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Author Topic:   "controlled" random??
phillipm
Member 		posted 26 October 2003 14:28         Edit/Delete Message   Reply w/Quote
I'm looking for some way to control the behavoir of a random panning feature (other than manually panning each event ... boring!!!) But so far I've been unsuccessful.

What I'm looking for is the equivalent of the [change] object in Max. I want each !Keydown triggered event to come from an obviously different pan placement than the previous one. Initital attempts to limit the random output so that the different pan locations are consistently obvious [example: !KeyDown nextRandom * 4 of: #(0.9 0.75 0.25 0.1)] produce FAR too many instances where the pan position does not change from one to the next.

I think what I need a way of discarding the output of a limited nextRandom in the event that it's the same as the previous one ... and then quickly generating another ... and another ... and another if necessary ... until it's different.

Surely there is a way to do this... yes?!?!

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SSC
Administrator 		posted 27 October 2003 10:47         Edit/Delete Message   Reply w/Quote
How about taking a different approach to achieving the same end:
1. Create a repeating circular pan
2. Sample and hold it at random time intervals

For example, a circular pan that repeats every three seconds would be
(1 repeatingRamp: 3 s) for the Panner Sound
or (1 repeatingFullRamp: 3 s) for the Timeline

To generate a random number from a uniform distribution at random time intervals you could use
1 s randExp random
You could test whether this random number exceeds a threshold and trigger the sample and hold on the following test case:
(1 s randExp random gt: 0)
Put them all together and you get
(1 s randExp random gt: 0) sampleAndHold: ((1 repeatingRamp: 3 s) * 2)

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SSC
Administrator 		posted 27 October 2003 10:49         Edit/Delete Message   Reply w/Quote
Another approach would be to create a long array of random numbers in Smalltalk. Then use countTriggersMod: to step through that array. In this way you could ensure that the positions were different enough from each other to satisfy your criterion.

(BTW, this is the kind of problem that would be perfect for the 'How' section of the kyma•tweaky. If you post it there, I promise to give you an example of how to generate the random array in Smalltalk

[This message has been edited by SSC (edited 27 October 2003).]

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phillipm
Member 		posted 27 October 2003 22:12         Edit/Delete Message   Reply w/Quote
quote:
Originally posted by SSC:
(BTW, this is the kind of problem that would be perfect for the 'How' section of the kyma•tweaky. If you post it there, I promise to give you an example of how to generate the random array in Smalltalk
[/B]

tried to post ot there ... but alas was unsuccessful kept getting error message

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