[Pharo-users] Calculate angle between two vectors (probably @Igor :)

Nicolai Hess nicolaihess at web.de
Wed Mar 19 06:08:03 EDT 2014

2014-03-19 8:49 GMT+01:00 MartinW <wm at fastmail.fm>:

> Nicolai Hess wrote
> > This was of course wrong, I don't know what the
> > other method computes, but not the angle between two vectors.
> Yes i also wrote a test and i think my method is right.
> Nicolai Hess wrote
> > Now the question is, why do you think your method is wrong / the boids
> > behave wrong?
> When i use my method to calculate the field of vision the Boids always fly
> from top left to down right and if i turn on the circling option, they
> crowd
> in the bottom right quadrant.
> If i give them a 360 degree field of vision by always returning true for
> isInFieldOfVision they behave correctly. This means they fly in a nice
> circle around the center and if circling is turned off, the swarm flies in
> different directions each time you start the simulation.
> Perhaps the problem is not the calculation of the angle but is in the
> isInFieldOfVision: method...

:) yes and I think the testcases in testIsInFieldOfVision
are wrong, or I misunderstand how the boids are moving.

in testIsInFieldOfVision
subject has velocity 100 at 0, I understand this as "moves from left to right".
testobject other2 and other3 are above and below subect, and not behind and
in front, both should be visible with the fieldOfView.
Btw. the field of view is rather big, 0.75*Float Pi is 135 degree, but
clock *and* counterclockwise
->  270 degree field of view.

And it is funny to change the field of view to 0, after the boids started.

> --
> View this message in context:
> http://forum.world.st/Calculate-angle-between-two-vectors-probably-Igor-tp4749351p4749697.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
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