Fichier spirale.jps — Modifié le 15 Février 2008 à 20 h 34
%% d'apres les donnees de
%% http://www.mathcurve.com/courbes3d/spiraleconic/pappus.shtml
-1 1 setxrange
-1 1 setyrange
200 setxunit
30.01 30 30 SetCamPos
0 0 0 SetCamView
/ScreenDist .3 def
-10 10 setxrange3d
-3 3 setyrange3d
2 setlinejoin
/a 1 def
/b pi 2 div def
/g {
3 dict begin
settvar
#rpn# a*Sin(b*t)*Cos(t)
#rpn# a*Sin(b*t)*Sin(t)
#rpn# a*Cos(b*t)
end
} def
/g' {
3 dict begin
settvar
#rpn# a*b*Cos(b*t)*Cos(t) - a*Sin(b*t)*Sin(t)
#rpn# a*b*Cos(b*t)*Sin(t) + a*Sin(b*t)*Cos(t)
#rpn# -a*b*Sin(b*t)
end
} def
/g'' {
3 dict begin
settvar
#rpn# -a*b^2*Sin(b*t)*Cos(t) - a*b*Cos(b*t)*Sin(t) - a*b*Cos(b*t)*Sin(t) - a*Sin(b*t)*Cos(t)
#rpn# -a*b^2*Sin(b*t)*Sin(t) + a*b*Cos(b*t)*Cos(t) + a*b*Cos(b*t)*Cos(t) - a*Sin(b*t)*Sin(t)
#rpn# -a*b*Sin(b*t)
end
} def
%rouge
0 pi 7 mul {g} CourbeR3
%stop
.1 setlinewidth
/aretescachees false def
GetCamPos setlightsrc
%solidgridOff
0 7 pi mul (g) .05 [305 6] newtube
%dup (rouge) outputcolors
dup [.1 .3] solidputhuecolors
%dup videsolid
drawsolid**