Tiny obj loader

Tiny but poweful single file wavefront obj loader written in C++. No dependencies except for C++ STL. It can parse over 10M polygons with moderate memory and time.

A great .obj loader for embedding into your (global illumination) renderer ;-)

http://syoyo.github.io/tinyobjloader/

Features

• Groups
• Indices
• Vertices
• Texcoords
• Normals
• Materials
  • Per-face materials.
  • Unknown material attributes are treated as key-value.

Example

tinyobjloader can successfully load the Rungholt scene with 6M triangles.
Source: http://graphics.cs.williams.edu/data/meshes.xml

Usage

First, load your mesh from file, storing the shapes and materials separately.

std::string inputfile = "cornell_box.obj";
std::vector shapes;
std::vector materials;

std::string err = tinyobj::LoadObj(shapes, materials, inputfile.c_str());

if (!err.empty()) {
  std::cerr << err << std::endl;
  exit(1);
}

std::cout << "# of shapes    : " << shapes.size() << std::endl;
std::cout << "# of materials : " << materials.size() << std::endl;

Now that you have loaded the shape and material data from file, you can iterate through each vector to get the information that you need.

Each shape will contain vertex indices, positions, normals, UV coordinates and per-face material IDs.

for (size_t i = 0; i < shapes.size(); i++) {
  printf("shape[%ld].name = %s\n", i, shapes[i].name.c_str());
  printf("Size of shape[%ld].indices: %ld\n", i, shapes[i].mesh.indices.size());
  printf("Size of shape[%ld].material_ids: %ld\n", i, shapes[i].mesh.material_ids.size());
  assert((shapes[i].mesh.indices.size() % 3) == 0);
  for (size_t f = 0; f < shapes[i].mesh.indices.size() / 3; f++) {
    printf("  idx[%ld] = %d, %d, %d. mat_id = %d\n", f, shapes[i].mesh.indices[3*f+0], shapes[i].mesh.indices[3*f+1], shapes[i].mesh.indices[3*f+2], shapes[i].mesh.material_ids[f]);
  }

  printf("shape[%ld].vertices: %ld\n", i, shapes[i].mesh.positions.size());
  assert((shapes[i].mesh.positions.size() % 3) == 0);
  for (size_t v = 0; v < shapes[i].mesh.positions.size() / 3; v++) {
    printf("  v[%ld] = (%f, %f, %f)\n", v,
      shapes[i].mesh.positions[3*v+0],
      shapes[i].mesh.positions[3*v+1],
      shapes[i].mesh.positions[3*v+2]);
  }
}

The per-face material IDs can be used to reference the materials in the materials vector.

for (size_t i = 0; i < materials.size(); i++) {
  printf("material[%ld].name = %s\n", i, materials[i].name.c_str());
  printf("  material.Ka = (%f, %f ,%f)\n", materials[i].ambient[0], materials[i].ambient[1], materials[i].ambient[2]);
  printf("  material.Kd = (%f, %f ,%f)\n", materials[i].diffuse[0], materials[i].diffuse[1], materials[i].diffuse[2]);
  printf("  material.Ks = (%f, %f ,%f)\n", materials[i].specular[0], materials[i].specular[1], materials[i].specular[2]);
  printf("  material.Tr = (%f, %f ,%f)\n", materials[i].transmittance[0], materials[i].transmittance[1], materials[i].transmittance[2]);
  printf("  material.Ke = (%f, %f ,%f)\n", materials[i].emission[0], materials[i].emission[1], materials[i].emission[2]);
  printf("  material.Ns = %f\n", materials[i].shininess);
  printf("  material.Ni = %f\n", materials[i].ior);
  printf("  material.dissolve = %f\n", materials[i].dissolve);
  printf("  material.illum = %d\n", materials[i].illum);
  printf("  material.map_Ka = %s\n", materials[i].ambient_texname.c_str());
  printf("  material.map_Kd = %s\n", materials[i].diffuse_texname.c_str());
  printf("  material.map_Ks = %s\n", materials[i].specular_texname.c_str());
  printf("  material.map_Ns = %s\n", materials[i].normal_texname.c_str());
  std::map::const_iterator it(materials[i].unknown_parameter.begin());
  std::map::const_iterator itEnd(materials[i].unknown_parameter.end());
  for (; it != itEnd; it++) {
    printf("  material.%s = %s\n", it->first.c_str(), it->second.c_str());
  }
  printf("\n");
}

Notes

• Polygons are converted into triangles.
• You must specify the directory location of your material file as the 4th parameter of LoadObj() if your materials are not in the working directory of the application.
• Example:LoadObj(shapes, materials, inputfile.c_str(), "/materials")