[QGIS-Developer] QGIS 3D: navigation questions

[Martin Dobias]

Hi Andreas

On Wed, Dec 13, 2017 at 3:25 PM, Andreas Neumann <a.neumann at carto.net> wrote:
> Hi,
>
> I think I heard several people stating that the navigation in QGIS 3D is too
> fast. Nyall has a PR to slow down navigation when holding the Ctrl-key -
> which unfortunately hadn't been merged to master yet.
>
> To me the question is: when the majority of users think that navigation is
> too fast, shouldn't the default already be slower?

I am easy here - we can make the defaults slower.  To which parts of
navigation do you refer to when you say too fast?
- zooming with mouse wheel
- zooming with right mouse button
- rotating camera with middle mouse button
- moving camera with left mouse button
- moving camera with arrow keys
- rotating camera with shift+arrow keys

Different controls have different constants - or all of them are too fast?


> Other navigation issues I have:
>
> * I did not find a way to lower or raise the altitude of the "camera" while
> staying it the same positions and not changing all the viewing angles (like
> taking the helicopter up and down at the same position). Is there a hidden
> shortcut for that?

As Nyall has already pointed out, this is currently not possible and
there is a ticket to add that.

At some point I would like to do a larger overhaul of the current
camera controller as I do not really like how the camera state is
represented now (camera pointing towards point X,Y at zero elevation
with distance D and given pitch and yaw angles). The current
representation does not make it very easy to implement camera rotation
while not changing its position and other kinds of movements. Another
issue is the assumption that user looks towards a point at zero
elevation, which is not true when using a real terrain, making the
camera rotation behavior far from ideal. It is probably too late to do
some significant changes to the camera controller for 3.0, but it is
on my to-do list for the next release.

I was also thinking of having an advanced mode for controlling camera
- something like a first-person shooter game camera where user could
fly in any direction. Any ideas about how camera controls are welcome!


> * When rotating the whole model (middle mouse button) - how can I determine
> the rotation point? What is the rule for rotating the whole model?

As said above, the camera rotates around point (X, Y, 0) towards which
the camera is looking (keeping the same distance). Currently it does
not use the true terrain altitude for the rotation center.


> Is there any documentation somewhere about how the navigation should work? I

The navigation is described in the 3D QEP in "Camera Control" section:
https://github.com/qgis/QGIS-Enhancement-Proposals/issues/105

> read something about support for keyboard (arrow keys) - but if I use the
> arrow keys, only the main 2D canvas is panned, not the 3D view. Also the
> Shift key, which should be used according to
> https://www.lutraconsulting.co.uk/blog/2017/10/16/buildings-in-qgis3d/ has
> no effect on my machine - maybe another KDE/Plasma issue?

The issue with Shift key when docked has been reported already - I
looked into it briefly but haven't found the culprit yet:
https://issues.qgis.org/issues/17337

Cheers
Martin