Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!.POSTED!not-for-mail From: Roedy Green Newsgroups: comp.lang.java.programmer Subject: Re: particle container in Java Date: Fri, 04 Nov 2011 15:54:39 -0700 Organization: Canadian Mind Products Lines: 36 Message-ID: <89r8b7964oa0l75o7cvgh06r53l3f4t96d@4ax.com> References: <17fed3e9-15e0-466c-bb24-10e74633ea1b@t8g2000yql.googlegroups.com> Reply-To: Roedy Green NNTP-Posting-Host: Z2l1DcCELS0rATq8NqV4Sw.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org X-Notice: Filtered by postfilter v. 0.8.2 X-Newsreader: Forte Agent 6.00/32.1186 Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:9537 On Thu, 03 Nov 2011 13:51:38 -0700, BGB 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.