message: fix camera for small models
diff: @@ -26,11 +26,13 @@ ArcballCamera::ArcballCamera(const ospcommon::math::box3f &worldBounds,
  rotation(ospcommon::math::one)
  {
  float diag = length(worldBounds.size());
  +
  zoomSpeed = ospcommon::math::max(diag / 150.0, 0.001);
  - // This works well enough for the models I'm testing
  - if (diag < 1)
  - diag = 1.f/diag;
  + // if Box3f defining wolrd bounds is less than a unit cube
  + // translate along (0, 0, 1)
  + if (diag < 1.7)
  + diag = 1.7f;
  centerTranslation =
  ospcommon::math::AffineSpace3f::translate(-worldBounds.center());
  