TikZ一例
一下午就画这么个东西：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | \begin{tikzpicture} \def\L{8} \coordinate (m) at (0.5*\L,0); \draw (m) node[below] {$m$}; \draw[->] (0,0) -- (1.2*\L,0); \node [circle,draw] (i) at (0,0) [minimum size=3cm] {}; \draw (i) node[below left] {$i$}; \node [circle,draw] (j) at (\L,0) [minimum size=3cm] {}; \draw (j) node[below right] {$j$}; \coordinate (a) at (tangent cs:node=i,point={(m)},solution=1); \coordinate (c) at (tangent cs:node=i,point={(m)},solution=2); \coordinate (b) at (tangent cs:node=j,point={(m)},solution=1); \coordinate (d) at (tangent cs:node=j,point={(m)},solution=2); \draw (a) node[above] {$A$} -- (i.center)-- (c) node[below] {$C$} -- (d) node[above] {$D$} -- (j.center)-- (b) node[below] {$B$} -- cycle; \draw[dashed] (0,0) -- (0,0.5*\L); \draw[dashed] (\L,0) -- (\L,0.5*\L); \node (l) at (0.5*\L,0.45*\L) {$l_{ij}$}; \draw[< -] (0,0.45*\L) -- (l); \draw[->] (l) -- (\L,0.45*\L); \draw (m) +(0:8mm) arc (0:22:8mm); \path (m) +(8:1.2cm) node{$\alpha_{ij}$}; \draw[dashed] (m) +($(0,0)-(a)$) -- (0,0); \draw[->] (0,0) +(0:18mm) arc (0:-22:18mm); \path (0,0) +(-8:22mm) node{$\alpha_{ij}$}; \draw[->] (0,0) -- (3,-2) node[below right] {$\overrightarrow{v}_{ij}$}; \draw[->] (0,0) +(0:8mm) arc (0:-32:8mm); \path (0,0) +(-18:12mm) node{$\beta_{ij}$}; \draw[dashed] (m) +($(0,0)-(c)$) -- (0,0); \end{tikzpicture} |
