pst-solides3d and hidden lines

Question

I am trying to draw figures with pstricks for the first time. Unfortunately, I am struggling with it. I was trying to draw a pentagon-cone and an octahedron using pst-solides3d, but it draws some lines dashed which actually are not hidden. I used this code:

\begin{pspicture}(-2,-1)(3,4) 
\psset{viewpoint=25 8 5,Decran=50} 
\psSolid[object=new, 
action=draw, 
sommets= 
0 0 0
0.343561 1.05737 1
-0.899454 0.653491 1
-0.899454 -0.653491 1
0.343561 -1.05737 1
1.11179 0 1, 
faces={  
[0 1 2]
[0 2 3]
[0 3 4]
[0 4 5]
[0 5 1]
[ 1 2 3 4 5]}]% 
\end{pspicture}

\begin{pspicture}(-2,-1)(3,4) 
\psset{viewpoint=25 8 5,Decran=100}
\psSolid[object=new, 
action=draw, 
sommets= 
%n=4
0 0 0 %0
0.420448 0.420448 0.5 %e1
-0.420448 0.420448 0.5 %e2
-0.420448 -0.420448 0.5 %e3
0.420448 -0.420448 0.5 %e4
0 0 1, %u 
faces={
[0 1 4]
[0 1 2]
[0 2 3]
[0 3 4]
[2 3 5]
[3 4 5]
[1 2 5]
[1 4 5]}]% 
\end{pspicture} 

The result, however, looks like this:

Obiously, lines which should be dashed (because they are hidden) are not and some lines which should be continuous are dashed. Does anyone know how to fix this problem?

---

Thanks for your answers. There is still something strange. If I set num=all, like in the code

\begin{pspicture}(-2,-1)(3,4) 
\psset{viewpoint=25 12 5,Decran=100}
%\axesIIID[showOrigin=false](1,1,1)(3,2,2.5)
\psSolid[object=new, 
action=draw*,
fillcolor=red,
opacity=.6,
fcol=8 (Blue),
num=all,
sommets= 
%n=4
0 0 0 %0
0.420448 0.420448 0.5 %e1
-0.420448 0.420448 0.5 %e2
-0.420448 -0.420448 0.5 %e3
0.420448 -0.420448 0.5 %e4
0 0 1 %u
0 1.18921 1 %w1
-1.18921 0 1 %w2
0 -1.18921 1 %w3
1.18921 0 1, %w4
faces={
[0 1 4]
[0 2 1]
[0 3 2]
[0 4 3]
[2 3 5]
[3 4 5]
[1 2 5]
[1 5 4]
[6 7 8 9]}]% 
\end{pspicture}

then I get the following result: which is obviously not as intended. How can I fix this?

Answer 1

The action key of pst-solides3d defines how the object is drawn:

• none: nothing is drawn.
• draw: draws the solid as a framework and sets up dashed lines for the hidden edges.
• draw*: draws the solid with dashed lines for the hidden edges and colours the visible faces.
• draw**: draws the solid with a painting algorithm, without the hidden edges and with colouration of the visible faces.

Using action=draw**, your document produces the following visibly incomplete polyhedra:

Although the edges of the faces make for a complete visual drawing, there are some missing faces. Now, you may notice that they formed part of your code, but they need to conform to the face specification (from the pst-solides3d documentation):

...a face is characterized by a list of the indices of it's vertices, listed in counter-clockwise order when the face is viewed from the exterior of the solid.

The easiest way to find out the order (and which direction is clockwise or counter-clockwise) is to add the key-value num=all and show=all to your \psSolid object. That is, use

\psSolid[action=draw,num=all,show=all,...]

This numbers all the vertices (sommets) and all the faces (faces). Rewriting the faces in the correct counter-clockwise fashion produce the expected results:

\documentclass{article}
\usepackage{pst-solides3d}% http://ctan.org/pkg/pst-solides3d
\begin{document}
\begin{pspicture}(-2,-1)(3,4) 
\psset{viewpoint=25 8 5,Decran=50} 
\psSolid[object=new,%num=all,show=all,
  action=draw,
  sommets= 
    0 0 0
    0.343561 1.05737 1
    -0.899454 0.653491 1
    -0.899454 -0.653491 1
    0.343561 -1.05737 1
    1.11179 0 1, 
  faces={%
    [0 1 5]
    [0 5 4]
    [0 4 3]
    [0 3 2]
    [0 2 1]
    [1 2 3 4 5]}]% 
\end{pspicture}

\begin{pspicture}(-2,-1)(3,4) 
\psset{viewpoint=25 8 5,Decran=100}
\psSolid[object=new, 
  action=draw,%num=all,show=all,
  sommets= 
    0 0 0 %0
    0.420448 0.420448 0.5 %e1
    -0.420448 0.420448 0.5 %e2
    -0.420448 -0.420448 0.5 %e3
    0.420448 -0.420448 0.5 %e4
    0 0 1, %u 
  faces={
    [0 2 1]
    [0 1 4]
    [0 4 3]
    [0 3 2]
    [5 1 2]
    [5 2 3]
    [5 3 4]
    [5 4 1]}]% 
\end{pspicture}

Answer 2

Using the object octahedron:

\documentclass{article}
\usepackage[dvipsnames]{pstricks}
\usepackage{pst-solides3d}
\begin{document}
\psset{viewpoint=25 8 5,Decran=50} 
\begin{pspicture}(-2,-2)(3,3) 
\psSolid[object=octahedron, a=1, hue=0.2 0.6]
\end{pspicture}
%
\begin{pspicture}[solidmemory](-2,-2)(2,2) 
\psSolid[object=octahedron, a=1,
   plansepare={[0 0 1 0]},% plain to cut the object: z=0
   name=Octa, action=none]
\psSolid[object=load, load=Octa1, hue=0.2 0.6]% lower half
\psSolid[object=load, load=Octa0, hue=0.2 0.6](0,0,0.5)% upper half
\end{pspicture}

\end{document}