AssImpModelLoader.cpp

#include "AssImpModelLoader.h"

using namespace std;

bool AssImpModelProgressHandler::Update(float percentage)
{
	emit fileReadProcessed(percentage);
	return true;
}

/*  Functions   */
// Constructor, expects a filepath to a 3D model.
AssImpModelLoader::AssImpModelLoader(QOpenGLShaderProgram* prog) : QObject(), _prog(prog)
{
	initializeOpenGLFunctions();
	_loadingCancelled = false;
	_progHandler = new AssImpModelProgressHandler();
	_importer.SetProgressHandler(_progHandler);
	connect(_progHandler, SIGNAL(fileReadProcessed(float)), this, SLOT(processFileReadProgress(float)));
}

AssImpModelLoader::~AssImpModelLoader()
{
	disconnect(_progHandler, SIGNAL(fileReadProcessed(float)), this, SLOT(processFileReadProgress(float)));
	//delete _progHandler; // causes crash
	_progHandler = nullptr;
}

void AssImpModelLoader::processFileReadProgress(float percentage)
{
	emit fileReadProcessed(percentage);
}

void AssImpModelLoader::cancelLoading()
{
	_loadingCancelled = true;
}

vector<AssImpMesh*> AssImpModelLoader::getMeshes() const
{
	return _meshes;
}

/*  Functions   */
// Loads a model with supported ASSIMP extensions from file and stores the resulting meshes in the meshes vector.
void AssImpModelLoader::loadModel(string path)
{
	_loadingCancelled = false;
	_path = std::string(path);
	_meshes.clear();
	_loadedTextures.clear();
	// Read file via ASSIMP
	_importer.SetPropertyFloat("PP_GSN_MAX_SMOOTHING_ANGLE", 15);
	const aiScene* scene = _importer.ReadFile(path, aiProcess_CalcTangentSpace |
		aiProcess_GenSmoothNormals |
		aiProcess_JoinIdenticalVertices |
		aiProcess_Triangulate |
		aiProcess_GenUVCoords |
		aiProcess_SortByPType);

	// Check for errors
	if (!scene || scene->mFlags == AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode) // if is Not Zero
	{
		_errorMessage = _importer.GetErrorString();
		cout << "ERROR::ASSIMP:: " << _importer.GetErrorString() << endl;
		return;
	}
	// Retrieve the directory path of the filepath
	this->directory = path.substr(0, path.find_last_of('/'));

	// Process ASSIMP's root node recursively
	this->processNode(0, scene->mRootNode, scene);
}

// Processes a node in a recursive fashion. Processes each individual mesh located at the node and repeats this process on its children nodes (if any).
void AssImpModelLoader::processNode(int nodeNum, aiNode* node, const aiScene* scene)
{
	if (_loadingCancelled)
	{
		emit loadingCancelled();
		return;
	}
	// Process each mesh located at the current node
	for (unsigned int i = 0; i < node->mNumMeshes; i++)
	{
		// The node object only contains indices to index the actual objects in the scene.
		// The scene contains all the data, node is just to keep stuff organized (like relations between nodes).
		aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];

		this->_meshes.push_back(this->processMesh(mesh, scene));
	}

	// After we've processed all of the meshes (if any) we then recursively process each of the children nodes
	for (unsigned int i = 0; i < node->mNumChildren; i++)
	{
		if (_loadingCancelled)
		{
			emit loadingCancelled();
			return;
		}
		this->processNode(++nodeNum, node->mChildren[i], scene);
		emit nodeProcessed(nodeNum, node->mNumChildren);
	}
}

AssImpMesh* AssImpModelLoader::processMesh(aiMesh* mesh, const aiScene* scene)
{
	// Data to fill
	vector<Vertex> vertices;
	vector<unsigned int> indices;
	vector<Texture> textures;

	// Walk through each of the mesh's vertices
	int step = 0;
	unsigned int nbVertices = mesh->mNumVertices;
	for (unsigned int i = 0; i < nbVertices; i++)
	{
		step++;
		Vertex vertex;
		glm::vec3 vector; // We declare a placeholder vector since assimp uses its own vector class that doesn't directly convert to glm's vec3 class so we transfer the data to this placeholder glm::vec3 first.

