[Newbies] Green Screen in Etoys

[Bert Freudenberg]

On 2012-06-11, at 05:57, Steve Thomas wrote:

> Folks,
> 
> 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 and the introduction video to wet the kids appetitie.


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 -


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