message: gltfpack: Adjust the aggressive simplification threshold
  Instead of checking the source mesh complexity, we now check the target
  mesh complexity - if we're asked to simplify to under 50 triangles the
  sloppy simplification results are likely to be too distorted to bother.
diff: @@ -848,10 +848,11 @@ void simplifyMesh(Mesh& mesh, float threshold, bool aggressive)
  indices.resize(meshopt_simplify(&indices[0], &mesh.indices[0], mesh.indices.size(), positions->data[0].f, vertex_count, sizeof(Attr), target_index_count, target_error));
  mesh.indices.swap(indices);
  - // TODO: if the simplifier got stuck, reindex without normals/tangents and retry
  + // Note: if the simplifier got stuck, we can try to reindex without normals/tangents and retry
  + // For now we simply fall back to aggressive simplifier instead
  // if the mesh is complex enough and the precise simplifier got "stuck", we'll try to simplify using the sloppy simplifier which is guaranteed to reach the target count
  - if (aggressive && mesh.indices.size() > 100 * 3 && mesh.indices.size() > target_index_count)
  + if (aggressive && target_index_count > 50 * 3 && mesh.indices.size() > target_index_count)
  {
  indices.resize(meshopt_simplifySloppy(&indices[0], &mesh.indices[0], mesh.indices.size(), positions->data[0].f, vertex_count, sizeof(Attr), target_index_count));
  mesh.indices.swap(indices);
  