[Newbies] Green Screen in Etoys
sthomas1 at gosargon.com
Mon Jun 11 12:43:09 UTC 2012
On Mon, Jun 11, 2012 at 6:02 AM, Bert Freudenberg <bert at freudenbergs.de>wrote:
> On 2012-06-11, at 05:57, Steve Thomas wrote:
> I created a video of a code walk through for my students. It's an
> algorithm to create a "Green Screen" effect in Etoys.
> As I am definitely a novice when it comes to Squeak, I would appreciate
> any feedback on how I can correct/improve the explanations.
> Here is a link to the video of the code walk through<http://www.youtube.com/watch?v=T5WTS9ql_gQ> and
> the introduction video <http://youtu.be/B39DU7LRgL4>to wet the kids
> Awesome walkthrough!
> Nit picks:
> * pages 8 and 10: when you explain iterating over y, the example code on
> the right should use height, not width ;)
> * page 14: 0 at 0 in Squeak generally denotes the top-left, with increasing
> y values going down. Only Etoys pretends to use a proper Cartesian
> coordinate system with y going up, and the origin in the lower left (or
> center, depending on your playfield's settings). So the image code actually
> goes through the pixels from top to bottom, whereas you show it going from
> bottom to top.
> Also, for others to replicate your coding, you may have to briefly show
> how to make a textual Etoys script.
> - Bert -
> Beginners mailing list
> Beginners at lists.squeakfoundation.org
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