message: Initialize arcballCamera early so that .sg files load without crashing
diff: @@ -21,6 +21,9 @@ BatchContext::BatchContext(StudioCommon &_common)
  : StudioContext(_common), optImageSize(_common.defaultSize)
  {
  frame->child("scaleNav").setValue(1.f);
  + // Initialize the Arcball
  + arcballCamera.reset(
  + new ArcballCamera(frame->child("world").bounds(), optImageSize));
  }
  void BatchContext::start()
  @@ -45,6 +48,7 @@ void BatchContext::start()
  std::cout << "..rendering animation!" << std::endl;
  renderAnimation();
  } else if (!cameraStack.empty()) {
  + std::cout << "..using cams.json camera stack" << std::endl;
  for (auto &cs : cameraStack) {
  arcballCamera->setState(cs);
  updateCamera();
  