		// Positions
		vector.x = mesh->mVertices[i].x;
		vector.y = mesh->mVertices[i].y;
		vector.z = mesh->mVertices[i].z;
		vertex.Position = vector;

		// Normals
		vector.x = mesh->mNormals[i].x;
		vector.y = mesh->mNormals[i].y;
		vector.z = mesh->mNormals[i].z;
		vertex.Normal = vector;

		// Texture Coordinates
		if (mesh->mTextureCoords[0]) // Does the mesh contain texture coordinates?
		{
			glm::vec2 vec;
			// A vertex can contain up to 8 different texture coordinates. We thus make the assumption that we won't
			// use models where a vertex can have multiple texture coordinates so we always take the first set (0).
			vec.x = mesh->mTextureCoords[0][i].x;
			vec.y = mesh->mTextureCoords[0][i].y;
			vertex.TexCoords = vec;

			// tangent
			if (mesh->mTangents)
			{
				vector.x = mesh->mTangents[i].x;
				vector.y = mesh->mTangents[i].y;
				vector.z = mesh->mTangents[i].z;
				vertex.Tangent = vector;
			}
			// bitangent
			if (mesh->mBitangents)
			{
				vector.x = mesh->mBitangents[i].x;
				vector.y = mesh->mBitangents[i].y;
				vector.z = mesh->mBitangents[i].z;
				vertex.Bitangent = vector;
			}
		}
		else
		{
			if (step == 1)
				vertex.TexCoords = glm::vec2(0.0f, 0.0f);
			else if (step == 2)
				vertex.TexCoords = glm::vec2(1.0f, 0.0f);
			else
			{
				vertex.TexCoords = glm::vec2(0.5f, 1.0f);
				step = 0;
			}
		}
		vertices.push_back(vertex);

		if (i % 100000 == 0)
		{
			emit verticesProcessed(static_cast<float>(i) / nbVertices * 100.0f);
		}
	}

	// Now wak through each of the mesh's faces (a face is a mesh its triangle) and retrieve the corresponding vertex indices.
	for (unsigned int i = 0; i < mesh->mNumFaces; i++)
	{
		aiFace face = mesh->mFaces[i];
		// Retrieve all indices of the face and store them in the indices vector
		for (unsigned int j = 0; j < face.mNumIndices; j++)
		{
			indices.push_back(face.mIndices[j]);
		}
	}

	// Process materials
	GLMaterial mat = GLMaterial::DEFAULT_MAT();
	if (mesh->mMaterialIndex != 0)
	{
		aiMaterial* material = scene->mMaterials[mesh->mMaterialIndex];
		// We assume a convention for sampler names in the shaders. Each diffuse texture should be named
		// as 'texture_diffuseN' where N is a sequential number ranging from 1 to MAX_SAMPLER_NUMBER.
		// Same applies to other texture as the following list summarizes:
		// Diffuse: texture_diffuseN
		// Specular: texture_specularN
		// Normal: texture_normalN

		// ADS Maps
		// 1. diffuse maps
		vector<Texture> diffuseMaps = loadMaterialTextures(material, aiTextureType_DIFFUSE, "texture_diffuse");
		textures.insert(textures.end(), diffuseMaps.begin(), diffuseMaps.end());
		// 2. specular maps
		vector<Texture> specularMaps = loadMaterialTextures(material, aiTextureType_SPECULAR, "texture_specular");
		textures.insert(textures.end(), specularMaps.begin(), specularMaps.end());
		// 3. emissive maps
		vector<Texture> emissiveMaps = loadMaterialTextures(material, aiTextureType_EMISSIVE, "texture_emissive");
		textures.insert(textures.end(), emissiveMaps.begin(), emissiveMaps.end());
		// 4. normal maps
		std::vector<Texture> normalMaps = loadMaterialTextures(material, aiTextureType_HEIGHT, "texture_normal");
		textures.insert(textures.end(), normalMaps.begin(), normalMaps.end());
		// 5. height maps
		std::vector<Texture> heightMaps = loadMaterialTextures(material, aiTextureType_DISPLACEMENT, "texture_height");
		textures.insert(textures.end(), heightMaps.begin(), heightMaps.end());
		// 6. opacity maps
		std::vector<Texture> opacityMaps = loadMaterialTextures(material, aiTextureType_OPACITY, "texture_opacity");
		textures.insert(textures.end(), opacityMaps.begin(), opacityMaps.end());

		// PBR Maps
		// 1. albedo maps
		vector<Texture> albedoPBRMaps = loadMaterialTextures(material, aiTextureType_BASE_COLOR, "albedoMap");
		textures.insert(textures.end(), albedoPBRMaps.begin(), albedoPBRMaps.end());
		// 2. specular maps
		vector<Texture> metalicPBRMaps = loadMaterialTextures(material, aiTextureType_METALNESS, "metallicMap");
		textures.insert(textures.end(), metalicPBRMaps.begin(), metalicPBRMaps.end());
		// 3. roughness maps
		vector<Texture> roughnessPBRMaps = loadMaterialTextures(material, aiTextureType_DIFFUSE_ROUGHNESS, "roughnessMap");
		textures.insert(textures.end(), roughnessPBRMaps.begin(), roughnessPBRMaps.end());
		// 4. emissive maps
		vector<Texture> emissivePBRMaps = loadMaterialTextures(material, aiTextureType_EMISSION_COLOR, "emissiveMap");
		textures.insert(textures.end(), emissivePBRMaps.begin(), emissivePBRMaps.end());
		// 5. normal maps
		std::vector<Texture> normalPBRMaps = loadMaterialTextures(material, aiTextureType_NORMAL_CAMERA, "normalMap");
		textures.insert(textures.end(), normalPBRMaps.begin(), normalPBRMaps.end());
		// 6. AO maps
		std::vector<Texture> aoPBRMaps = loadMaterialTextures(material, aiTextureType_AMBIENT_OCCLUSION, "aoMap");
		textures.insert(textures.end(), aoPBRMaps.begin(), aoPBRMaps.end());

