Function parseObjFace

source/MRMesh/MRMeshLoadObj.cpp:316–346

};

void parseObjFace( const std::string_view& str, size_t f, ObjFaces & target )
{
    using namespace boost::spirit::x3;

    int nextVert = target.face2vert[f];
    int nextTexv = target.face2texv[f];
    auto v = [&] ( auto& ctx )
    {
        target.vertices[nextVert++] = _attr( ctx );
    };
    auto vt = [&] ( auto& ctx )
    {
        target.textures[nextTexv++] = _attr( ctx );
    };
    auto vn = [&] ( auto& )
    {
        // normals are not used currently
    };

    [[maybe_unused]] bool r = phrase_parse(
        str.begin(),
        str.end(),
        // NOTE: actions are not being reverted after backtracking
        // https://github.com/boostorg/spirit/issues/378
        ( 'f' >> *( int_[v] >> -( '/' >> ( ( int_[vt] >> -( '/' >> int_[vn] ) ) | ( '/' >> int_[vn] ) ) ) ) ),
        ascii::space
    );
    assert( r );
    assert( nextVert == target.face2vert[f + 1] );
    assert( nextTexv == target.face2texv[f + 1] );
}

Expected<void> parseMtlColor( const std::string_view& str, Vector3f& color )
{