[Squeakland] Weird Heading numbers

[Alan Kay]

Our choice, which indeed goes against several longer standing 
conventions (like 0=East, +=counterclockwise, or 0 = N to 360 
clockwise), was adopted because we were looking for something that 
would be close to how a 7 year old child thinks and had a symmetric 
use of positive, negative and 0 (the original Etoys was for a younger 
age group). This has worked very well and has many merits for all the 
ages of children we work with.

And, of course one can assign e.g. 245 to heading and the player will 
point as expected.

I think the preference you suggest would be a good idea. There is 
already one for all playfields (including the world desktop) as to 
whether (0,0) should be in the lower left corner or the center of the 
rectangle ([] origin at center). Both have their merits. Similarly, 
both negative degrees and staying positive around the circle have 
their merits. And we should probably (and likely will) put in a 
preference for the school math system, now that we are starting to 
work with older children who are somewhat thinking along those lines.

I think starting with other than 0 would be a bad idea (and would 
also violate the compass convention). Similarly, school math starts 
with 0 pointing East, not 360.

If you want to see the regular compass headings you can write a 
simple script that ticks once or twice a second that does the easy 
conversion into a variable, then you can use a watcher to see the 
value on the screen.

The debates we have are not about your issue but the more critical 
one of whether we should have gone with the "school math" conventions 
for more coherence later on. I still like starting with the compass 
with N pointing up and clockwise for +. But there is a good QWERTY 
argument for the school math conventions. (This gets more pernicious 
with older children who have to learn the school convention -- and 
when vectors are used -- should they be in school math or in compass?)

Cheers,

Alan


At 03:19 PM 5/25/2007, mstram wrote:

>While playing with the Etoys, I've noticed the "weird" heading numbers.
>
>By that I mean when the object's heading passes 180 degrees, instead of
>continuing on to 190 ... 270 .. 360, we get the negative numbers.
>
>Why was this convention adopted ?
>
>I think if kids ... and some us "older" kids are going to be using headings
>it would be more educational and instructive to use "real" headings.
>
>Maybe an option / preference could be setup on which heading numbering
>system to use.
>
>The only minor problem I can see is whether it should be "0" or "360" to
>begin with.
>
>Just for the fun of it, I'm digging in and seeing if I can construct my own
>subclass to use the "360" system.   I have an idea for an ATC simulation I'd
>like to do and "real" headings .. or at least converted for input and output
>would be a must.
>
>Mike
>--
>View this message in context: 
>http://www.nabble.com/Weird-Heading-numbers-tf3818581.html#a10811065
>Sent from the SqueakLand mailing list archive at Nabble.com.
>
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