Dynamic increasing of image scale within each trial

Eris

Hi All,
I am really really new in opensesame, and i am trying to not be biased by my previous knowledge about experimental software, but it is hard.
here is my problem. I am trying to run a kind of BART experiment, in which the the balloon inflates at random speed without key pressing. So i need to dinamycally increase the scale of the image within each trial.
Any suggestion?

Thank you!

eduard

Hi,

Simple inline_scipt example:

cv = canvas() # create a canvas
kb = keyboard(timeout = 2) # create a keyboard

start_r = 10 # initial radius
rate = 100 # rate of increase

cv.circle(0,0,start_r, fill =True) # draw a balloon
t0 = clock.time() # starting time
while True: 
    cv.show() # show the canvas
    k,t = kb.get_key() # stop loop with keypress
    if k != None:
        break
    if (t-t0) >  rate: 
        r += 2
        cv.clear() # wipe the canvas
        cv.circle(0,0,start_r, fill =True) # draw a balloon
        t0= clock.time() # reset timer

Does this make sense?

Eduard

Eris

It does if i draw the baloon, but I have to use an image, so basically I have to dinamically zoom in or out the image, using different speed rates.

eduard

Well, then use the image draw function with its scale parameter: http://osdoc.cogsci.nl/3.1/manual/python/canvas/#function-canvas46image40fname-centertrue-xnone-ynone-scalenone41

Eduard

Eris

Hi eduard,
I have tried to use canvans.image function, but it still doesn't work for me since the canvas. image do not allowed to present any other stimuli in the meanwhile.
So I am trying in this way, I create a sketchpad with all the images that i want to present at the same moment, and then I set the scale of the balloon image as a variable , balloon_size.
The problem is that the var. balloon_size now is a fixed number (i.e. a number that doesn't change its value with time), there is any way to define var. balloon_size Value as a function of time? Exactly like you did in your example for radius? Like for example increase rate of 0.5 every 100 ms?

Thank you

eduard

Hi Eris,

If you have the scale variable defined in your looptable you, can access it in the sketchpad with [scale].

However, I still strongly recommend you implement that problem in an inline_script, simply because to make it work with sketchpads it is more difficult to get the experience exactly like you want it.

I have tried to use canvans.image function, but it still doesn't work for me since the canvas. image do not allowed to present any other stimuli in the meanwhile.

That isn't true. You can draw multiple images on to the canvas. As long as the bigger one doesn't cover the smaller, you should be able to see all of them. If you give me a few example images and a detailed description of how the stimuli should look like, I can make a quick example for you.

Eduard