| Re: Delayed plotting in object graphics [message #22877 is a reply to message #22876] |
Wed, 13 December 2000 18:24   |
Ben Tupper
Messages: 186
Registered: August 1999
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Senior Member |
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Mark Hadfield wrote:
> "Ben Tupper" <pemaquidriver@tidewater.net> wrote in message
> news:3A36BBD9.1A4F589C@tidewater.net...
>> Hello,
>>
>> I am converting some 2d direct graphics to object graphics.
>> Past users of the program producing the graphics have wanted
>> to plot the points in 'slow motion'. That was easy to brute
>> force a lag using PLOTS and WAIT in a loop. Is there a way
>> of doing this with object graphics?
>
> Hmmm. Interesting. Some ideas:
>
> 1. Naive and ugly: Add the points to the scene one at a time; each time a
> point is added, redraw the scene and then wait. But once the scene has been
> constructed, every redraw will be instantaneous (well, as instantaneous as
> OG ever is).
>
> 2. Sophisticated and ugly: Add the points to the scene all at once, but with
> each point in a separate model. Make these models instances of a
> purpose-built subclass of IDLgrModel, say SlowModel. In SlowModel's class
> structure add a tag called delay, to be set to a sensible value in the Init
> method. Define SlowModel draw as:
>
> pro SlowModel::Draw, oSrcDest, oView
> self->ILgrModel::Draw, oSrcDest, oView
> wait, self.delay
> end
>
> Then every redraw will be slowed down. (But you might be surprised how often
> OG scenes get redrawn, especially when printing them!)
>
> 3. Best I can think of: Achieve a similar effect by manipulating colour. Put
> all the points in the same atom (much more efficient!) and set the atom's
> COLOR property so that one point is in a conspicuous colour (red, black) and
> the others in a less conspicuous one (grey). Each time you want to highlight
> a different point, get, rotate and reset the COLOR property vector. Calling
> WAIT in a loop is a pretty ugly way of driving a process like this--with a
> bit of extra effort you can get a better result using widget timer events.
>
> In general I find animation of one sort or another a very effective tool for
> helping visualise data. I have been experimenting with different ways of
> animating direct & object graphics (mainly the latter). You might want to
> look at some of my attempts at
> http://katipo.niwa.cri.nz/~hadfield/gust/software/idl/. In particular the
> MGHgrAnimatorBase class implements basic animator functionality with user
> controls and the MGHgrAnimator class is a general-purpose object graphics
> animator application. But I never thought of trying the sort of animation
> you describe and I don't have anything that would implement it directly.
>
Thanks Mark,
I think I shall try idea #3, making the points that are 'yet-to-be-plotted' the
background color while the 'already-plotted' points
a color distinct from the background. I suppose I could link the rate of the
plot to a slide widget, which, sliding from left to right, indicates the
relative position in the sequence of points. Then the user could move back and
forth through the sequence at will (maybe.)
I will also peek at your source page.
Ben
--
Ben Tupper
248 Lower Round Pond Road
POB 106
Bristol, ME 04539
Tel: (207) 563-1048
Email: PemaquidRiver@tidewater.net
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