[PD] Array indexing for the wind and the birds

[Mathieu Bouchard]

On Tue, 23 Oct 2007, Roman Haefeli wrote:

> the main problem with dynamic patching is, that it is very likely, that 
> it causes audio drop-outs.

It wouldn't take much code to introduce something that can wrap dynamic 
patching in a way that prevents any DSP recompilation at the wrong moment.

E.g. If I have a patch that has 40 DSP objects, and then I instantiate an 
abstraction that has 10 dsp objects, 20 times, this recompiles DSP 20 
times, taking a total of 10*(40+(10+10*20)/2) = 1450 dsp_add calls. If the 
dynamic creations dominate, the time increases quadratically, which is one 
kind of "gets bad quite quickly".

Bracketing a bunch of dynamic object creations with a dsp-disable / 
dsp-enable pair, you just recompile once at the end, in the above example 
totalling to 40+10*20 = 240 dsp_add calls, which is exactly the size of 
the dsp graph you have at the end.

Getting any better than linear time is somewhat harder, especially for pd, 
but linear is already much better than quadratic.

> especially when creating ~-objects, the dsp graph needs to be 
> recompiled, which requires some cpu power.

... uninterruptible cpu power.

but if patches don't expect the dsp to be updated immediately, the job 
could be spread over several logical time blocks.

Of course the first solution I mentioned is best applied first, and then 
only bother with the latter if you need more realtimeness.

> pd-objects don't have a unique identifier, but they are just counted by 
> their creation order. when a certain objects is removed, all 
> subsequently created objects change their address.

It's not hard to add a method to the canvas class that will delete 
whichever range of indices of objects that you want from a patch.

  _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801, Montréal QC Canada