message: fix batch mode camera selection
diff: #include "sg/renderer/MaterialRegistry.h"
  #include "sg/visitors/Commit.h"
  #include "sg/visitors/PrintNodes.h"
  +#include "sg/camera/Camera.h"
  // rkcommon
  #include "rkcommon/utility/SaveImage.h"
  // json
  @@ -196,8 +197,14 @@ void BatchContext::render()
  frame->createChild("renderer", "renderer_" + optRendererTypeStr);
  if (!cameraDef)
  frame->createChild("camera", "camera_" + optCameraTypeStr);
  - else
  - frame->add(cameras[cameraDef - 1]);
  + else {
  + // simply adding a new camera to frame does not work
  + auto newCamera = cameras[cameraDef - 1]->nodeAs<sg::Camera>();
  + auto &camera =
  + frame->createChildAs<sg::Camera>("camera", newCamera->subType());
  + for (auto &c : newCamera->children())
  + camera.add(c.second);
  + }
  baseMaterialRegistry->updateMaterialList(optRendererTypeStr);
  @@ -271,7 +278,10 @@ void BatchContext::render()
  camera["up"] = up;
  }
  + if(camera.hasChild("stereoMode"))
  camera["stereoMode"] = optStereoMode;
  +
  + if(camera.hasChild("interpupillaryDistance"))
  camera["interpupillaryDistance"] = optInterpupillaryDistance;
  frame->child("navMode") = false;
  