists of lines and/or points but not of
	// triangles or higher-order polygons the normal vectors
	// are undefined.
	if (!(pMesh->mPrimitiveTypes & (aiPrimitiveType_TRIANGLE | aiPrimitiveType_POLYGON)))
	{
		DefaultLogger::get()->info("Normal vectors are undefined for line and point meshes");
		return false;
	}

	// Allocate the array to hold the output normals
	const float qnan = std::numeric_limits<float>::quiet_NaN();
	pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];

	// Compute per-face normals but store them per-vertex
	for( unsigned int a = 0; a < pMesh->mNumFaces; a++)
	{
		const aiFace& face = pMesh->mFaces[a];
		if (face.mNumIndices < 3)
		{
			// either a point or a line -> no normal vector
			for (unsigned int i = 0;i < face.mNumIndices;++i) {
				pMesh->mNormals[face.mIndices[i]] = aiVector3D(qnan);
			}

			continue;
		}

		const aiVector3D* pV1 = &pMesh->mVertices[face.mIndices[0]];
		const aiVector3D* pV2 = &pMesh->mVertices[face.mIndices[1]];
		const aiVector3D* pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices-1]];
		const 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 = 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)	{
				const aiVector3D& v = pMesh->mNormals[verticesFound[a]];
				if (is_not_qnan(v.x))pcNor += v;
			}
			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;
			}
		}
	}
	// Slower code path if a smooth angle is set. There are many ways to achieve
	// the effect, this one is the most straightforward one.
	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)	{
				const aiVector3D& v = pMesh->mNormals[verticesFound[a]];

				// check whether the angle between the two normals is not too large
				// HACK: if v.x is qnan the dot product will become qnan, too
				//   therefore the comparison against fLimit should be false
				//   in every case. 
				if (v * pMesh->mNormals[i] < fLimit)
					continue;

				pcNor += v;
			}
			pcNew[i] = pcNor.Normalize();
		}
	}

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

	return true;
}