Re: [pygame] fast sqrt? and profiling

[René Dudfield <renesd@xxxxxxxxx>]

I forgot to mention this quadtree code too:
    http://www.pygame.org/wiki/QuadTree


cu,


On Wed, Jan 21, 2009 at 5:06 PM, René Dudfield <renesd@xxxxxxxxx> wrote:
> hi,
>
> you'll want to use a spacial hash.
>
> Like this quadtree for example:
>    http://www.pygame.org/project/752/
>
> cu!
>
> On Wed, Jan 21, 2009 at 4:27 PM, Jake b <ninmonkeys@xxxxxxxxx> wrote:
>> I'm writing a prototype, where I want a bunch of 'blobs', that clump/swarm,
>> yet seperate. ( they keep min distance from each other, they don't overlap (
>> or at least don't stay) )
>>
>> What I am doing, is every 250ms calculate each units neighbors. ( then,
>> every loop, move away from each cached neighbor. ) My FPS stays around 26-30
>> until I get 62+ units, then it drops like a stone. [ every Unit() waits 250
>> for its update, I calc just it, not all Units. ]
>>
>> From profiling ( and testing ) I know the function to calculate locals (
>> neighbors ) is causing most of the slowdown.
>>
>> 1) Is there a suggested fast sqrt module thats portable?
>>
>> 2) Is it bad to use isinstance in CPU intensive loops? ( ie: function
>> list_type() )
>>
>> 3) it looks like euclid.Vector2.__sub__ is taking a lot of time. Is this
>> abnormally high? or expected? Meaning should I be using a different lib for
>> speed? [ that particular function uses isinstance() ]
>>
>> 4) Do you have some useful profile queries you've found?
>>
>> 5) Should I be staggering the dist() calls among multiple game updates()? [
>> sort of am indirectly, but no enforcement. ] Or decouple physics from
>> graphics ?
>>
>> Heres the functions I mentioned above:
>>
>> def calc_local(self):
>>         """re-calc 'who are my neighbors' to cache for later."""
>>         l = [] #first, get list of neighbors
>>
>>         for u in self.game.units.list_type(Unit):
>>             if u == self: continue # don't collide self.
>>             if collide_circle( self.loc, u.loc, self.rad+self.local, u.rad):
>>                 l.append(u)
>>         self.local_cache = l
>>
>> def list_type(self, t):
>>         """get list of units by class type. example: .list_type(Unit)"""
>>
>>         l = []
>>         for u in self.units:
>>             if isinstance(u, t): l.append(u)
>>
>> Here's the profiling I'm basing this on:
>> profile output: ( query = "p.sort_stats('time').print_stats(10)" )
>>
>>   Ordered by: internal time
>>   List reduced from 311 to 10 due to restriction <10>
>>
>>   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
>>      388    2.652    0.007    2.652    0.007 {built-in method tick}
>>     1446    1.185    0.001    3.656    0.003 main.py:151(calc_local)
>>    98318    0.790    0.000    1.242    0.000
>> C:\Python25\lib\euclid.py:172(__sub__)
>>    80355    0.538    0.000    2.071    0.000
>> C:\jake_root\data\py\jake_includes\jakelib\util.py:49(dist)
>>      194    0.520    0.003    0.520    0.003 {pygame.display.flip}
>>    98583    0.497    0.000    0.681    0.000
>> C:\Python25\lib\euclid.py:243(__abs__)
>>    80355    0.391    0.000    2.462    0.000
>> C:\jake_root\data\py\jake_includes\jakelib\util.py:70(collide_circle)
>>   147359    0.348    0.000    0.348    0.000 {isinstance}
>>   147253    0.338    0.000    0.338    0.000
>> C:\Python25\lib\euclid.py:90(__init__)
>>    12175    0.288    0.000    0.694    0.000
>> C:\Python25\lib\warnings.py:24(warn)
>>
>>
>> I know its a lot of questions, that's why I numbered it to simplify replies.
>> Thanks for the help.
>> --
>> Jake
>>
>