		aiColor3D color(0.f, 0.f, 0.f);
		float opacity = 1.0f;
		material->Get(AI_MATKEY_OPACITY, opacity);
		if (AI_SUCCESS == material->Get(AI_MATKEY_COLOR_AMBIENT, color))
		{
			mat.setAmbient(QVector3D(color.r, color.g, color.b));
		}
		if (AI_SUCCESS == material->Get(AI_MATKEY_COLOR_DIFFUSE, color))
		{
			mat.setDiffuse(QVector3D(color.r, color.g, color.b));
			mat.setAlbedoColor(QVector3D(color.r, color.g, color.b));
		}
		if (AI_SUCCESS == material->Get(AI_MATKEY_COLOR_SPECULAR, color))
		{
			mat.setSpecular(QVector3D(color.r, color.g, color.b));
			bool grayScale = (color.r == color.g && color.g == color.b && color.r == color.b);
			float intensity = 0.2126 * color.r + 0.7152 * color.g + 0.0722 * color.b;
			if (grayScale)	
				mat.setMetalness(intensity > 0.04f ? 0.04f : intensity); // limit to 4% for dielectrics
			else
				mat.setMetalness(intensity);
			mat.setRoughness(1.0f - intensity);
			
		}
		if (AI_SUCCESS == material->Get(AI_MATKEY_COLOR_EMISSIVE, color))
		{
			mat.setEmissive(QVector3D(color.r, color.g, color.b));
		}
		if (AI_SUCCESS == material->Get(AI_MATKEY_OPACITY, opacity))
		{
			mat.setOpacity(opacity);
		}
	}

	// Return a mesh object created from the extracted mesh data
	return new AssImpMesh(_prog, QFileInfo(QString(_path.data())).baseName(), vertices, indices, textures, mat);
}

// Checks all material textures of a given type and loads the textures if they're not loaded yet.
// The required info is returned as a Texture struct.
vector<Texture> AssImpModelLoader::loadMaterialTextures(aiMaterial* mat, aiTextureType type, string typeName)
{
	vector<Texture> textures;

	for (unsigned int i = 0; i < mat->GetTextureCount(type); i++)
	{
		aiString str;
		mat->GetTexture(type, i, &str);

		// Check if texture was loaded before and if so, continue to next iteration: skip loading a new texture
		GLboolean skip = false;

		for (unsigned int j = 0; j < _loadedTextures.size(); j++)
		{
			if (_loadedTextures[j].path == str)
			{
				textures.push_back(_loadedTextures[j]);
				skip = true; // A texture with the same filepath has already been loaded, continue to next one. (optimization)
				break;
			}
		}

		if (!skip)
		{
			// If texture hasn't been loaded already, load it
			Texture texture;
			texture.id = textureFromFile(str.C_Str(), this->directory);
			texture.type = typeName;
			texture.path = str;
			textures.push_back(texture);

			this->_loadedTextures.push_back(texture);  // Store it as texture loaded for entire model, to ensure we won't unnecesery load duplicate textures.
		}
	}

	return textures;
}

unsigned int AssImpModelLoader::textureFromFile(const char* path, string directory)
{
	//Generate texture ID and load texture data
	string filename = string(path);
	filename = directory + '/' + filename;
	unsigned int textureID;
	glGenTextures(1, &textureID);

	QImage texImage;

	if (!texImage.load(QString(filename.c_str())))
	{ // Load first image from file
		qWarning("Could not read image file, using single-color instead.");
		QImage dummy(128, 128, static_cast<QImage::Format>(5));
		dummy.fill(Qt::white);
		texImage = dummy;
	}
	else
	{
		texImage = QGLWidget::convertToGLFormat(texImage); // flipped 32bit RGBA
	}

	// Assign texture to ID
	glBindTexture(GL_TEXTURE_2D, textureID);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texImage.width(), texImage.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, texImage.bits());
	glGenerateMipmap(GL_TEXTURE_2D);

	// Parameters
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glBindTexture(GL_TEXTURE_2D, 0);

	return textureID;
}

QString AssImpModelLoader::getErrorMessage() const
{
	return _errorMessage;
}