On May 26, 2007, at 0:19 , 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 don't know the original motivation. I'm sure there was a lot of discussion about introducing negative numbers that early. But it's quite simple actually - rotate one direction 5 degrees and you get "5", rotate the other way and you get "-5". Relatively simple to grasp.
And, for example, it makes using objects as rotational controls simpler. Unrotated the heading is 0, rotate a bit clockwise it's positive, rotate a bit counter-clockwise it's negative. This can then directly to increment the heading of another, moving object.
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.
You can use headingTheta from the geometry category.
- Bert -