karnkaul / gltf2cpp

A lightweight and modern GLTF parser written in C++20

gltf2cpp

A lightweight and modern GLTF parser written in C++20

Usage

Data structures in gltf2cpp directly reflect the definitions in the GLTF spec, with the slight exception of Accessors: instead of pointing to specific BufferViews, they pre-parse those raw bytes into a typed flat array of primitives. This is stored as a variant in Accessor::data, and aliases like Accessor::UnsignedByte have been provided for convenience (to use as arguments for visitor callbacks). In most cases you won't even need to bother further parsing this data, as a mesh primitive's geometry contains pre-parsed positions, normals, UVs, RGBs, tangents, and indices. Joints and weights may be added in future versions.

// obtain root node
auto root = gltf2cpp::parse("path/to/asset.gltf");
if (!root) { /* handle error */ }
// store materials
for (auto const& material : root.materials) {
  // store textures
  if (material.pbr.base_color_texture) {
    auto const& texture = root.textures[material.pbr.base_color_texture->texture];
    auto const& image = root.images[texture.source];
    auto const* sampler = texture.sampler ? &root.samplers[*texture.sampler] : nullptr;
    add_texture(image.bytes.span(), sampler, texture.linear);
  }
  add_material(material);
}
// store meshes
for (auto const& mesh : root.meshes) {
  auto my_mesh = MyMesh{};
  for (auto const& primitive : mesh.primitives) {
    auto geometry = make_geometry(primitive.geometry.positions,
      primitive.geometry.tex_coords, primitive.geometry.normals, primitive.indices);
    my_mesh.add_primitive(std::move(geometry), get_material(primitive.material));
  }
  add_mesh(std::move(my_mesh));
}

Requirements

• CMake 3.18+
• C++20 (GCC 10.x compatible)

Setup

1. Obtain source via cloning, git submodules, CMake FetchContent, etc.
2. (Optional) Add custom djson to CMake build tree.
3. Add gltf2cpp to CMake build tree via add_subdirectory.
   1. gltf2cpp will fetch djson if the target is not already in the build tree.
4. Link to desired target via target_link_libraries(foo PRIVATE gltf2cpp::gltf2cpp).
5. Use #include <gltf2cpp/gltf2cpp.hpp> to import the library.