[pstricks] pst-3dplot

[camus.philippe at free.fr]

I tried to make some experiment with 3dplot, and I found a strange thing :
According to the doc, the kernel of the "3dto2d" transform matrice should be
   [\sin(\Alpha)*\cos(\Beta) ;\cos(\Alpha)*\cos(\Beta);\sin(\Beta) ]
So, when I test the following :
\pspicture(-5,-5)(5,5)
\psset{Alpha=150,Beta=40}
\pstThreeDCoor[xMin=0,xMax=4,yMin=0,yMax=4,zMin=0,zMax=4]
\def\al{60}\def\be{130} %just because I can't use \Alpha and \Beta !
\FPeval{a}{cos(\be)*sin(\al)}
\FPeval{b}{cos(\be)*cos(\al)}
\FPeval{c}{sin(\be)}

\pstThreeDLine(\a,\b,\c)(0,0,0)

\endpspicture

I expect that the 3DLine is reduced to a point (the origin).
But it's not the case and I'm wondering why !
Philippe