No you cannot. If you really need unit vector you need to divide by square root. Question is, do you need unit vectors? (often you don't).
-Marten Amir Taaki wrote: > hey thanks and that's not the problem- to convert them to unit vectors > you have to divide the vector by it's length- that's the potential > square root I wish to avoid. > > I need to add more words to my posts instead of imagining I'm a telepath. > > On Sat, Jul 26, 2008 at 8:43 PM, res <[EMAIL PROTECTED]> wrote: > > On 26.07.2008 19:46, Amir Taaki wrote: > > Hi! > > Since this calculate potentially gets done very many times per > frame, I'd like to minimise the heaviness of it- what's fastest > way to tell if point C lies between A-B? > > c = C - A > > I'd do c^ = AB^ (when unit vectors) and if |c| < |AB| > > But is it possible to avoid the square root in converting them > to unit vectors, possibly by some other method? Thanks > > > Just skip it. When comparing distances it doesn't matter if you just > compare the sum of squares with or without rooting it. > > -f.r. > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's > challenge > Build the coolest Linux based applications with Moblin SDK & win > great prizes > Grand prize is a trip for two to an Open Source event anywhere in > the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > <http://moblin-contest.org/redirect.php?banner_id=100&url=/> > _______________________________________________ > Crystal-main mailing list > [email protected] > <mailto:[email protected]> > https://lists.sourceforge.net/lists/listinfo/crystal-main > Unsubscribe: mailto:[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]>?subject=unsubscribe > > > > ------------------------------------------------------------------------ > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > > > ------------------------------------------------------------------------ > > _______________________________________________ > Crystal-main mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/crystal-main > Unsubscribe: mailto:[EMAIL PROTECTED] ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Crystal-main mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/crystal-main Unsubscribe: mailto:[EMAIL PROTECTED]
