Re: [vistavrtoolkit-general] Problems with DFN-Node: Could not fetch movements of mouse scrollwheel on linux

[Ingo A. <iar...@ya...>]

I attach a patch to read mouse wheel with non-freeglut under linux. Note
that in theory, one can read any mapped button on X using glut,
including special mouse buttons (I know... the trend is to use just one
button ;)... but one could...)

However, my proposed solution will not work out of the box with windows
glut, and will fail if you, for whatever reasons, have remapped the
wheel under X to different button codes.

There is a patch for win32 glut available here:

http://www.realmtech.net/opengl/glut.php

I noticed that my freeglut (2.6.0-1ubuntu3) does not report mousewheel
callbacks on linux, so the patch might be considered as standard and
have the explicit freeglut dependency removed from the glut mouse driver.

Ingo.

p.s.:
@Daniel: it would be really nice to know which glut version you are using.

@Dominik: as X also maps other buttons, the current code could lead to
corruption, as we do not check the button index (l.105, #29742) when we
write the button value; IMO there should at least be a check/switch-case
whatever.


On 10/04/2012 10:11 PM, Ingo Assenmacher wrote:
> Hi!
> 
> There are some shortcomings on the current implementation as it is in
> Vista with regards to the wheel handling.
> 
> a) if you are using freeglut (which is most often default on Linux), you
> are fine off, but make sure that you compile the library using the
> USE_NATIVE_GLUT=0 preprocessor flag. Check your cmake cache file to see
> the value, os normally the cmake scripts make sure to detect whether you
> have freeglut or the 'only' the normal glut.
> 
> b) depending on your version of glut (here is where the 'luck' part
> starts), it reports mouse wheels as mouse button events. Check if you
> can find GLUT_WHEEL_<UP|DOWN> flags in your glut(.h). If that is the
> case, the Vista implementation is plainly not working good, as it does
> dispatch only the first three buttons and waits for magics to happen to
> the scroll wheel state. (In a nutshell: current glut implementations
> show the wheel as additional button).
> 
> Here is why you see 0 as a value:
> 
> in case the mouse button callback gets called (which happens if you use
> glut and not freeglut and you use the wheel), the mouse driver records
> the current state of the mouse. The right file to look at for your case
> would be
> VistaDeviceDrivers/VistaGlutMouseDriver/VistaGlutMouseDriver.cpp, l.
> 92f). This includes the current state of the variables for the wheel and
> the wheel state. As they are only changed in the case of freeglut
> installed, the state variables do not get updated. Are you sure you see
> "(0,0)" only? And not "(-1,0)"?
> 
> 
> The code, as it is right now can crash, so its good you pointed that
> out. It needs to be fixed. It would be very good to know what version of
> glut you are using and where we can peek at the source.
>