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pbr_model.cpp
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pbr_model.cpp
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#include "pbr_model.h"
#include "image.h"
PBRModel::PBRModel(std::string const& path)
{
loadModel(path);
}
// draws the model, and thus all its meshes
void PBRModel::Draw(const ShaderProgram& shader)
{
for (unsigned int i = 0; i < meshes.size(); i++)
meshes[i].Draw(shader);
}
void PBRModel::DrawMaterial(const ShaderProgram& shader)
{
for (unsigned int i = 0; i < meshes.size(); i++)
meshes[i].DrawMaterial(shader);
}
// loads a model with supported ASSIMP extensions from file and stores the resulting meshes in the meshes vector.
void PBRModel::loadModel(std::string const& path)
{
// read file via ASSIMP
Assimp::Importer importer;
const aiScene* scene = importer.ReadFile(path, aiProcess_Triangulate | aiProcess_GenSmoothNormals | aiProcess_FlipUVs);
// check for errors
if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode) // if is Not Zero
{
std::cout << "ERROR::ASSIMP:: " << importer.GetErrorString() << std::endl;
return;
}
// retrieve the directory path of the filepath
directory = path.substr(0, path.find_last_of('/'));
// process ASSIMP's root node recursively
processNode(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 PBRModel::processNode(aiNode* node, const aiScene* scene)
{
// 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.
aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
meshes.push_back(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++)
{
processNode(node->mChildren[i], scene);
}
}
PBRMesh PBRModel::processMesh(aiMesh* mesh, const aiScene* scene)
{
// data to fill
std::vector<PBRVertex> vertices;
std::vector<unsigned int> indices;
std::vector<PBRTexture> textures;
vertices.reserve(mesh->mNumVertices);
indices.reserve(mesh->mNumFaces);
// walk through each of the mesh's vertices
for (unsigned int i = 0; i < mesh->mNumVertices; i++)
{
PBRVertex vertex;
glm::vec3 vector; //placeholder vector since assimp uses its own vector class
// positions
vector.x = mesh->mVertices[i].x;
vector.y = mesh->mVertices[i].y;
vector.z = mesh->mVertices[i].z;
vertex.Position = vector;
// normals
if (mesh->HasNormals())
{
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;
vec.x = mesh->mTextureCoords[0][i].x;
vec.y = mesh->mTextureCoords[0][i].y;
vertex.TexCoords = vec;
}
else
vertex.TexCoords = glm::vec2(0.0f, 0.0f);
vertices.push_back(vertex);
}
// now walk through each of the mesh's faces
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
aiMaterial* material = scene->mMaterials[mesh->mMaterialIndex];
PBRMaterial mat = loadMaterial(material);
// 1. albedo maps
std::vector<PBRTexture> albedoeMaps = loadMaterialTextures(material, aiTextureType_DIFFUSE, "texture_diffuse");
textures.insert(textures.end(), albedoeMaps.begin(), albedoeMaps.end());
// 2. ao maps
std::vector<PBRTexture> aoMaps = loadMaterialTextures(material, aiTextureType_SPECULAR, "texture_ao");
textures.insert(textures.end(), aoMaps.begin(), aoMaps.end());
// 3. metallic maps
std::vector<PBRTexture> metallicMaps = loadMaterialTextures(material, aiTextureType_OPACITY, "texture_metallic");
textures.insert(textures.end(), metallicMaps.begin(), metallicMaps.end());
// 4. normal maps
std::vector<PBRTexture> normalMaps = loadMaterialTextures(material, aiTextureType_HEIGHT, "texture_normal");
textures.insert(textures.end(), normalMaps.begin(), normalMaps.end());
// 5. roughness maps
std::vector<PBRTexture> roughnessMaps = loadMaterialTextures(material, aiTextureType_AMBIENT, "texture_roughness");
textures.insert(textures.end(), roughnessMaps.begin(), roughnessMaps.end());
// return a mesh object created from the extracted mesh data
return PBRMesh(vertices, indices, textures, mat);
}
PBRMaterial PBRModel::loadMaterial(aiMaterial* mat) {
PBRMaterial material;
aiColor3D color(0.f, 0.f, 0.f);
float shininess;
mat->Get(AI_MATKEY_COLOR_DIFFUSE, color);
material.Albedo = glm::vec3(color.r, color.g, color.b);
mat->Get(AI_MATKEY_COLOR_AMBIENT, color);
material.Metallic = color.r;
mat->Get(AI_MATKEY_COLOR_SPECULAR, color);
material.Roughness = color.r;
mat->Get(AI_MATKEY_SHININESS, shininess);
material.Ao = shininess;
return material;
}
// 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.
std::vector<PBRTexture> PBRModel::loadMaterialTextures(aiMaterial* mat, aiTextureType type, std::string typeName)
{
std::vector<PBRTexture> 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
bool skip = false;
for (unsigned int j = 0; j < textures_loaded.size(); j++)
{
if (std::strcmp(textures_loaded[j].path.data(), str.C_Str()) == 0)
{
textures.push_back(textures_loaded[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
PBRTexture texture;
texture.id = TextureFromFile(str.C_Str(), this->directory);
texture.type = typeName;
texture.path = str.C_Str();
textures.push_back(texture);
textures_loaded.push_back(texture); // store it as texture loaded for entire model, to ensure we won't unnecesery load duplicate textures.
}
}
return textures;
}