Touch response coordinates

Comments

• sebastiaan

  August 2016

  Hi Fabio,

  That's what the mouse_response item does! When working with a touch screen, a touch is (for most purposes) equivalent to a mouse click.

  Cheers,
  Sebastiaan

  
  
  Check out SigmundAI.eu for our OpenSesame AI assistant!
  
• Fabio

  August 2016

  Thank you, that makes sense. I guess I took "mouse response" quite literally
• Fabio

  May 2017

  I'm sorry to resurrect this thread, but I've only just been able to get back to OpenSesame and I'm now finding it rather tricky to build my experiment.

  The sequence involves a visual stimulus being presented on a sketchpad item while an audio recording plays through a sampler item. That much I can do. However, I then need participants to make a touchscreen response on a new sketchpad, and I need an arrow element to be drawn on it with the apex of the arrow pointing in the direction of the location participants touched on the screen. Think of it as a compass.

  That's where I'm stuck, as I'm not sure how to reference the screen coordinates of the touch response. Any help welcome!
• eduard

  May 2017

  Hi Fabio,

  A touch response is essentially behaving like a mouse response. However, I think it will be rather tricky to get the coordinates of a click by only using the plugin. Probably it is better if you used some inline_scripting, see here.

  The second return value of mouse.get_click()gives you the coordinates of that click. These you can use the draw the arrow into the direction, you want. Will you also need help with that, or is that reasonably clear?

  At any rate, let me know if you need more help.

  Eduard

  
• Fabio

  May 2017

  Hi Eduard,

  Yes, I ended up using an inline script to do this, it now works just as I need it to. Just in case anyone else needs to do something similar, this is my code.

  This part sets up the canvas that participants will use to perform their response. I actually create two canvases, one with an arrow element and one without. That way, when participants make their response, the canvas and arrow will be re-drawn, giving the impression that the arrow has moved. There may be a more elegant way of achieving that effect, but it works for my purposes.

  starting_canvas = canvas()
  my_mouse = mouse()
  
  while True:
          starting_canvas.clear()
          starting_canvas.text("INSTRUCTIONS", center=True, x=0.0, y=372.0, color='white')
          starting_canvas.circle(0, 0, 300, color='white')
          default_canvas = canvas()
          default_canvas.copy(starting_canvas)
          starting_canvas.arrow(0, 0, 0, -300, body_width=0.5, head_width=30, fill = True)
  

  Here I record the time the canvas first appears, and collect the both the time the response is made and the coordinates of the response. These are saved as a tuple, but I also store the X and Y as separate variables, the values of which I will use later to re-draw the arrow. NOTE: The my_mouse.show_cursor line was meant to help during testing of the script on Windows (the actual experiment will run on Android), but it never actually worked. I believe this is a known issue with some backends.

          t0 = starting_canvas.show()
          starting_canvas.show()
          my_mouse.show_cursor(show=True)
          button, position, t1 = my_mouse.get_click()
          var.pos_tuple = position
          var.xpos = position[0]
          var.ypos = position[1]
          var.arrow_length = xy_distance(0, 0, var.xpos, var.ypos)
  

  Here, the touch response triggers the clearing of the canvas, which is replaced by the original one without the arrow. Then a new arrow is drawn on it with the X and Y of participants' responses as the position of the arrow head.

          if position != None:
              starting_canvas.clear()
              default_canvas.show()
              default_canvas.arrow(0, 0, var.xpos, var.ypos, body_width=0.5, head_width=30, fill = True)
              default_canvas.show()
  

  This bit computes the response time, and the angle of the response (i.e. the angle between the 0 degree vector of the circle and the arrow vector).

              var.RT = t1 - t0
              var.rad_angle = math.atan2((0-var.xpos),(0-var.ypos))
              var.deg_angle = math.degrees(var.rad_angle)*-1
              if 0-(var.xpos) > 0:
                  var.deg_angle = 360-math.degrees(var.rad_angle)
              print('angle is (%f)' % (var.deg_angle))
              var.error = var.deg_angle - var.correct
              print('error is (%f)' % (var.error))
              clock.sleep(1000)
              break
  

  I hope this saves someone a lot of trial and error! I'm sure there are more elegant and efficient ways of writing this, so feedback is welcome.
• eduard

  May 2017

  Great! Thanks for sharing.