[visionegg] Re: Constraining SinGrating2D phase with t0_time_sec_absolute = None

Dear all,

Just a follow-up: I have solved the immediate issue by modifying the 
SinGrating2D class to include a boolean parameter, which allows the necessary 
resetting of the phase reference time when set (for example by a controller):

  class SinGrating2D(LuminanceGratingCommon):
  ...        
   parameters_and_defaults = VisionEgg.ParameterDefinition({
          'reset_t0_time':(True,
                ve_types.Boolean,
                "for controlling initial phase"),
  ...
         })
  ...
    def draw(self):
  ...            
              if p.t0_time_sec_absolute is None and not p.ignore_time:
                  p.t0_time_sec_absolute = VisionEgg.time_func()
              if p.reset_t0_time:
                  p.reset_t0_time = False
                  p.t0_time_sec_absolute = VisionEgg.time_func()
  ...

But, I would still be interested in knowing why the solution originally 
suggested using the t0_time_sec_absolute parameter does not work.

Thanks,

Lyle
  ----- Original Message ----- 
  From: Lyle Graham 
  To: visionegg@xxxxxxxxxxxxx 
  Sent: Tuesday, November 08, 2005 2:21 PM
  Subject: [visionegg] Constraining SinGrating2D phase with 
t0_time_sec_absolute = None


  Dear all,

  I am trying to constrain the starting phase of a grating. According to an 
earlier suggestion from Andrew, and following the source code for Gratings.py, 
I tried adding a controller for the t0_time_sec_absolute parameter:
    grating_stimulus = SinGrating2D()

    grating_t0_time_sec_absolute_controller = 
EvalStringController(during_go_eval_string='None',
                                              between_go_eval_string='None',
                                              
eval_frequency=VisionEgg.FlowControl.Controller.TRANSITIONS)

    viewport = Viewport( screen=screen, stimuli=[grating_stimulus] )
    p = Presentation(viewports=[viewport],check_events=1)
    p.add_controller(grating_stimulus,'t0_time_sec_absolute', 
grating_t0_time_sec_absolute_controller)
    p.run_forever()
  Note that when I used the ConstantController instead of the 
EvalStringController, that is:

       initial_controller=ConstantController(during_go_value=None,...)

  I got the following error:
    File "C:\Program 
Files\SurfVision\SurfVisionStimulusSuiteTCP\SurfVisionVisualStimuliSuiteTCP.py",
 line 103, in ?
        eval_frequency=VisionEgg.FlowControl.Controller.TRANSITIONS))
      File "C:\PROGRA~1\Python\lib\site-packages\VisionEgg\FlowControl.py", 
line 874, in __init__
        raise ValueError("Must specify during_go_value")
    ValueError: Must specify during_go_value

  In any event, with the EvalStringController I get the following error:
    File "C:\Program 
Files\SurfVision\SurfVisionStimulusSuiteTCP\SurfVisionVisualStimuliSuiteTCP.py",
 line 194, in ?
        p.add_controller(grating_stimulus,'t0_time_sec_absolute', 
grating_t0_time_sec_absolute_controller)
      File "C:\PROGRA~1\Python\lib\site-packages\VisionEgg\FlowControl.py", 
line 177, in add_controller
        raise TypeError("Attempting to control parameter '%s' of type %s with 
controller that returns type %s"%(
    TypeError: Attempting to control parameter 't0_time_sec_absolute' of type 
Real with controller that returns type None

  Thanks very much for any suggestions.

  Lyle

  Lyle J. Graham
  Laboratory of Neurophysics and Physiology, CNRS UMR 8119
  www.neurophys.biomedicale.univ-paris5.fr/~graham
  UFR Biomédicale de l'Université René Descartes
  45 rue des Saint-Pères, 75006 Paris
   
  Tel: 33 1 42 86 20 92 (Secrétariat: 33 1 42 86 21 38) Fax: 33 1 49 27 90 62



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