wait_for_fixation_start() returns strange things for EyeLink
I have been using the exp.pygaze_eyetracker.sample() function to get the location of the eye and it seems to work well, both with the Advanced dummy (mouse simulation) and with EyeLink 1000. The only issue with it is that if I use default "Uniform coordinates" setting in OpenSesame, I have to correct the coordinates returned by the sample() function like this (for both the dummy and EyeLink):
eyex = eyex - var.width/2
eyey = eyey - var.height/2
Maybe it is possible to fix this somewhere or put it into the documentation? But it's not a big deal, one just needs to be aware of it.
Next I wanted to get the location not just of any gaze position, but of fixation position. So I used the exp.pygaze_eyetracker.wait_for_fixation_start() function, which works well with the advanced dummy (returns a timestamp and a tuple of x and y coordinates, as described in the documentation, and one just needs to adjust them as desribed above). But it does NOT work with EyeLink: it returns a different number of values, and the coordinates are constant and meaningless (-2^15).
Example output from wait_for_fixation_start() for Advanced dummy:
(43009.0, (529, 399))
(43069.0, (526, 400))
(43189.0, (514, 390))
(43239.0, (513, 388))
(43289.0, (513, 387))
(43339.0, (513, 387))
Example output for EyeLink:
(142906.0, 8726187.0, (-32768.0, -32768.0))
(143386.0, 8726667.0, (-32768.0, -32768.0))
(143579.0, 8726859.0, (-32768.0, -32768.0))
(143924.0, 8727205.0, (-32768.0, -32768.0))
(144167.0, 8727447.0, (-32768.0, -32768.0))
(144529.0, 8727809.0, (-32768.0, -32768.0))
(144831.0, 8728111.0, (-32768.0, -32768.0))
This is not influenced by unchecking Uniform coordinates, nor by switching backend to legacy (psycho does not work at all, error Unable to share contexts).
I believe I have the latest SW (OpenSesame 3.1.4, pygaze 0.6.0a21, PyLink 22.214.171.124). The PC runs WinXP and is connected to a dedicated EyeLink computer (where I did not find any settings that could be responsible for this behavior).
Any ideas what could be wrong? Is there a mistake in my setup or in pygaze/pylink/OS? Is there a different way to get a fixation location?