[Newbies] The bouncing sound

Scott Wallace madevu at pacbell.net
Sat Feb 23 22:10:55 UTC 2008

"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  

FWIW here's a script giving good, or at least intuitive, joystick/ 
paddle action:

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-- Scott

On Feb 23, 2008, at 5:30 AM, Herbert K?nig 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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