茂之钳
146 lines
4.7 KiB
C++
146 lines
4.7 KiB
C++
#include "vde/foundation/io_obj.h"
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#include <fstream>
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#include <sstream>
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namespace vde::foundation {
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ObjMeshData read_obj(const std::string& filepath) {
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ObjMeshData data;
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std::ifstream file(filepath);
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if (!file) return data;
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std::string line;
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std::string current_material;
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while (std::getline(file, line)) {
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// Trim trailing \r
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if (!line.empty() && line.back() == '\r') line.pop_back();
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if (line.empty() || line[0] == '#') continue;
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std::istringstream iss(line);
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std::string token;
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iss >> token;
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if (token == "v") {
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double x, y, z;
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iss >> x >> y >> z;
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data.vertices.emplace_back(x, y, z);
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}
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else if (token == "vt") {
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double u, v, w = 0.0;
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iss >> u >> v;
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if (iss >> w) { /* 1D/3D texcoord — keep only uv */ }
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data.texcoords.emplace_back(u, v);
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}
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else if (token == "vn") {
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double nx, ny, nz;
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iss >> nx >> ny >> nz;
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data.normals.emplace_back(nx, ny, nz);
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}
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else if (token == "usemtl") {
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iss >> current_material;
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}
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else if (token == "f") {
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std::vector<int> face_v;
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std::vector<int> face_vt;
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std::vector<int> face_vn;
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std::string vertex;
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while (iss >> vertex) {
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// Parse v/vt/vn, v//vn, v/vt formats
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int v_idx = -1;
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int vt_idx = -1;
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int vn_idx = -1;
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// Count slashes
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size_t slash1 = vertex.find('/');
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if (slash1 == std::string::npos) {
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// "v" only
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v_idx = std::stoi(vertex) - 1;
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} else {
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v_idx = std::stoi(vertex.substr(0, slash1)) - 1;
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size_t slash2 = vertex.find('/', slash1 + 1);
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if (slash2 == std::string::npos) {
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// "v/vt"
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vt_idx = std::stoi(vertex.substr(slash1 + 1)) - 1;
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} else {
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// "v/vt/vn" or "v//vn"
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std::string mid = vertex.substr(slash1 + 1, slash2 - slash1 - 1);
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if (!mid.empty()) vt_idx = std::stoi(mid) - 1;
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vn_idx = std::stoi(vertex.substr(slash2 + 1)) - 1;
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}
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}
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face_v.push_back(v_idx);
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face_vt.push_back(vt_idx);
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face_vn.push_back(vn_idx);
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}
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data.faces.push_back(std::move(face_v));
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data.face_texcoords.push_back(std::move(face_vt));
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data.face_normals.push_back(std::move(face_vn));
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data.face_materials.push_back(current_material);
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}
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}
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return data;
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}
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void write_obj(const std::string& filepath, const ObjMeshData& data) {
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std::ofstream file(filepath);
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if (!file) return;
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file.precision(12);
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// Vertices
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for (const auto& v : data.vertices)
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file << "v " << v.x() << " " << v.y() << " " << v.z() << "\n";
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// Texture coordinates
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for (const auto& vt : data.texcoords)
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file << "vt " << vt.x() << " " << vt.y() << "\n";
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// Normals
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bool has_vt = data.has_texcoords();
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bool has_vn = !data.normals.empty();
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for (const auto& n : data.normals)
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file << "vn " << n.x() << " " << n.y() << " " << n.z() << "\n";
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// Faces with material tracking
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std::string current_mtl;
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for (size_t fi = 0; fi < data.faces.size(); ++fi) {
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// Emit material change
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if (fi < data.face_materials.size() && data.face_materials[fi] != current_mtl) {
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current_mtl = data.face_materials[fi];
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if (!current_mtl.empty())
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file << "usemtl " << current_mtl << "\n";
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}
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file << "f";
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const auto& fv = data.faces[fi];
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for (size_t vi = 0; vi < fv.size(); ++vi) {
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file << " " << (fv[vi] + 1); // 0-based → 1-based
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bool wrote_slash = false;
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if (has_vt && fi < data.face_texcoords.size() && vi < data.face_texcoords[fi].size()) {
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int vt = data.face_texcoords[fi][vi];
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if (vt >= 0) {
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if (!wrote_slash) { file << "/"; wrote_slash = true; }
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file << (vt + 1);
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}
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}
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if (has_vn && fi < data.face_normals.size() && vi < data.face_normals[fi].size()) {
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int vn = data.face_normals[fi][vi];
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if (vn >= 0) {
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if (!wrote_slash) file << "/";
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file << "/" << (vn + 1);
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}
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}
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}
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file << "\n";
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}
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}
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} // namespace vde::foundation
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