I was thinking of using 'forward' together with griding so 'forward' would mean move one grid space, not one pixel.
I have been thinking of the unit pixel in Squeak and how it is not really explained anywhere I know of.
http://tracker.squeakland.org/browse/SQ-682

Karl

On Mon, May 23, 2011 at 5:25 AM, Steve Thomas <sthomas1@gosargon.com> wrote:
Ricardo,

Love it!  I especially like the idea of scaling (I think Karl had an idea like this a while back as well).  
Interesting how setting x to 0 has 0 = 2.220446049250313e-16 (close enough +/- epsilon?)

Stephen

On Sun, May 22, 2011 at 3:49 PM, Ricardo Moran <richi.moran@gmail.com> wrote:
Hi guys, following Bert's request I've resumed some of my work for GSoC hoping that it could be included in the next Etoys release :)

This is a new version (a complete rewrite, actually) of the graphing tools. This time I've followed Steve's idea of a simple number line object and the ability to change the scale of the playfield so that kids could make their own graphs (you can find the original conversation in this old thread).

You can see in the attached project that the playfield includes two new objects (horizontal number line and vertical number line). This objects have an extra category called "number line" with a few properties such as:
* increment
* min/max value
* scale
You can change the scale to define how much pixels will mean a unit of the number line. The increment will define the distance between labels. 

You will also find a new category on Playfield named "coordinate system". This category has:
* origin at center?
* origin
* scale x
* scale y
Using this properties you can define a different coordinate system for the objects you throw inside the playfield.

In the attached example I defined a playfield with the origin at 50@50 (this means 50 pixels from the bottom and left sides), an x scale of 1, and an y scale of 30. You can see how the position of the star changes acording to this scale while you move it inside the playfield and how it returns to its original scale when you pick it up and drop it outside the playfield.

For now it's just a proof of concept. A lot of things still don't use this new scaling (i.e. #forward:). But I want to know what you think about this direction.

Also, how much time do we have until the deadline? I have two exams tomorrow so I'm probably off for today. We can discuss this stuff at SqueakFest :)

See some of you in Montevideo!
Cheers,
Richo


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