Help with morph and world refresh
ned at bike-nomad.com
Sat Apr 5 17:10:10 UTC 2003
On Saturday 05 April 2003 08:27 am, Stephane Ducasse wrote:
> In fact the problem with not pick the diamonds only occurs if I
> execute from a workspace really fast multiple times the expression
> b2 go.
> b2 canPick ifTrue: [b2 pick]
> This suggests to me that I'm executing several commands at the same
If these are done as part of the same World cycle, then you won't see
the display update until after the last one. You could do something
like forcing the changes to the screen in between, but there are
probably better ways to do it.
You could try adding this for testing, at least:
Display forceToScreen: myMorph bounds; forceDisplayUpdate
This will force any invalidated regions to be redrawn visibly.
> >> the bot misses to pick some diamonds: really annoying. I guess
> >> that this is because the method can pick and pick do not contain
> >> World doOneCycle.
Does it really miss doing something, or just not show that it is doing
> Nathanael already did that for the turtle with animation that I
> have. But this is really complex.
> I'm amazed to see how difficult it is to simply do a stupid small
> in Squeak that requires animation (ok I do not use step).
Animation when combined with a display that caches changes requires
some kind of synchronization.
> Still. I'm not sure that I can really develop your solution but
> suggesting it. When I read it, I'm really frustrated by my lack of
concurrent programming skills.
Concurrent programming isn't easy in general. One of the nice things
about the eToy system (though it certainly has a number of
limitations) is that it presents concurrent programming in a fashion
that is easy to get right (no explicit synchronization).
In Morphic, there's a simplifying assumption that everything is
happening in a single Process.
This is the reason that most of the time step is the best choice, if
you can use it. The display is forced to the screen at the end of
every world cycle.
> Would the WorldState>>addDeferredUIMessage: solve my problem?
Not necessarily, as these messages are processed at the beginning of
the World's update cycle. If there are multiple messages which each
will move your Morph you won't see the intermediate position.
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