SimScale CAE Forum

False selection in 3D viewer

I regularly get a “false selection” in the 3D viewer, this is where I inadvertently select an item I didn’t intend to select.

I finally nailed down why this is happening.

In “pick faces” mode, if the user rotates the model, starting and ending the rotation on the same face, that face will be selected. I don’t think this is the intended behavior.

This false selection also occurs in “pick volumes” mode, only starting and stopping on the same face will select the entire volume that the face is a part of.

I believe this is because cursor maneuvers in paraview were originally designed with the left mouse doing rotation, middle mouse pan, and right mouse zoom in/out. It is only a matter of change of these patterns to match a CAD program.

In fact, paraview allows rotation by using the middle mouse button while holding down either shift or ctrl. We can just get rid of left mouse rotation leaving it only for patch selection.

This “unintended selection” not only happens with rotation, it also happens with panning and zooming. So using any of the three mouse buttons (not just left click selection) will trigger a false selection.

I actually really like the current mouse button assignments and would prefer not to have to use shift or ctrl. Ideally the UI should distinguish between a geometry move (selection disabled) and a mouse click (selection enabled).

Are you aware of any open-source GUI that distinguishes a geometry move and a mouse click? Could you point me to one?

By distinguish I mean with the same mouse button and without shift/ctrl.

I have read your reply wrong. I guess you were saying there should be a key to enable/disable geometry moves and mouse clicks. This is one of the many solutions I had in mind, but the issue I have encountered with such arrangement is I needed to continuously switch between the two modes. An example is the famous F9 key in ICEM of ANSYS. Most of the time I find the extra shift/ctrl keys reduce my time consumed in front of a computer screen.

Actually, you read me correct the first time. It was my assumption that the UI could distinguish between a click (mouse down and up in the same spot) and a move (mouse down and up in different spots). I guess my assumption was wrong because I can’t find any examples of other CAD programs that get around this problem.

So in summary, all three mouse buttons can be used for selection. Therefore, all three move types (rotate, pan and zoom) will potentially select the underlying geometry (if the move starts and finishes on the same face).

So now I understand the problem I know how to avoid it.

Thanks Dylan for clearing that up for me.

I think I may have found an example of a UI that can make the distinction between a move and a click.

In OnShape, a right mouse click on a face will bring up a context menu, but a right mouse move on a face will rotate the model (no context menu).

So maybe it is possible to move without selecting.

Hi guys. I’ve written about this to the team in the first half of the December. Here is a quotation:

"new model navigation I have spotted this during beta tests, but I thought to myself it was temporary. Now I see it was not. Should it be like this? I mean I am not able to move or rotate a model without selecting anything. (Nearly) Each time I move or rotate I select one surface (the one directly below my mouse cursor). In practice after a few such movements model is well covered in red. Is it correct? (Milad had the same issue yesterday.) There was not anything like this in the previous version. What is more in the last version, right before this big update I noticed that this specific “lag” between navigating and selecting disappeared. So, are you sure that current version is correct?

I am sorry if I am complaining about something unimportant, but the last version before the update was perfect and now I see a step back in this matter."

I refer here to one of Milad’s lectures (drone workshop).


I have not encountered any of the issues reported by you. I believe if you hold down your left mouse button away from any patch, you should be able to rotate without marking it red. A camera view makes it more difficult to freely maneuver in the GUI, but it looks like a parallel projected view will be available with future releases.

Hey guys,

thanks already for the feedback. So actually right now it is in fact the intended behavior that every “mouse-click” event where the “mousedown” and “mouseup” event happen on the same entity triggers a selection. I understand that there are of course cases where this selection was not intended by the user. It is not the easiest task to make changes to the “click”-interaction as it adds a lot of testing effort to make sure everything still works properly and there is the risk that users are used to the old workflow and confused when it suddenly changes, but it would be very helpful to know what you guys think would be the “best” user experience. I also consider it very helpful that all important viewer interactions can be done without the need of using the keyboard! @BenLewis, if I understand that correctly, you would consider the best solution to make the selection event dependent on the “frozen” state of the mouse, so no movement in between? What is your opinion on the right and middle mouse button also triggering selection?

Best Alex

Hi @afischer,

Ideally, if anything is possible, this is what I’d like to see happen.

  • All mouse maneuvers (rotate, pan and zoom) stay as they are.
  • Selection is enabled with a left mouse click only (no move).
  • The context menu is presented with a right mouse click only (no move).
  • Center click only, I have to think about, maybe it could reset the spin center (in addition to double click).

To me this feels more intuitive than the current arrangement. I’ve been using SimScale for a relatively long time and its taken till today to understand why some surfaces “mysteriously” get selected.

Having said that, now that I understand what’s going on, it’s not so bad.

I would ask this question. What advantage does the current arrangement give that it’s worth the confusion to new users?

Or maybe it’s just me. Did others find it annoying that surfaces were unintentionally selected when first learning SimScale?


I don’t find it difficult to detect selected patches, as I usually hide them after I group them. Although I don’t have any problem with the current cursor maneuver settings, the following two features will be very helpful once enabled:

  1. Parallel projection view
  2. Different colours to represent (grouped) patches.
1 Like

To @BenLewis

Under a parallel projected view you will find rotation/zooming very easy and therefore less likely to select unwanted patches.


a quick update on the selection topics. The selection behavior has now been changed to only select entities if clicked upon via a left click, while not performing a navigational operation (so no mouse movement in between).

We are looking into providing the parallel projection view, I’ll keep you updated.

Best Alex


Hi @afischer, thanks for the update. I just gave it a try and I’m really happy with the result. Thanks for getting it done so quickly!

Hey @BenLewis, great to hear that!

Hi @afischer, I’ve been using the updated mouse selection for a while now and it’s great, I do however have one small request. I originally requested that entity selection be via the left mouse click only, I’ve found that I miss the ability to also select via the right mouse click. To reduce the number of clicks required to make a selection I now think the right mouse click should simultaneously select an entity and bring up the context menu. Would it be possible to restore this feature? What do other people think?

Hey @BenLewis,

it would be very easy to switch that and we can do it at any time. In my opinion it is a trade-off between reducing the number of clicks + increasing efficiency and intuitiveness as for me, even after years of using the viewer, it still happened quite often that I right-clicked an already selected entity and had to use then three clicks. It would be very interesting what other people think as I guess we should make as comfortable as possible for most of our users and especially the people using SimScale the most, where of course your opinion counts a lot!

Best Alex