title: psychopy, changing poligon characteristics with keyboard
body: <p>I need to run a test where the subject is able to rotate a line with the keyboard during the test. </p>
  
  <p>I have been looking a lot, but I have not found a good answer. </p>
  
  <p>So far I have tried this:</p>
  
  <pre><code>p = 0
  polygon = visual.Line(
      win=win,
      name='polygon',
      units='cm', 
      start=(-(2, 0.5)[0]/2.0, 0),
      end=(+(2, 0.5)[0]/2.0, 0),
      ori=p,
      pos=(0, 0),
      lineWidth=1,
      lineColor=[1,1,1],
      lineColorSpace='rgb',
      fillColor=[1,1,1],
      fillColorSpace='rgb',
      opacity=1,
      depth=0.0,
      interpolate=True
  )
  
  while True:
     resp_key = event.waitKeys(keyList=['n','m','return']) 
  
     if resp_key == 'n':
        p = p-1
     elif resp_key == 'm':
        p = p+1
     elif resp_key == 'return':
        break
  </code></pre>
  
  <p>Thanks!</p>