[visionegg] Re: mostly grating related...
- From: Andrew Straw <andrew.straw@xxxxxxxxxxxxxxx>
- To: visionegg@xxxxxxxxxxxxx
- Date: Fri, 22 Aug 2003 09:56:45 +0930
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Markus Bongard wrote:
Besides that I'm trying to implement two other things: First one is
that I like to define the bars by giving a x,y-center which is crossed
from a given angle on a given path length. I suppose besides more
Python this brings me deep into OpenGL programming, right?
I'm not sure that I understand exactly what you mean, but I'm not sure
why you'd need OpenGL programming, probably just a big of trig. Also,
one of the big changes for the 0.9.5 release will be use of "anchors"
for specifying positions, which should simplify things. (Get the
bleeding edge release for a preview, if you're not using that already.)
Second, I like to have flashes - maybe someone has done something in
both directions already. (?)
I'm not sure what you mean by this, but all (or most) stimuli have an
on parameter, and the Screen class has a bgcolor parameter -- you can
produce flashes this way.
In the meantime I have a much simpler labview interface for the tcp/ip
controlled grating and started to implement Python in a external
labview module. We'll see how this works out. =8) <- I will put up
some webpage which can be linked from the visionegg side.
Fantastic. (I recently fixed some bugs in the TCPControllers module
for 0.9.5 series -- I don't think they're in the latest "bleeding edge"
tarball, but they're certainly in CVS.) You're welcome to add any
links to the wiki pages.
Additionally some question: if I display a greating with a constant
spatial and temporal frequency several times in a sequence <- the
phase display (read the location of the mini- and maxima intensity of
the grating) is spatially not always the same.
You're right -- this is by design, although I'm open to suggestions on
how to do it better. Here's a bit of background: in order to compute
phase of a grating based purely on temporal frequency (in other words,
with no initial condition given for phase), some arbitrary initial
phase must be picked. This is done just once for each instance of
SinGrating2D using an "absolute" time -- not relative to the onset of
trials. (This allows a grating to continue moving between trials to,
for example, maintain a particular state of adaptation in motion
sensitive neurons.) To make the initial phase of the grating the same
between grating presentations, you could make a new instance of
SinGrating2D each time you needed a new grating with that same starting
phase. Alternatively (and more efficiently), you could reset the
t0_time_sec_absolute parameter to None, which will cause this value to
be set the next time it is drawn. In all cases, the phase_at_t0
parameter controls the initial phase at this "t0". Finally, in 0.9.5,
you can set the ignore_time parameter to True and control phase purely
with the phase_at_t0 parameter.
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