%!
% PostScript prologue for sphere_object.tex
% Version 1.00, 2006/08/02
%
/MaillageSphere {
30 dict begin
0 increment 360 increment sub {%
    /theta exch def
departPhi increment 90 increment sub {%
    /phi exch def
% newpath
    /Xpoint Rsphere theta cos mul phi cos mul def
    /Ypoint Rsphere theta sin mul phi cos mul def
    /Zpoint Rsphere phi sin mul def
PointsApresTransformations
  3dto2d
     moveto
% Centre de la facette
    /Xpoint Rsphere theta increment 2 div add cos mul phi increment 2 div add cos mul def
    /Ypoint Rsphere theta increment 2 div add sin mul phi increment 2 div add cos mul def
    /Zpoint Rsphere phi increment 2 div add sin mul def
PointsApresTransformations
    /zCentreFacette ED
    /yCentreFacette ED
    /xCentreFacette ED
% normale ŕ la facette
    /nXfacette xCentreFacette CX sub def
    /nYfacette yCentreFacette CY sub def
    /nZfacette zCentreFacette CZ sub def
% rayon vers point de vue
    /RXvue XpointVue xCentreFacette sub def
    /RYvue YpointVue yCentreFacette sub def
    /RZvue ZpointVue zCentreFacette sub def
% test de visibilité
    /PSfacette RXvue nXfacette mul
    RYvue nYfacette mul add
    RZvue nZfacette mul add
    def
condition {
theta 1 theta increment add {%
    /theta1 exch def
    /Xpoint Rsphere theta1 cos mul phi cos mul def
    /Ypoint Rsphere theta1 sin mul phi cos mul def
    /Zpoint Rsphere phi sin mul def
PointsApresTransformations
    3dto2d
    lineto
    } for
phi 1 phi increment add {
    /phi1 exch def
    /Xpoint Rsphere theta increment add cos mul phi1 cos mul def
    /Ypoint Rsphere theta increment add sin mul phi1 cos mul def
    /Zpoint Rsphere phi1 sin mul def
PointsApresTransformations
    3dto2d
    lineto
    } for
theta increment add -1 theta {%
    /theta1 exch def
    /Xpoint Rsphere theta1 cos mul phi increment add cos mul def
    /Ypoint Rsphere theta1 sin mul phi increment add cos mul def
    /Zpoint Rsphere phi increment add sin mul def
PointsApresTransformations
    3dto2d
    lineto
    } for
phi increment add -1 phi {
    /phi1 exch def
    /Xpoint Rsphere theta cos mul phi1 cos mul def
    /Ypoint Rsphere theta sin mul phi1 cos mul def
    /Zpoint Rsphere phi1 sin mul def
PointsApresTransformations
    3dto2d
    lineto
        } for
} if
} for
} for
end
} def