Re: [PyOpenGL-Users] Collision Detections

[Richard J. <ric...@op...>]

On Friday 02 January 2004 12:43, Yannick Gingras wrote:
> On January 1, 2004 20:00, Richard Jones wrote:
> > Note that any implementation using map() will incur a function call
> > overhead, which is slow if you're not using a builtin function. Use a f=
or
> > loop instead
>
> Strange, I thought that the map() version was alway the more efficient
> as long as the lambda form was not invloved...
>
> Sure I can kick most of my map()s to rewrite in-line.  I like to
> substract vectors like that:
>
>   v1 =3D (0.0, 0.0,-0.5)
>   v2 =3D (1.0, 0.0, 0.5)
>   v3 =3D map(sub, v1, v2)

Well, the performance of that approach depends a lot on what "sub" is. If i=
t's=20
a function defined by you in Python, it's going to be as slow as a lambda=20
call. If it's a Python builtin function (say, operator.sub) then it'll be=20
very fast.

Note that you may want to look into Numeric Python to perform array=20
operations, as they're generally much faster than even using operator.sub (=
as=20
the former is highly optimised, whereas the latter is as general as it can=
=20
be).


> Thanks for the pointers.  I never tried to subdivide my world into
> sectors, I guess it's time.

Subdividing and bounds-checking are definitely worth the effort before you =
get=20
into code optimisation like we're talking about above :)


    Richard