started on assimp importing and texture stuff

src/ModelLoader.cpp

@@ -0,0 +1,94 @@
+//
+// Created by lbmas on 4/29/2026.
+//
+
+#include <spdlog/spdlog.h>
+
+#include "ModelLoader.h"
+
+#include <assimp/Importer.hpp>
+#include <assimp/postprocess.h>
+#include <assimp/scene.h>
+
+void process_ai_node(aiNode* node, const aiScene* scene, Model* model);
+Mesh process_ai_mesh(aiMesh* aiMesh, const aiScene* scene, Model* model);
+
+std::shared_ptr<Model> ModelLoader::load_from_file(std::string_view _path)
+{
+    Assimp::Importer importer;
+
+    const aiScene* scene = importer.ReadFile(_path.data(),
+                                             /*aiProcess_CalcTangentSpace |*/
+                                             aiProcess_Triangulate | aiProcess_GenSmoothNormals | aiProcess_FlipUVs |
+                                             aiProcess_CalcTangentSpace);
+
+    if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode)
+    {
+        spdlog::error("failed to load model {}: {}", _path, importer.GetErrorString());
+        return nullptr;
+    }
+
+    auto model = std::make_shared<Model>();
+
+    process_ai_node(scene->mRootNode, scene, model.get());
+
+    return model;
+}
+
+void process_ai_node(aiNode* node, const aiScene* scene, Model* model)
+{
+    for (unsigned int i = 0; i < node->mNumMeshes; i++)
+    {
+        aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
+        model->meshes.push_back(process_ai_mesh(mesh, scene, model));
+    }
+}
+
+Mesh process_ai_mesh(aiMesh* aiMesh, const aiScene* scene, Model* model)
+{
+    auto positions = std::vector<float>(aiMesh->mNumVertices * 3);
+    auto uvs = std::vector<float>(aiMesh->mNumVertices * 2);
+    auto normals = std::vector<float>(aiMesh->mNumVertices * 3);
+    auto indices = std::vector<unsigned int>(aiMesh->mNumFaces * 3);
+
+    for (unsigned int i = 0; i < aiMesh->mNumVertices; i++)
+    {
+        auto position = aiMesh->mVertices[i];
+        positions.push_back(position.x);
+        positions.push_back(position.y);
+        positions.push_back(position.z);
+
+        if (aiMesh->HasNormals())
+        {
+            normals.push_back(aiMesh->mNormals[i].x);
+            normals.push_back(aiMesh->mNormals[i].y);
+            normals.push_back(aiMesh->mNormals[i].z);
+        }
+        else
+        {
+            normals.push_back(0);
+            normals.push_back(0);
+            normals.push_back(0);
+        }
+
+        if (aiMesh->HasTextureCoords(0))
+        {
+            uvs.push_back(aiMesh->mTextureCoords[0][i].x);
+            uvs.push_back(aiMesh->mTextureCoords[0][i].y);
+        }
+        else
+        {
+            uvs.push_back(0);
+            uvs.push_back(0);
+        }
+    }
+
+    for(unsigned int i = 0; i < aiMesh->mNumFaces; i++)
+    {
+        const aiFace face = aiMesh->mFaces[i];
+        for(unsigned int j = 0; j < face.mNumIndices; j++)
+            indices.push_back(face.mIndices[j]);
+    }
+
+    return {positions, uvs, normals, indices};
+}