.. _program_listing_file_Src_GraphicsEngineOpenGL_scene_ObjLoader.cpp:

Program Listing for File ObjLoader.cpp
======================================

|exhale_lsh| :ref:`Return to documentation for file <file_Src_GraphicsEngineOpenGL_scene_ObjLoader.cpp>` (``Src/GraphicsEngineOpenGL/scene/ObjLoader.cpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   module;
   
   #include <algorithm>
   #include <cstddef>
   #include <cstdint>
   #include <cstdlib>
   #include <filesystem>
   #include <iostream>
   #include <sstream>
   #include <stdexcept>
   #include <string>
   #include <unordered_map>
   #include <vector>
   
   #include <glad/glad.h>
   #include <glm/ext/vector_float2.hpp>
   #include <glm/ext/vector_float3.hpp>
   #include <glm/ext/vector_float4.hpp>
   #include <glm/geometric.hpp>
   
   #define TINYOBJLOADER_IMPLEMENTATION
   #include <tiny_obj_loader.h>
   
   #include "hostDevice/host_device_shared.hpp"
   
   module kataglyphis.opengl.obj_loader;
   
   import kataglyphis.opengl.obj_material;
   import kataglyphis.opengl.vertex;
   
   ObjLoader::ObjLoader() = default;
   
   void ObjLoader::load(const std::string &modelFile,
     std::vector<Vertex> &vertices,
     std::vector<unsigned int> &indices,
     std::vector<std::string> &texture_list,
     std::vector<ObjMaterial> &materials,
     std::vector<glm::vec4> &materialIndex)
   {
       tinyobj::ObjReaderConfig const reader_config;
       tinyobj::ObjReader reader;
   
       if (!reader.ParseFromFile(modelFile, reader_config)) {
           if (!reader.Error().empty()) { std::cerr << "TinyObjReader: " << reader.Error(); }
           exit(EXIT_FAILURE);
       }
   
       if (!reader.Warning().empty()) { std::cout << "TinyObjReader: " << reader.Warning(); }
   
       const auto &tol_materials = reader.GetMaterials();
       // texture_list.reserve(tol_materials.size());
   
       if (tol_materials.size() > MAX_MATERIALS) {
           std::cerr << "ObjLoader: We try to load more materials then MAX_MATERIALS is defined!\n";
           exit(EXIT_FAILURE);
       }
   
       // texture at position 0 is plain texture to handle non existing materials
       int texture_id = 1;
   
       std::stringstream texture_base_dir;
       std::filesystem::path const cwd = std::filesystem::current_path();
       texture_base_dir << cwd.string();
       texture_base_dir << RELATIVE_RESOURCE_PATH << "Textures/plain.png";
       texture_list.push_back(texture_base_dir.str());
   
       // we now iterate over all materials to get diffuse textures
       for (const auto &tol_material : tol_materials) {
           const tinyobj::material_t *mp = &tol_material;
           ObjMaterial material;
           material.ambient = glm::vec3(mp->ambient[0], mp->ambient[1], mp->ambient[2]);
           material.diffuse = glm::vec3(mp->diffuse[0], mp->diffuse[1], mp->diffuse[2]);
           material.specular = glm::vec3(mp->specular[0], mp->specular[1], mp->specular[2]);
           material.emission = glm::vec3(mp->emission[0], mp->emission[1], mp->emission[2]);
           material.transmittance = glm::vec3(mp->transmittance[0], mp->transmittance[1], mp->transmittance[2]);
           material.dissolve = mp->dissolve;
           material.ior = mp->ior;
           material.shininess = mp->shininess;
           material.illum = mp->illum;
   
           if (!mp->diffuse_texname.empty()) {
               std::string const relative_texture_filename = mp->diffuse_texname;
               std::string const texture_filename = get_base_dir(modelFile) + "/" + relative_texture_filename;
   
               texture_list.push_back(texture_filename);
   
               material.textureID = texture_id;
               texture_id++;
   
           } else {
               // this means no texture was assigned; we catch it here and assign our
               // plain texture at position 0
               material.textureID = 0;
           }
   
           materials.push_back(material);
       }
   
       // for the case no .mtl file is given place some random standard material ...
       if (tol_materials.empty()) { materials.emplace_back(); }
   
       const auto &attrib = reader.GetAttrib();
       const auto &shapes = reader.GetShapes();
   
       std::unordered_map<Vertex, uint32_t> vertices_map{};
   
