[PD] GUI and DSP
Hans-Christoph Steiner
hans at at.or.at
Sat Feb 11 04:48:17 CET 2012
On Feb 8, 2012, at 6:03 PM, Jonathan Wilkes wrote:
> ----- Original Message -----
>
>> From: Ivica Ico Bukvic <ico at vt.edu>
>> To: Mathieu Bouchard <matju at artengine.ca>; Jonathan Wilkes <jancsika at yahoo.com>
>> Cc: "pd-list at iem.at List" <pd-list at iem.at>
>> Sent: Wednesday, February 8, 2012 3:33 PM
>> Subject: Re: [PD] GUI and DSP
>>
>>
>>
>> Mathieu Bouchard <matju at artengine.ca> wrote:
>>
>>> Le 2012-02-08 à 11:55:00, Jonathan Wilkes a écrit :
>>>
>>>> While technically correct that's misleading because there's a
>> lot of
>>>> stuff happening on the 'pd' side that a reasonable person would
>>> assume
>>>> to be handled on the 'pd-gui' side. Well, more than that--
>> there's
>>>> stuff happening on the 'pd' side that doesn't need to
>> happen at all,
>>> but
>>>> it can use massive amounts of CPU and consequently a reasonable
>>> person
>>>> gets dropouts when moving an array that has only 100 points visible
>>> and
>>>> erroneously thinks, "Wow, I get dropouts just moving some polygons
>>
>>>> around on the screen? Tk stinks!"
>>
>> Or you could simply use pd-l2ork and a move arrays and other complex graphical
>> user interface objects using tags and never worry about that problem again.
>
> But even in pd l2ork, if you have a million element array with 100 elements showing,
> every time you click-drag a point in the array 'pd' recalculates the relationship between
> points/elements for the _entire_ array, right? At least that's what the code in g_array.c
> looked like it was doing when I last looked at it.
>
> If I understand it correctly, the 'pd-gui' waits for that c code to loop through the entire array before
> it updates-- thus if you swoop the mouse through the entire array it may look like a
> sluggish redrawing on Tk's part when actually it's redrawing just fine once it gets the
> new coords, which takes time (and can cause dropouts).
>
> That's a purposely exaggerated example, as it doesn't make a lot of sense to draw a
> 100-point garray that represents a 1000000-element array. But it makes me wonder
> whether the "strobing" effect you get with a ds-array that has a lot of elements
> happens because of similar heavy processing on the c side of things.
>
> Has anyone tried to make a big polygon with lots of moving parts purely in tcl/tk and
> measured the cpu? Might help to see Tk's limits separated out from pd.
I just made a pure Tcl array like thing. I made two versions, one using the create/delete technique that Pd uses, and another that uses the "coords" canvas command to update an existing line. They both seem to use about 45% of my CPU on Mac OS X 10.6.8 running Tcl/Tk/Carbon 8.5.10. Using Tcl/Tk/Cocoa 8.5.8 uses about the same, maybe a little less. Since the Tcl/Tk canvas is on the main CPU, and not the GPU, its not going to be particularly fast at such things.
.hc
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