Added schematic illustration of viewing frustum

git-svn-id: http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free@8807 383ad7c9-94d9-4d36-a494-682f7c89f535

Doxygen/Developer/pics/src/projection.tex

+\documentclass{minimal}
+
+% Tikz
+\usepackage{pgf}
+\usepackage{tikz}
+
+\tikzset{
+ 	vertex/.style={draw=none,circle,fill=black,inner sep=2pt},
+	edge/.style={draw,black,thick},
+	thinedge/.style={draw,black,line width=.4pt},
+	dedge/.style={draw,black,line width=.4pt,dashed}
+}
+
+\begin{document}
+
+\begin{center}
+ \begin{tikzpicture}[x  = {(1cm,0.0cm)},
+                     y  = {(0.0cm,1.0cm)},
+                     z  = {(2.0cm,0.6cm)}]
+ 
+\coordinate (O) at (0,0,0);
+
+\coordinate (lo) at (-3,2,2);
+\coordinate (ro) at (3,2,2);
+\coordinate (lu) at (-3,-2,2);
+\coordinate (ru) at (3,-2,2);
+
+\coordinate (LO) at (-6,4,4);
+\coordinate (RO) at (6,4,4);
+\coordinate (LU) at (-6,-4,4);
+\coordinate (RU) at (6,-4,4);
+
+\coordinate (c) at (0, 0, 2);
+\coordinate (co) at (0, 2, 2);
+
+\draw[fill=gray,draw=none,opacity=0.5] (O) -- (c) -- (co);
+%\draw[fill=gray,opacity=0.5] (O) -- (17:1.2cm) arc (17:21.5:6cm);
+
+\draw[edge] (lo) to (ro) node[pos=.5,above=.1em] {$t$};
+\draw[edge] (lo) to (lu) node[pos=.5,left] {$l$};
+\draw[edge] (ro) to (ru) node[pos=.5,right=.1em] {$r$} node[pos=.15,right] {$\texttt{Near plane}$};
+\draw[edge] (lu) to (ru) node[pos=.5,above=.-1.2em] {$b$};
+
+\draw[edge] (LO) to (RO) node[pos=.5,above] {$\texttt{Far plane}$} {};
+\draw[edge] (LO) to (LU) {};
+\draw[edge] (RO) to (RU) {};
+\draw[edge] (LU) to (RU) {};
+
+\draw[thinedge] (O) to (RO) {};
+\draw[thinedge] (O) to (LO) {};
+\draw[thinedge] (O) to (RU) {};
+\draw[thinedge] (O) to (LU) {};
+
+\draw[dedge] (O) to node[pos=.33,above=.5em]{$\varphi$} (c) {};
+\draw[dedge] (O) to (co) {};
+
+\node[vertex] at (O) {};
+
+%\draw[->, thick] (-0.4,3) arc (0:320:20pt);
+
+\end{tikzpicture}
+\end{center}
+
+\end{document}