[Newbies] The bouncing sound

[Scott Wallace]

Of course it's the "fence" that allows this second solution to work.   
If your student didn't know about the "fence", I suppose he/she felt  
an urge to use "bounce" in an attempt to contend with the situation at  
the boundary, and that led to the complications we've seen.

This is probably a case where trying things out very early in the  
authoring process would have been helpful.  Trying out the simple  
"forward" script would have revealed that it already worked, with the  
only task remaining being to experiment with different values for the  
scaling factor to get the best "feel," and hence the siren song of  
"bounce" might have been avoided.

Cheers

   -- Scott


On Feb 23, 2008, at 4:56 PM, polishookm wrote:

> Scott, thanks very much for both solutions (and that great  
> explanation about the fence).
>
> The solution you've proposed here is pretty much what the student  
> began with. Except his scaling factor was slightly higher.
>
> I'll see if I can post the project once it's finished.
>
> Ab,
>
> Mark
>
> Scott Wallace wrote:
>> And here's a very different, and perhaps nicer, one-line solution.
>>
>>
>> ------------------------------------------------------------------------
>>
>>
>>
>> Cheers,
>>
>> -- Scott
>>
>>
>> On Feb 23, 2008, at 2:10 PM, Scott Wallace wrote:
>>
>>> "Bounce" is particularly unsuited to this example, because it  
>>> reverses the direction the paddle is "heading" and hence reverses  
>>> the motion brought about by "forward" commands.  This makes it  
>>> hard to retain an intuitive relationship between the joystick and  
>>> the motion of the paddle.
>>>
>>> FWIW here's a script giving good, or at least intuitive, joystick/ 
>>> paddle action:
>>>
>>> <positionPaddle.jpg>
>>>
>>> Cheers,
>>>
>>> -- Scott
>>>
>>>
>>>
>>> On Feb 23, 2008, at 5:30 AM, Herbert König wrote:
>>>
>>>> Hi Mark,
>>>>
>>>> p> That's an interesting observation. Did you, perchance, play  
>>>> with it to
>>>> p> see what a more intuitive (for you) solution would look like?  
>>>> I had the
>>>>
>>>> thanks for asking, that made me try :-))
>>>>
>>>> p> All suggestions welcome ...
>>>>
>>>> Nearly everything i know about Etoys is from the Squeak video  
>>>> DVD. So
>>>> I opened the viewer of the paddle and it has a tile "PongPaddleA's
>>>> heading" which jumps between 0 and 180 when bouncing.
>>>>
>>>> So the simple solution would be to add a "PongPaddleA's heading =  
>>>> 0"
>>>> to the script. I thought I'd just have to drop the tile onto the
>>>> script. But this doesn't work, the script doesn't accept the tile.
>>>>
>>>> This reminded me of several posts on squeak dev that 3.9 is not  
>>>> good
>>>> for etoys. So I guess the Thing to do is follow Scott's advice  
>>>> and use
>>>> a Squeakland image.
>>>>
>>>> Dropping the Project onto a 3.8 image doesn't work, this is also
>>>> known.
>>>>
>>>> So I redid it from Ground up in my 3.8 image using an arrow as the
>>>> pong paddle (guess why). It made the sound but didn't turn on  
>>>> bounce.
>>>> There I learned that one has to drag a tile by the arrow to get it
>>>> into a script.
>>>>
>>>> Then I tried this in 3.9 and in 3.9 the arrow also didn't turn  
>>>> and the
>>>> the trick with fixing the heading of the sketch also worked.
>>>>
>>>> So I proved my accusations on 3.9 unfounded, Sorry 3.9 :-))
>>>>
>>>> Now drop the one who did (against better knowledge) something the
>>>> first time and let the project leader speak up.
>>>>
>>>> What I did with fixing the heading of the paddle in the script  
>>>> was "an
>>>> ugly hack". The price to pay is more uglyness if we ever want to  
>>>> use
>>>> "Paddle turn by Joysticks leftRigt" by having to simulate  
>>>> differential
>>>> geometry by "absolute geometry".
>>>>
>>>> So the way to go is find out what makes the Sketch (the inspector
>>>> shows the paddle is a SketchMorph) misbehave on bounce. Maybe  
>>>> there is
>>>> a reason and then you should use a wide line as your paddle.
>>>>
>>>> Finally:
>>>>
>>>> - Attached is my changed 3.9 Project. --> Not to the list but  
>>>> private
>>>> mail
>>>>
>>>> - Maybe this is off topic here, at least you might get better  
>>>> advice
>>>> on the squeakland mailing list (where I'm not subscribed).
>>>>
>>>> - I'd be curious and willing to comment on further development of  
>>>> the
>>>> project, maybe by private mail unless somebody here also wants to
>>>> follow this.
>>>>
>>>> Cheers
>>>>
>>>> Herbert                            mailto:herbertkoenig at gmx.net
>>>>
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>
> -- 
> 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
>
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