[etoys-dev] SQ-94 - Flip and Tumble

Steve Thomas sthomas1 at gosargon.com
Tue Aug 17 07:46:59 EDT 2010


Congratulations!!! You have just solved a problem that has frustrated kids
all over! (okay the problem was solved already but no one I know other than
you knew the solution).

For whatever reason kids love to make fish tanks (just look

And every kid I have seen try and do this runs into the same problem. When
the fish gets to the end of the tank it "swims" out of the tank.  Well this
is nice because it leads them to discover (either through the help guides or
by bugging the teacher to find out) about the bounce tile.  This leads to
the problem that the When you paint a fish and it bounces off the walls it
looks like it swimming upside down.  The kids usually come up with a
solution that they have to draw the fish in a certain way so that even
though the graphic "flipped" you can't tell.  But by setting the "rotation
style" you have solve the problem and you can draw assymetrical fish and
that "swim properly"

My description is probably hard to follow so here is a test for all your
Fish loving Etoy fans.

   1. Draw a fish on the screen.
   2. Bring up its halo and create a script with "forward by 5" then run it
      1. Is it swimming in the correct direction?
      2. If not, play with the heading and "forward direction" settings
      ("forward direction" tile can be found using the search or in
the geometry
   3. Now get the fish to swim to the left or right.
      1. What happens when it reaches the wall?
      2. Can you fix it so it doesn't swim out of the tank?
         1. Hint: Look in the excellent quick guides (that big "?" in the
         upper left will open them for you)  and click on "Script
Tiles" and then
         "bounce motion"
      4. When the fish bounces does it look like you expected or what you
      1. Can you describe how the fish graphic "transformed" (in Spanish,
      transformado, in German verwandelt, in Greek μετατρέπονται, In
      Japanese: 変換,
      in kid speak: "it looks different".  Don't get hung up on the names
      (especially the ones mathemeticians use ;)  just figure out what they
      mean, that's the important thing. You only need to know the names to pass
      the test in school. To past the tests in life knowing the
meanings and how
      to use them is MUCH more important.
      2. Try drawing a fish on a piece of paper and cutting it out. Then
      move it through the air in an imaginary fish tank you can see in
your mind
      (seeing things again? Good ;) How do you do to the fish when it
reaches the
      edge of the tank and turns around?  Make the fish move the way you would
      expect a real fish to move. Then make it move the way it just moved in
      Etoys. This is the problem with Etoys (and anything else you use
to make a
      model), it does what you tell it (or in this case its default
behavior) and
      not necessarily exactly what happens in the real world.
   5. Know have your fish swim left and right and down a little.
      1. What happens when it bounces off the bottom of your ocean?
      2. Can you do that with your paper fish? Can you describe how you had
      to make your paper fish move?
      3. Hey imagine you are a fish and make yourself or a friend move like
      that crazy Etoy's fish you just created.
   6. Okay, now how can we make our Etoys fish look more like a real fish?
      1. Well do what Uncle Bert suggested and get the halo for your fish,
      click on the menu icon, then on "set rotation style". Then try and find a
      rotation style that makes your Etoys fish swim more like a real fish.
      2. Once you do this, can you figure out how this will change how the
      turn tiles work? (Good luck, it is far from obvious and really hard to
      figure out, but I am confident with patience and perseverance
you can do it,
      or just about anything else you put your mind to).

Dank Onkel Bert!!!

On Tue, Aug 17, 2010 at 6:32 AM, Bert Freudenberg <bert at freudenbergs.de>wrote:

> You still make it sound like the new flip tiles and the old rotation-style
> tile were somehow equivalent. They are not.
> I agree, however, that having a tile to set the rotation style is not
> strictly necessary - because it it available as menu item. I am not sure why
> it was added in the first place. Perhaps because tiles are more discoverable
> than menu entries. I couldn't imagine using this tile in a script. But
> changing the rotation style in the viewer while an object is bouncing around
> the screen is enlightening (though the up-down style seems to be there just
> for completeness, have not found an application yet).
> Anyway, independent of the new flip tiles: Do we want to hide the
> rotation-style tile?
> - Bert -
> On 17.08.2010, at 04:10, Steve Thomas wrote:
> Okay read Bert's comment in Tracker and I now understand that the graphic
> is flipped without changing heading (which differs from the implementation
> using "rotation style" which by design changes heading to cause the flip).
> So given that we want to have the minimum set of tiles from which you can
> create things.  Why do we need both?
> I understand the need to keep the older rotation style methods so older
> projects don't break, but IMNSOBOWO we should hide the rotation style tile.
> Stephen
> On Mon, Aug 16, 2010 at 9:20 AM, Steve Thomas <sthomas1 at gosargon.com>wrote:
>> On Mon, Aug 16, 2010 at 8:52 AM, Bert Freudenberg <bert at freudenbergs.de>wrote:
>>> On 16.08.2010, at 04:01, Steve Thomas wrote:
>>> Tried the new flip and tumble works great (for sketches, would be nice if
>>> this worked for all costumes, polygons would be trivial ;)
>>> Now that we have flip and tumble, do we need rotation style?  To me its
>>> confusing to have both and flip and tumble are much simpler to learn and
>>> use.
>>> Yes we need it. How else would you make a painted object go upright on
>>> the screen?
>> I agree we need the ability the "flip left right" and "flip up down"
>> functionality and the new tiles (now called "flip" and "tumble")
>> provide that functionality.
>> When I asked do we need rotation style, I was referring to the scripting
>> tile in the graphic category of the viewer not removing the functionality
>> which is provided in the code and accesible via the new "flip" and "tumble"
>> tiles.
>>> It disables actual rotation and automatically flips the graphic depending
>>> on heading. Flip and tumble are just one-shot operations that change the
>>> graphics.
>> Yes I understand that as you increase heading the graphic reaches a
>> tipping point around 90 or 180 degrees. I just don't see why we need both
>> methods, although to ensure old projects work, I was suggesting simply
>> hiding the tile "rotation style".
>> Stephen
>>  I think we hide the "rotation style" tile when in Etoys Friendly mode.
>>> Did you mean to write "we should"?
>> Yes. Although "we" is probably a poor choice of words as I do no coding,
>> that is left to over burdened, yet much appreciated developers such as
>> yourself.
>> Stephen
>>>  - Bert -
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