       // Loop over shapes
       for (const auto &shape : shapes) {
           // prepare for enlargement
           vertices.reserve(shape.mesh.indices.size() + vertices.size());
           indices.reserve(shape.mesh.indices.size() + indices.size());
   
           // Loop over faces(polygon)
           size_t index_offset = 0;
           for (size_t f = 0; f < shape.mesh.num_face_vertices.size(); f++) {
               auto const fv = static_cast<size_t>(shape.mesh.num_face_vertices[f]);
   
               // Loop over vertices in the face.
               for (size_t v = 0; v < fv; v++) {
                   // access to vertex
                   tinyobj::index_t const idx = shape.mesh.indices[index_offset + v];
                   tinyobj::real_t const vx = attrib.vertices[(3 * static_cast<size_t>(idx.vertex_index)) + 0];
                   tinyobj::real_t const vy = attrib.vertices[(3 * static_cast<size_t>(idx.vertex_index)) + 1];
                   tinyobj::real_t const vz = attrib.vertices[(3 * static_cast<size_t>(idx.vertex_index)) + 2];
                   glm::vec3 const pos = { vx, vy, vz };
   
                   minX = std::min(minX, pos.x);
                   maxX = std::max(maxX, pos.x);
                   minY = std::min(minY, pos.y);
                   maxY = std::max(maxY, pos.y);
                   minZ = std::min(minZ, pos.z);
                   maxZ = std::max(maxZ, pos.z);
   
                   glm::vec3 normals(0.0F);
                   // Check if `normal_index` is zero or positive. negative = no normal
                   // data
                   if (idx.normal_index >= 0 && !attrib.normals.empty()) {
                       tinyobj::real_t const nx = attrib.normals[(3 * static_cast<size_t>(idx.normal_index)) + 0];
                       tinyobj::real_t const ny = attrib.normals[(3 * static_cast<size_t>(idx.normal_index)) + 1];
                       tinyobj::real_t const nz = attrib.normals[(3 * static_cast<size_t>(idx.normal_index)) + 2];
                       normals = glm::vec3(nx, ny, nz);
                   }
   
                   glm::vec3 color(-1.F);
                   if (!attrib.colors.empty()) {
                       tinyobj::real_t const red = attrib.colors[(3 * static_cast<size_t>(idx.vertex_index)) + 0];
                       tinyobj::real_t const green = attrib.colors[(3 * static_cast<size_t>(idx.vertex_index)) + 1];
                       tinyobj::real_t const blue = attrib.colors[(3 * static_cast<size_t>(idx.vertex_index)) + 2];
                       color = glm::vec3(red, green, blue);
                   }
   
                   glm::vec2 tex_coords(0.0F);
                   // Check if `texcoord_index` is zero or positive. negative = no texcoord
                   // data
                   if (idx.texcoord_index >= 0 && !attrib.texcoords.empty()) {
                       tinyobj::real_t const tx = attrib.texcoords[(2 * static_cast<size_t>(idx.texcoord_index)) + 0];
                       // flip y coordinate !!
                       tinyobj::real_t const ty =
                         1.F - attrib.texcoords[(2 * static_cast<size_t>(idx.texcoord_index)) + 1];
                       tex_coords = glm::vec2(tx, ty);
                   }
   
                   Vertex const vert{ pos, normals, color, tex_coords };
   
                   if (!vertices_map.contains(vert)) {
                       vertices_map[vert] = static_cast<uint32_t>(vertices.size());
                       vertices.push_back(vert);
                   }
   
                   indices.push_back(vertices_map[vert]);
               }
   
               index_offset += fv;
   
               // per-face material; face usually is triangle
               // matToTex[shapes[s].mesh.material_ids[f]]
               materialIndex.emplace_back(shape.mesh.material_ids[f], 0.0F, 0.0F, 0.0F);
           }
       }
   
       // precompute normals if no provided
       if (attrib.normals.empty()) {
           for (size_t i = 0; i < indices.size(); i += 3) {
               Vertex &v0 = vertices[indices[i + 0]];
               Vertex &v1 = vertices[indices[i + 1]];
               Vertex &v2 = vertices[indices[i + 2]];
   
               glm::vec3 const n = glm::normalize(glm::cross((v1.position - v0.position), (v2.position - v0.position)));
               v0.normal = n;
               v1.normal = n;
               v2.normal = n;
           }
       }
   }
   
   ObjLoader::~ObjLoader() = default;