[Etoys] The behavior of set heading is changed subtly

Yoshiki Ohshima yoshiki at vpri.org
Sat Dec 15 04:09:51 EST 2007


  Lately, we are fixing various bugs reported on trac and elsewhere,
and one of these items is:


(Try the example project made by Abe-san.)

  The simplest fix was to remove some logic that ignores the attempt
to set a new heading value if it is "close to" the old value.  The
logic was from old days and we (collectively) cannot really see the
reasoning behind it.

  We can take the check out (and the change is pushed to the update
stream already), but there is a small risk.

  The risk is that some existing projects may change their behavior; if
your program depends on the old behavior, where if you set a value to
heading but it actually doesn't change it sometimes, it could be a

  Also, the calculation of heading after an object bounced at the edge
is changed.  This is similar but more risky because in the old
behavior the heading was rounded.  If your project uses equality on
the heading value and bounce, this could be a problem.  (Now, we have
the function tile to "round" the value, so one could create a proper
script with it.)

  Please let us know if this change causes a trouble.  Thank you!

-- Yoshiki

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