[PD] still struggling with basic understanding of Gem dataflow

[Hans-Christoph Steiner]

It would be great to have some of this documented better.  I mentioned  
in the book sprint email that there are lots of Gem examples, but  
there isn't really any text that I could find that introduces these  
concepts of Gem.

So if you do figure this stuff out, please join us for the book  
sprint, or point us to your findings so someone can write it up!

.hc

On Mar 25, 2009, at 1:17 PM, Ben Baker-Smith wrote:

> Hi John,
>
> You are correct.  Gem does not follow the normal top to bottom rules  
> of PD.  I believe its render chain has more to do with the rules of  
> OpenGL than with PD.
>
> Sorry I can't give you an easy way of figuring which objects will be  
> processed first.  If there is one then I've never heard/read it.   
> Keep experimenting.
>
> For more information on this, I recommend looking up the "a flawed  
> Gem" thread in the PD-List archives (and whatever thread that came  
> out of).
> It'll give you some more information about Gem's relation to OpenGL  
> and some users frustration with similar situations as yours.
>
> I love using Gem, it's the environment I primarily work in when  
> using PD.  However, it's a bit of a wild beast (at least to a non- 
> programmer like myself).
>
> Best of luck,
> -Ben
>
>
>
> >[Gemhead]
> >|
> >[object 1]
> >|
> >[object 2]
> >|
> >[object 3]
> >
> >we cannot conclude that the output of [object 1] feeds the input of  
> [object
> >2] and the output of [object 2] feeds the input of [object 3]. We  
> only know
> >that the data will be processed by objects 1, 2 and 3 but not in  
> what order
> >they will be processed.
> >
> >Further perhaps we cannot conclude that the output of an object is  
> actually
> >the result of the object having processed the data. Demonstrating  
> this: in
> >my patch example, [pix_buffer_write] outputs different data than it  
> stores,
> >or examples 1 and 3 would be the same.
> >
> >And this leads me to a more general statement of my original  
> question: how
> >can I determine the order in which objects are processed in Gem?
> >
> >And my specific example which started this thread: how would one  
> apply a
> >rotation to an image, then apply [pix_rtx] to the rotated image?
> >
> >-John
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