[an error occurred while processing this directive] [an error occurred while processing this directive][an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] (none) [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive][an error occurred while processing this directive] [an error occurred while processing this directive][an error occurred while processing this directive] [an error occurred while processing this directive][an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive] (none) [an error occurred while processing this directive] [an error occurred while processing this directive] [an error occurred while processing this directive][an error occurred while processing this directive]
 
[an error occurred while processing this directive] [an error occurred while processing this directive]
Skåne Sjælland Linux User Group - http://www.sslug.dk Home   Subscribe   Mail Archive   Forum   Calendar   Search
MhonArc Date: [Date Prev] [Date Index] [Date Next]   Thread: [Date Prev] [Thread Index] [Date Next]   MhonArc
 

Re: [PROGRAMMERING] B-Spline



Mon, 27 Sep 2004 22:48:01 +0200, Peter Maersk-Moller <sslug@sslug> skrev:

Hej

Jeg leder efter et stykke kode, der lader mig udregne en
B-spline-kurve med tre punkter P0, P1 og P2, hvor

   P0 = 0,0
   P1 = x1,y1
   P2 = 255,255

   og 0 < x1 < 255
   og 0 < y1 < 255
   og x1 >= y1

Jeg har kigget lidt på http://www.ibiblio.org/e-notes/Splines/Bezier.htm
men kan ikke rigtig gennemskue, hvordan

P(t) = (1-t)P01 + tP11 = (1-t)[(1-t)P0 + tP1] + t[(1-t)P1 + tP2] = (1-t)2P0 + 2(1-t)tP1 + t2P2 ,

[BEMÆRK - i anden potens er ikke gengivet rigtig her. Se webside med Quadratic Bezier spline]

Jeg kan ikke rigtig oversætte ovenstående til en funktion a'la

f(x) = ........

da jeg ikke kan se, hvordan y1 (for P1) indgår, eller også misforstår jeg
funktionen.
Funktionen er ikke f(x) men f(t) hvor t er en step variabel (oftest tid og deraf navnet t).
Hvis du anskuer dit koordinatsystem som gulvet i et danselokale er punktmængden P(t) beskrivelsen af hvor i lokalet du har været siden du startede din dans (t=0).
Så derfor har du for to dimensioner to stedfunktioner x(t) og y(t) der tilsammen udgør stedfunktionen p(t) = p(x(t);y(t)).


Håber det hjælper på forståelsen :)
-Ellers må du råbe op ;)

--
Med venlig hilsen
/Zmit/
RLU # 314205


 
Home   Subscribe   Mail Archive   Index   Calendar   Search

 
 
Questions about the web-pages to <www_admin>. Last modified 2005-08-10, 22:44 CEST [an error occurred while processing this directive]
This page is maintained by [an error occurred while processing this directive]MHonArc [an error occurred while processing this directive] # [an error occurred while processing this directive] *