On Tue, May 5, 2009 at 11:04 PM, Taco Hoekwater <t...@elvenkind.com> wrote: > Zhichu Chen wrote: >> >> What I want exactly is how to determine if there's anything on >> some region of the picture. I need this to test if the random >> point I picked is useful. > > That is easy to answer: you can't (well, not unless you invest a *lot* > of effort into creating a bitmap edge structure). Well, quick and pain. > > However what you can do is ask metapost to calculate intersectionpoints > with (the most likely ones of) the already existing objects. This may > be the easiest solution (even though it will be so slow that for large > numbers of items you may be forced to start a division tree). > > The core trick is that you randomly place a circle with random radius > inside an x-y field, and you keep those paths/pictures in an array. For > each newlyt generated circle, you look for an intersection with all the > already existing ones (and the rectangle borders) and keep trying > to re-place it until there are no more collisions.
Seems that I don't have too many choices. Maybe using lua to do the math and throwing the result to metapost is faster? I think I can do this, but I don't know how. The documents are a little limited. > > I can't come up with a solution that is both elegant and fast at the > moment, sorry. > > Best wishes, > Taco > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to > the Wiki! > > maillist : ntg-context@ntg.nl / > http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://tex.aanhet.net > archive : https://foundry.supelec.fr/projects/contextrev/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ > -- Best Regards Chen ---------------------------------------------------------------- Zhi-chu Chen | Shanghai Synchrotron Radiation Facility No. 2019 | Jialuo Rd. | Jiading | Shanghai | P.R. China tel: 086 21 5955 3405 | zhichu.chen.googlepages.com | www.sinap.ac.cn ---------------------------------------------------------------- ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : https://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________
