Simplest script not working

[vasiliys]

I'm a bit dumbfounded by a tiny script not working the way I would expect:

This simple script should:
1. Turn the screen white on a 'w' press.
2. Turn the screen black on a 'b' press.
3. Turn the screen white, wait half a seconds and turn it black on a 's' press.

For some reason it will not turn it white on the 's' , though it does call the appropriate functions. I have no more ideas on what the issue could be. I hope someone here knows.

I have commented out all code irrelevant to the problem and it persists.

#import sys
import viz
#import vizparallel

viz.go()

def whiteScreen():
	print('White')
	viz.clearcolor(256, 256, 256)

vizact.onkeydown('w', whiteScreen)

def blackScreen():
	print('Black')
	viz.clearcolor(0, 0, 0)

vizact.onkeydown('b', blackScreen)

def sendSignal():
	whiteScreen()
	sendParallel()
	blackScreen()

vizact.onkeydown('s', sendSignal)

def sendParallel(signalCode = 24, delay = 0.5, port = 0x0378):
#	print('Sending code ' + str(signalCode) + ' for ' + str(delay) + ' seconds on port ' + str(port) + ' at tick ' + str(viz.tick()))
#	vizparallel.write( signalCode, port )
	sleep(delay)
#	print('Clearing with a zero at tick ' + str(viz.tick()))
#	vizparallel.write( 0, port )

def sleep(delay):
	start = viz.tick()
	while viz.tick() - start < delay: pass
	return viz.tick() - start

[Jeff]

Try using a task function to control the program flow. In the following code the screen will turn white for 0.5 seconds after the 's' key is pressed:

import viz
import viztask

viz.go()

def whiteScreen():
	print('White')
	viz.clearcolor(256, 256, 256)

vizact.onkeydown('w', whiteScreen)

def blackScreen():
	print('Black')
	viz.clearcolor(0, 0, 0)

vizact.onkeydown('b', blackScreen)

def signalTask():
	while True:
		yield viztask.waitKeyDown('s')
		whiteScreen()
		yield viztask.waitTime(0.5)
		blackScreen()

viztask.schedule(signalTask())

[vasiliys]

Originally Posted by Jeff

Try using a task function to control the program flow....

Thanks Jeff, I figured it out yesterday and made a solution similar to yours (though your method looks neater than mine so I will use it instead).

So from what I understand, though the clearcolor function was executing Vizard was only noting what color to change to. The color would actually change only once control flow was returned to Vizard - which is why it would appear as if only the final color was used.

Thanks for your help!