OBJLoader.h

#ifndef __OBJLoader_h__
#define __OBJLoader_h__

#include <string>
#include "Logger.h"
#include "StringTools.h"
#include <array>

namespace Utilities
{
	/** \brief Struct to store the position and normal indices
	*/
	struct MeshFaceIndices
	{
		std::array<int, 3> posIndices;
		std::array<int, 3> texIndices;
		std::array<int, 3> normalIndices;
	};

	/** \brief Read for OBJ files. 
	*/
	class OBJLoader
	{
	public:
		using Vec3f = std::array<float, 3>;
		using Vec2f = std::array<float, 2>;

		/** This function loads an OBJ file.
		  * Only triangulated meshes are supported.
		  */

		static void loadObj(const std::string &filename, std::vector<Vec3f> *x, std::vector<MeshFaceIndices> *faces, std::vector<Vec3f> *normals, std::vector<Vec2f> *texcoords, const Vec3f &scale)
		{
			LOG_INFO << "Loading " << filename;
			
			std::ifstream filestream;
			filestream.open(filename.c_str());
			if (filestream.fail())
			{
				LOG_ERR << "Failed to open file: " << filename;
				return;
			}

			std::string line_stream;
			bool vt = false;
			bool vn = false;

			std::vector<std::string> pos_buffer;
			std::vector<std::string> f_buffer;

			while (getline(filestream, line_stream))
			{
				std::stringstream str_stream(line_stream);
				std::string type_str;
				str_stream >> type_str;

				if (type_str == "v")
				{
					Vec3f pos;
					pos_buffer.clear();
					std::string parse_str = line_stream.substr(line_stream.find("v") + 1);
					StringTools::tokenize(parse_str, pos_buffer);
					for (unsigned int i = 0; i < 3; i++)
						pos[i] = stof(pos_buffer[i]) * scale[i];

					x->push_back(pos);
				}
				else if (type_str == "vt")
				{
					if (texcoords != nullptr)
					{
						Vec2f tex;
						pos_buffer.clear();
						std::string parse_str = line_stream.substr(line_stream.find("vt") + 2);
						StringTools::tokenize(parse_str, pos_buffer);
						for (unsigned int i = 0; i < 2; i++)
							tex[i] = stof(pos_buffer[i]);

						texcoords->push_back(tex);
						vt = true;
					}
				}
				else if (type_str == "vn")
				{
					if (normals != nullptr)
					{
						Vec3f nor;
						pos_buffer.clear();
						std::string parse_str = line_stream.substr(line_stream.find("vn") + 2);
						StringTools::tokenize(parse_str, pos_buffer);
						for (unsigned int i = 0; i < 3; i++)
							nor[i] = stof(pos_buffer[i]);

						normals->push_back(nor);
						vn = true;
					}
				}
				else if (type_str == "f")
				{
					MeshFaceIndices faceIndex;
					if (vn && vt)
					{
						f_buffer.clear();
						std::string parse_str = line_stream.substr(line_stream.find("f") + 1);
						StringTools::tokenize(parse_str, f_buffer);
						for (int i = 0; i < 3; ++i)
						{
							pos_buffer.clear();
							StringTools::tokenize(f_buffer[i], pos_buffer, "/");
							faceIndex.posIndices[i] = stoi(pos_buffer[0]) - 1;
							faceIndex.texIndices[i] = stoi(pos_buffer[1]) - 1;
							faceIndex.normalIndices[i] = stoi(pos_buffer[2]) - 1;
						}
					}
					else if (vn)
					{
						f_buffer.clear();
						std::string parse_str = line_stream.substr(line_stream.find("f") + 1);
						StringTools::tokenize(parse_str, f_buffer);
						for (int i = 0; i < 3; ++i)
						{
							pos_buffer.clear();
							StringTools::tokenize(f_buffer[i], pos_buffer, "/");
							faceIndex.posIndices[i] = stoi(pos_buffer[0]) - 1;
							faceIndex.normalIndices[i] = stoi(pos_buffer[1]) - 1;
						}
					}
					else if (vt)
					{
						f_buffer.clear();
						std::string parse_str = line_stream.substr(line_stream.find("f") + 1);
						StringTools::tokenize(parse_str, f_buffer);
						for (int i = 0; i < 3; ++i)
						{
							pos_buffer.clear();
							StringTools::tokenize(f_buffer[i], pos_buffer, "/");
							faceIndex.posIndices[i] = stoi(pos_buffer[0]) - 1;
							faceIndex.texIndices[i] = stoi(pos_buffer[1]) - 1;
						}
					}
					else
					{
						f_buffer.clear();
						std::string parse_str = line_stream.substr(line_stream.find("f") + 1);
						StringTools::tokenize(parse_str, f_buffer);
						for (int i = 0; i < 3; ++i)
						{
							faceIndex.posIndices[i] = stoi(f_buffer[i]) - 1;
						}
					}
					faces->push_back(faceIndex);
				}
			}
			filestream.close();
		}

	};
}
 
#endif