Changing position of aperture in DriftDemo2.m

1
Hello,

I'm trying to program a grating oscillating within a circular aperture and I've found the DriftDemo2 in PsychDemos particularly useful. However, I noticed that the dstRect is put in the centre of the screen using CenterRect. I tried changing the position of the aperture by redefining dstRect (i.e. giving new coordinates) but then the screen just turned blank. Would anyone give me some advice what I should have done if I want the drifting grating to appear not the centre, but elsewhere on the screen?

Thank you very much.

Best,
Pik Ki
2
It should work. Most likely, you messed up the numbers in the rect. They are [left top right bottom]. Topleft cornner is [0 0].

Xiangrui

--- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@...> wrote:
>
> Hello,
>
> I'm trying to program a grating oscillating within a circular aperture and I've found the DriftDemo2 in PsychDemos particularly useful. However, I noticed that the dstRect is put in the centre of the screen using CenterRect. I tried changing the position of the aperture by redefining dstRect (i.e. giving new coordinates) but then the screen just turned blank. Would anyone give me some advice what I should have done if I want the drifting grating to appear not the centre, but elsewhere on the screen?
>
> Thank you very much.
>
> Best,
> Pik Ki
>
3
Indeed.
E.g., dstRect = CenterRectOnPoint(dstRect, 200, 300);
insted of CenterRect() line would center the grating to pixel position (x,y) = (200, 300).

"help PsychRects"

-mario

--- In psychtoolbox@yahoogroups.com, "xrli2002" <xrli2002@...> wrote:
>
> It should work. Most likely, you messed up the numbers in the rect. They are [left top right bottom]. Topleft cornner is [0 0].
>
> Xiangrui
>
> --- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@> wrote:
> >
> > Hello,
> >
> > I'm trying to program a grating oscillating within a circular aperture and I've found the DriftDemo2 in PsychDemos particularly useful. However, I noticed that the dstRect is put in the centre of the screen using CenterRect. I tried changing the position of the aperture by redefining dstRect (i.e. giving new coordinates) but then the screen just turned blank. Would anyone give me some advice what I should have done if I want the drifting grating to appear not the centre, but elsewhere on the screen?
> >
> > Thank you very much.
> >
> > Best,
> > Pik Ki
> >
>
4
Hi Xiangrui,

Thanks for your reply. That's what I thought as well but I'm pretty sure the coordinates I entered are valid...

Best,
Pik Ki

--- In psychtoolbox@yahoogroups.com, "xrli2002" <xrli2002@...> wrote:
>
> It should work. Most likely, you messed up the numbers in the rect. They are [left top right bottom]. Topleft cornner is [0 0].
>
> Xiangrui
>
> --- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@> wrote:
> >
> > Hello,
> >
> > I'm trying to program a grating oscillating within a circular aperture and I've found the DriftDemo2 in PsychDemos particularly useful. However, I noticed that the dstRect is put in the centre of the screen using CenterRect. I tried changing the position of the aperture by redefining dstRect (i.e. giving new coordinates) but then the screen just turned blank. Would anyone give me some advice what I should have done if I want the drifting grating to appear not the centre, but elsewhere on the screen?
> >
> > Thank you very much.
> >
> > Best,
> > Pik Ki
> >
>
5
Nope, Xiangrui is right, it will work if you don't make a mistake. I assume your psychtoolbox is not outdated by years or something else is seriously broken on your computer.

-mario

--- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@...> wrote:
>
> Hi Xiangrui,
>
> Thanks for your reply. That's what I thought as well but I'm pretty sure the coordinates I entered are valid...
>
> Best,
> Pik Ki
>
> --- In psychtoolbox@yahoogroups.com, "xrli2002" <xrli2002@> wrote:
> >
> > It should work. Most likely, you messed up the numbers in the rect. They are [left top right bottom]. Topleft cornner is [0 0].
> >
> > Xiangrui
> >
> > --- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@> wrote:
> > >
> > > Hello,
> > >
> > > I'm trying to program a grating oscillating within a circular aperture and I've found the DriftDemo2 in PsychDemos particularly useful. However, I noticed that the dstRect is put in the centre of the screen using CenterRect. I tried changing the position of the aperture by redefining dstRect (i.e. giving new coordinates) but then the screen just turned blank. Would anyone give me some advice what I should have done if I want the drifting grating to appear not the centre, but elsewhere on the screen?
> > >
> > > Thank you very much.
> > >
> > > Best,
> > > Pik Ki
> > >
> >
>
6
Thanks Mario, that worked! :D

--- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@...> wrote:
>
> Hi Xiangrui,
>
> Thanks for your reply. That's what I thought as well but I'm pretty sure the coordinates I entered are valid...
>
> Best,
> Pik Ki
>
> --- In psychtoolbox@yahoogroups.com, "xrli2002" <xrli2002@> wrote:
> >
> > It should work. Most likely, you messed up the numbers in the rect. They are [left top right bottom]. Topleft cornner is [0 0].
> >
> > Xiangrui
> >
> > --- In psychtoolbox@yahoogroups.com, "Pik Ki" <pkbeckyho@> wrote:
> > >
> > > Hello,
> > >
> > > I'm trying to program a grating oscillating within a circular aperture and I've found the DriftDemo2 in PsychDemos particularly useful. However, I noticed that the dstRect is put in the centre of the screen using CenterRect. I tried changing the position of the aperture by redefining dstRect (i.e. giving new coordinates) but then the screen just turned blank. Would anyone give me some advice what I should have done if I want the drifting grating to appear not the centre, but elsewhere on the screen?
> > >
> > > Thank you very much.
> > >
> > > Best,
> > > Pik Ki
> > >
> >
>