3 \subsection{Direct definition}
5 The object \Lkeyword{polygone} allows us to define a \Index{polygon}. We use
6 the option \Lkeyword{args} to specify the list of vertices:
7 \texttt{[object=polygone,args=$A_0$ $A_1$ \ldots $A_n$]}
9 There are other ways to define a polygon in 2D. The options
10 \Lkeyword{definition} and \Lkeyword{args} support these methods:
14 %% syntaxe : pol u --> pol'
15 \item \texttt{\Lkeyword{definition}=\Lkeyword{translatepol}};
16 \texttt{\Lkeyword{args}=$pol$ $u$}.
18 Translation of the polygon $pol$ by the
21 %% syntaxe : pol u --> pol'
22 \item \texttt{\Lkeyword{definition}=\Lkeyword{rotatepol}};
23 \texttt{\Lkeyword{args}=$pol$ $I$ $\alpha $}.
25 Image of the polygon $pol$
26 after a rotation with centre $I$ and angle $\alpha $
28 %% syntaxe : pol I alpha --> pol'
29 \item \texttt{\Lkeyword{definition}=\Lkeyword{hompol}};
30 \texttt{\Lkeyword{args}=$pol$ $I$ $\alpha $}.
32 Image of the polygon $pol$
33 after a homothety (dilation) with centre $I$ and ratio $\alpha$.
35 %% syntaxe : pol I --> pol'
36 \item \texttt{\Lkeyword{definition}=\Lkeyword{sympol}};
37 \texttt{\Lkeyword{args}=$pol$ $I$}.
39 Image of the polygon $pol$ after a
40 reflection in the point $I$.
42 %% syntaxe : pol D --> pol'
43 \item \texttt{\Lkeyword{definition}=\Lkeyword{axesympol}};
44 \texttt{\Lkeyword{args}=$pol$ $d$}.
46 Image of the polygon $pol$ after a
47 reflection in the line $d$.
51 In the following example we define, name and draw the polygon with
52 vertices $(-1,0)$, $(-3, 1)$, $(0, 2)$, then---in blue---the
53 image after a rotation about the point $(-1,0)$ through an angle
54 $-45$. Finally, we translate the polygon with the vector shift
55 $(2,-2)$ by directly incorporating \textit{jps code} within the
56 argument of \Lkeyword{definition}.
58 \begin{LTXexample}[width=7.5cm]
59 \begin{pspicture}(-3,-3)(4,3.5)%
60 \psframe*[linecolor=blue!50](-3,-3)(4,3.5)
61 \psset{lightsrc=50 20 20,viewpoint=50 30 15,Decran=60}
63 \psSolid[object=grille,
65 linewidth=0.5\pslinewidth,linecolor=gray,]
66 %% definition du plan de projection
70 base=-3.2 3.2 -2.2 2.2,
81 \psProjection[object=polygone,
85 \psProjection[object=polygone,
90 %% du code jps dans la definition
91 \psProjection[object=polygone,
92 definition={2 -2 addv} papply,
93 fillstyle=hlines,hatchcolor=yellow,
98 \axesIIID(4,2,2)(5,4,3)