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Re: particle container in Java

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On Thu, 03 Nov 2011 13:51:38 -0700, BGB <cr88192@hotmail.com> wrote,
quoted or indirectly quoted someone who said :

>in my 3D engine (mostly written in plain C) I use a BSP-tree style 
>structure.

I had never heard of Binary Space Partitioning trees before.
 http://en.wikipedia.org/wiki/Binary_space_partitioning

I invented Hanging Moss myself back in the 1970s to optimise the
motions of pen-plotters.  The problem was to rapidly find a nearby
thing to draw next.  It was astoundingly faster that computing the
distance to everything else and finding the minimum.

It is just a classifying grid.  At each square you have a chain of
objects.  To find a point near another you chase the chain in the
appropriate square. If you don't find anything you search the next
outer ring of squares. 

If you doubly link the chain, you can efficiently delete and insert.
If you singly link, you can do LIFO/FIFO.

-- 
Roedy Green Canadian Mind Products
http://mindprod.com
Capitalism has spurred the competition that makes CPUs faster and 
faster each year, but the focus on money makes software manufacturers 
do some peculiar things like deliberately leaving bugs and deficiencies
in the software so they can soak the customers for upgrades later.
Whether software is easy to use, or never loses data, when the company
has a near monopoly, is almost irrelevant to profits, and therefore 
ignored. The manufacturer focuses on cheap gimicks like dancing paper 
clips to dazzle naive first-time buyers. The needs of existing 
experienced users are almost irrelevant. I see software rental as the 
best remedy.

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Thread

particle container in Java bob <bob@coolgroups.com> - 2011-11-03 01:05 -0700
  Re: particle container in Java Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-11-03 08:33 +0000
  Re: particle container in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-11-03 08:12 -0700
    Re: particle container in Java BGB <cr88192@hotmail.com> - 2011-11-03 13:51 -0700
      Re: particle container in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-11-04 15:54 -0700
        Re: particle container in Java BGB <cr88192@hotmail.com> - 2011-11-04 19:48 -0700
          Re: particle container in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-11-05 06:42 -0700
  Re: particle container in Java Giovanni Azua <bravegag@hotmail.com> - 2011-11-03 23:38 +0100
    Re: particle container in Java BGB <cr88192@hotmail.com> - 2011-11-03 22:41 -0700
      Re: particle container in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-11-05 06:49 -0700
        Re: particle container in Java BGB <cr88192@hotmail.com> - 2011-11-05 09:16 -0700
          Re: particle container in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-11-06 03:07 -0800
            Re: particle container in Java Giovanni Azua <bravegag@hotmail.com> - 2011-11-06 15:15 +0100
              Re: particle container in Java BGB <cr88192@hotmail.com> - 2011-11-06 11:06 -0700
  Re: particle container in Java Arne Vajhøj <arne@vajhoej.dk> - 2011-11-03 19:03 -0400

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