Fichier essai_11.jps — Modifié le 20 Février 2008 à 14 h 58
%% d'apres les donnees de
%% http://www.mathcurve.com/courbes3d/spiraleconic/pappus.shtml
-1 1 setxrange
-1 1 setyrange
200 setxunit
0.01 0 30 SetCamPos
0 0 0 SetCamView
/ScreenDist .2 def
-10 10 setxrange3d
-3 3 setyrange3d
2 setlinejoin
/a 1.2 def
/b 3 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
%% 600 setresolution
%% %rouge
%% 0 pi 4 mul {g} CourbeR3
%% stop
.1 setlinewidth
/aretescachees false def
GetCamPos setlightsrc
%solidgridOff
0 4 pi mul (g) .05 [605 6] newtube
%dup (rouge) outputcolors
dup [.6 .7] solidputhuecolors
%dup videsolid
drawsolid**