| Re: Widgets and Animation Loops in IDL 5.0 [message #16464 is a reply to message #16387] |
Mon, 26 July 1999 00:00   |
drphys
Messages: 4
Registered: July 1999
|
Junior Member |
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thank you!
I believe that this is what I need.
Shawn
In article <7ng6aq$s6q$1@clam.niwa.cri.nz>,
"Mark Hadfield" <m.hadfield@niwa.cri.nz> wrote:
> <drphys@my-deja.com> wrote in message
news:7na6kq$q9b$1@nnrp1.deja.com...
>> Hi,
>> I am using IDL 5.0 on a DEC Alpha. I am animating a 3D plot of a
>> particle trajectory by incrementing the "az" variable and then
>> replotting in a loop. I decided to add widgets to control the speed
of
>> rotation and the angle about the x axis "ax". I have found this to
be
>> unworkable so far because once the code enters the loop the widgets
do
>> not issue events, so my event handlers do not get called. This was
>> easily fixed by using widget_control commands inside the loop and
using
>> sliders to control the speed and x angle, however, I can not find a
>> method to exit the loop, except for possibly adding a slider that
could
>> turn it off.
>
> Do not use a for or while loop for an animation. Instead, set up your
code
> so that
> each time a frame is drawn, a widget timer event is set with
>
> WIDGET_CONTROL, TIMER=delay
>
> (where delay can be zero). Then the widget event handler catches the
timer
> event,
> draws the next frame, and resets the timer, etc. The loop can be
terminated
> by instructing
> the event handler to ignore timer events. This is how CW_ANIMATE does
it.
> Information about the current state of the animation (current frame,
which
> direction
> we're going in, where the end is & what to do when we get there) can
be
> stored in a
> structure stored attached to one of the widget's UVALUE fields or,
better,
> in an object.
>
> I have found object graphics particularly good for animations, and I
have
> written a
> set of animator classes, which illustrate the above technique.
>
> See my Web page:
http://katipo.niwa.cri.nz/~hadfield/gust/software/idl/.
> In particular the MGHgrAnimation and MGHgrAnimator classes and the
> MGH_EXAMPLE_ANIMATOR routine. But you'll need version 5.2 to run them.
>
> ---
> Mark Hadfield m.hadfield@niwa.cri.nz
> National Institute for Water and Atmospheric Research
> PO Box 14-901, Wellington, New Zealand
>
>
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