Set origin of window somewhere other than the center

Coding
1

Hi,

I’m trying to create a psychopy.Window with the origin at the bottom of the screen instead of the center–this would make it much easier to implement an experiment I’m building. When I try using the viewPos attribute like this (In IPython 5.3.0 interpreter):

win = visual.Window(size=[500, 500], winType='pyglet', 
                    viewPos=[0,-1], units='norm')

I get this error:

ValueError: operands could not be broadcast together with shapes (4,) (2,)

IPython’s traceback locates the error in psychopy/tools/monitorunittools.pyc. I get the same result if viewPos is set to anything (including [0,0]) except None. I’ve also tried creating a window in a .py script.

I’ve tried searching around and I can’t find anyone else with the same issue. Could you help me with this?

I’m using Psychopy version 1.90.2 in a conda environment with Python 2.7.13 and pyglet 1.2.4.
Thanks for your time!

2

What if you try to define your viewPos in pixels rather than normalized unit (just to be consistent since size is in pix)? Change units=‘pix’ too.

1 Like
3

Thanks, @angjw.aaron, that worked! Is there a way to do this while keeping the units in ‘norm’? My situation is I have an entire experiment built, expecting stimuli positions in the [-1,1] range. It’d be a lot easier to add 1 to each instead of converting each to pixels!

I managed to find another work-around in the meantime, so no worries if that’s not possible!

4

I am afraid that is out of my expertise! I am curious as to why normalized units don’t work properly as well. Perhaps someone else might have an answer to this?

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5

This is all new to me, as I didn’t even know that the origin could be shifted, but have you tried setting the units to norm after the window has been created?

1 Like
6

Just tried it, and unfortunately it didn’t work. :confused: Switching units to norm moved the origin back to the center.

from psychopy import visual
pygame 1.9.4
Hello from the pygame community. https://www.pygame.org/contribute.html

win = visual.Window(size=[500,500], viewPos=[0,-250], units='pix')

win.units = 'norm'

test = visual.TextStim(win, text='hope this works!', pos=[0,1])

test.draw(); win.flip()
Out[6]: 85.47405004501343  # text at top of screen