[Interest] SpaceNavigator 3D input device support

[Christian Gagneraud]

On 07/04/15 19:44, Boudewijn Rempt wrote:
> On Tue, 7 Apr 2015, Christian Gagneraud wrote:
>
>> Hi there,
>>
>> Is anyone aware of a Qt based lib that would provide support for devices
>> like the SpaceNavigator? [1]
>>
>> I'm aware of at least one Qt based app (FreeCAD [2]) that works on
>> Linux, OS X and Windows and which has support for this device. I had a
>> look at the source code, it is not that complicated [3], but there's lot
>> of boilerplate for multi-platform support.
>>
>> So i just wondered if someone out there has a nice Qt lib that is easy
>> to integrate into existing projects or even better a Qt input plugin?
>>
>
> Hm, the space navigator support code in Calligra doesn't have any
> platform boilerplate, but whether that means it works on Windows, I
> don't know -- all our space navigators have disappeared in the mists of
> time.

Hi Boudewijn,

I just had a look at the source code, and indeed, Calligra rely solely 
on libspacenav [1] which AFAIU is *not* multi platform.

Quick comparison between FreeCAD and Calligra:
  - Calligra use only libspnav, Freecad can use either proprietary SDK 
(Windows and Mac) or libspnav (X11)
  - Calligra use a polling thread, which communicate with the main 
thread through signal/slots, the receiver then calls some custom event 
handler of a KoToolBase class instance. FreeCAD uses raw event filtering 
on QApp instance and calls postEvent() on focusWidget()
  - Freecad have some logic to manage event accumulation, flooding and 
flushing (didn't quite understand why and how)
  - Freecad as a built-in "calibrate" feature (not sure how this works)
  - Calligra uses the 2 Space navigator buttons as if they were the 
mouse left/right buttons, Freecad defines them as 2 new sort of buttons
  - Calligra interpret the events as position/rotation, FreeCAD as 
translation/rotation, not sure if it's just semantics here. (libspnav 
uses translation/rotation)
  - Device support in Calligra is done by a KoInputDeviceHandler plugin, 
FreeCAD doesn't use the plugin approach.
  - And last thing, FreeCAD has a nice device configuration Widget, 
Calligra relies on the system/user configuration of the spacenavd 
daemon. spnavcfg is the command that provides a GUI with even more 
controls than what FreeCAD provides.

Both approaches have pros and cons.

Side note: On ubuntu, only 3 stock apps depends on libspnav0: freecad, 
calligra and blender:
$ apt-cache rdepends libspnav0
libspnav0
Reverse Depends:
   libspnav0:i386
   libspnav-dev
   freecad
   calligra-libs
   blender

Googling or DuckDuckGoing reveals more 3D related projects (Qt based or 
not) that supports such as OpenSceneGraph, GoogleEarth, Ogre, ... (Not 
counting professional CAD/EDA Software)

I think it would be very nice if Qt had support for this kind of input 
device. Qt already provides key, mouse, native gesture, tablet and touch 
input events.

Chris

>
>
>> Thx,
>> Chris
>>
>> [1] http://www.3dconnexion.eu/products/spacemouse/spacenavigator.html
>> [2]
>> http://www.freecadweb.org/wiki/index.php?title=3Dconnexion_input_devices
>> [3]
>> https://github.com/FreeCAD/FreeCAD_sf_master/blob/master/src/Gui/GuiApplicationNativeEventAware.h
>>
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