1 \section{Positioning a named point
}
6 This is a command similar to
\verb+
\pnode(! x y)
{name
}+. It places
7 the node
\texttt{(name)
} at the point with the coordinates $(x,y,z)$,
8 viewed with the chosen point of view
\texttt{\Lkeyword{viewpoint
}=vx vy vz
}. We can
9 now use the point to mark it, draw lines, polygons, etc.
11 Let's place the centres of the atoms of the methanol molecule $
\mathrm{CH_3COH
}$.
13 \begin{LTXexample
}[width=
8cm
]
14 \begin{pspicture
}(-
4,-
4)(
4,
5)
15 \psset{viewpoint=
100 50 20 rtp2xyz,Decran=
20}
16 \axesIIID(
3,
3,
3)(
20,
20,
20)
17 \psPoint(-
4.79,
2.06,
0)
{C1
}
18 \psPoint(-
4.79,
15.76,
0)
{Ox
}
19 \psPoint(
8.43,
5.57,
0)
{C2
}
20 \psPoint(-
14.14,
3.34,
0)
{H3
}
21 \psPoint(
14.14,-
2.94,
8.90)
{H6
}
22 \psPoint(
14.14,-
2.94,-
8.90)
{H7
}
23 \psPoint(
6.43,-
16.29,
0)
{H8
}
24 \psline(C1)(H3)
\psline(C2)(H7)
25 \psline(C2)(H8)
\psline(C1)(C2)
26 \psline[doubleline=true
](C1)(Ox)
28 \uput[r
](H3)
{$
\mathrm{H_1
}$
}
29 \uput[l
](H6)
{$
\mathrm{H_2
}$
}
30 \uput[l
](H7)
{$
\mathrm{H_3
}$
}
31 \uput[l
](H8)
{$
\mathrm{H_4
}$
}
32 \uput{0.25}[u
](C1)
{$
\mathrm{C_1
}$
}
33 \uput{0.25}[d
](C2)
{$
\mathrm{C_2
}$
}
34 \uput{0.25}[r
](Ox)
{$
\red\mathrm{O
}$
}
35 \psdots[dotstyle=o,dotsize=
0.3](H3)(H6)(H7)(H8)
36 \psdots[dotsize=
0.4](C1)(C2)
37 \psdot[linecolor=red,dotsize=
0.4](Ox)