[Newbies] The bouncing sound

Scott Wallace madevu at pacbell.net
Thu Feb 21 07:53:07 UTC 2008

Hi, Mark,

What you're hearing is not a sound associated with the "bounce" but  
rather a sound associated with an object hitting the "fence".

The "fence" is a feature that makes a "forward" command which would  
take an object beyond the edge of its container result in the the  
object's jiggling back into the field of view, accompanied by a  
special "fence" sound.  The intent is to reduce the incidence of  
"runaways" when beginners write scripts using "forward" which rapidly  
take an object beyond an edge of its container, thus making it  

When using "bounce", it's advisable to *disable* the "fence", because  
the interactions between the logic of the two features can produce  
confusing results.

Use the world's "playfield options" menu to disable the fence.

However, without the fence, in your student's example, there seem to  
be situations in which the the paddle overshoots the boundary and  
disappears.  I think you could eliminate these situations by slightly  
reducing the factor used in the paddle's script1.

In the olpc/etoys image, there's an added preference that suppresses  
the fence *sound*, thus allowing the fence feature to be used to keep  
an object within its container's bounds but without the annoyance of  
hearing the "fence" sound.  But this is not in 3.9.

These two features -- a container's "fence" feature and the ability  
for a moving object to request "bounce" -- have always, unhappily,  
been somewhat in conflict.  For the "next" system we expect to have a  
much more harmonious and consistent and understandable way of offering  
such things.

BTW, unless you have a compelling reason to be using 3.9, and  
particularly if tile-scripting is the main focus of your class I  
suggest that you have your students use a Squeakland image rather than  
a 3.9 or 3.10, simply because extensive enhancements, fixes, and  
documentation for tile-scripting ("etoys") are available in the  
Squeakland images.  But if you do decide to switch, it's probably best  
to wait a short while until the "new Squeakland image" gets released.   
This will be based on the OLPC-etoys image, which is the system in  
which all the advances in etoys have been made over the past 18 months  
-- hundreds of bug-fixes, feature-enhancements, performance  
improvement, example projects, tutorials, and other documentation,  
plus a large user community.


   -- Scott

On Feb 20, 2008, at 8:29 PM, polishookm wrote:

> Scott,
> Here's a project file that demonstrates the problem. I'm working in  
> the most recent ver. of Squeak from www.squeak.org (just downloaded  
> a few days ago) .... 3.9-final-7067
> When I activate the script with the object controlled by a joystick,  
> the first few times it hits the top of the world and it's silent -  
> all is well. But at some point, after 3 or 4 or 5 collisions, it's  
> no longer silent.
> All help much appreciated and thanks very much in advance for  
> looking at the project (made by a student in the class I'm teaching).
> Ab,
> Mark
> Scott Wallace wrote:
>> Hi, polishookm,
>> I cannot reproduce the phenomenon you describe in any image I have  
>> close to hand -- not in Squeak 3.9, not in Squeakland3.8-05, and  
>> not in the OLPC etoys image.   (Can anyone else?)
>> What version of Squeak are you using?  If it's 3.10, I'll leave it  
>> for other 3.10 users to track this down, since I don't have a copy  
>> of 3.10 handy.
>> Otherwise, perhaps you could email me a copy of a project of yours  
>> which exhibits this symptom...
>> Cheers,
>> -- Scott
>> On Feb 20, 2008, at 6:38 PM, polishookm wrote:
>>> I"m finding that with
>>> [Rectangle forward by 5]
>>> [Rectangle bounce silence]
>>> the rectangle eventually collides with the top of the world and  
>>> bounces off in the opposite direction - with no sound ... the  
>>> bounce is silent.
>>> However, this script
>>> [Rectangle forward by JoyStick's upDown * 8]
>>> [Rectangle bounce silence]
>>> doesn't allow the Rectangle bounce silently off the edge of the  
>>> world. In this case, when the rectangle  reaches the top of the  
>>> world, it makes a bouncing sound. The exact sound can be selected  
>>> in the [Rectangle bounce silence] tile. But selecting 'silence' as  
>>> the sound doesn't seem to work.
>>> Am I missing something obvious? Shouldn't it be possible to  
>>> silence the bounce?
>>> _______________________________________________
>>> Beginners mailing list
>>> Beginners at lists.squeakfoundation.org
>>> http://lists.squeakfoundation.org/mailman/listinfo/beginners
> -- 
> Mark Polishook, D.M.A.
> Technology Coordinator
> Morehead Hall, Rm 132
> Center for Academic Advising and Adult Learning
> Montclair State University
> Montclair, NJ 07043
> (973)-655-7114
> http://www.montclair.edu/AcademicAdvising/html
> polishookm at mail.montclair.edu
> <GLPong.002.pr>

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