message: assume single mip when "mipPositions" is empty
diff: @@ -40,6 +40,25 @@ void legacy_populateMips(
  bool generateMipMaps) {
  uint32 width = static_cast<uint32>(image.width);
  uint32 height = static_cast<uint32>(image.height);
  +
  + if (image.mipPositions.empty()) {
  + // Only the full image is available.
  + FTexture2DMipMap* pMip = new FTexture2DMipMap();
  + platformData.Mips.Add(pMip);
  + pMip->SizeX = width;
  + pMip->SizeY = height;
  +
  + pMip->BulkData.Lock(LOCK_READ_WRITE);
  + void* pDest =
  + pMip->BulkData.Realloc(static_cast<int64>(image.pixelData.size()));
  +
  + FMemory::Memcpy(pDest, image.pixelData.data(), image.pixelData.size());
  +
  + pMip->BulkData.Unlock();
  +
  + return;
  + }
  +
  for (const CesiumGltf::ImageCesiumMipPosition& mipPos : image.mipPositions) {
  FTexture2DMipMap* pMip = new FTexture2DMipMap();
  platformData.Mips.Add(pMip);
  