I am trying to create a tikz image based on the following screenshot:
I can figure out how to draw a pyramid, but I have so far been hopeless at drawing the red shaded regions. Here is the minimal progress I have made:
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
[x={(0.648577cm, -0.290453cm)},
y={(0.759883cm, 0.300370cm)},
z={(-0.043879cm, 0.908523cm)},
scale=2.000000,
back/.style={densely dotted, thin},
edge/.style={densely dotted, thin},
facet/.style={fill=blue!95!black,fill opacity=0.000000},
vertex/.style={inner sep=1pt,circle,draw=green!25!black,fill=green!75!black,thick,anchor=base}]
\coordinate (-0.75000, -0.75000, -0.75000) at (-0.75000, -0.75000, -0.75000);
\coordinate (0.75000, -0.75000, -0.75000) at (0.75000, -0.75000, -0.75000);
\coordinate (-0.75000, 0.75000, -0.75000) at (-0.75000, 0.75000, -0.75000);
\coordinate (0.75000, 0.75000, -0.75000) at (0.75000, 0.75000, -0.75000);
\coordinate (0.00000, 0.00000, 1.00000) at (0.00000, 0.00000, 1.00000);
\fill[facet] (0.00000, 0.00000, 1.00000) -- (-0.75000, -0.75000, -0.75000) -- (-0.75000, 0.75000, -0.75000) -- cycle {};
\fill[facet] (0.00000, 0.00000, 1.00000) -- (-0.75000, -0.75000, -0.75000) -- (0.75000, -0.75000, -0.75000) -- cycle {};
\fill[facet] (0.00000, 0.00000, 1.00000) -- (0.75000, -0.75000, -0.75000) -- (0.75000, 0.75000, -0.75000) -- cycle {};
\fill[facet] (0.00000, 0.00000, 1.00000) -- (-0.75000, 0.75000, -0.75000) -- (0.75000, 0.75000, -0.75000) -- cycle {};
\draw[edge] (-0.75000, -0.75000, -0.75000) -- (0.75000, -0.75000, -0.75000);
\draw[edge] (-0.75000, -0.75000, -0.75000) -- (-0.75000, 0.75000, -0.75000);
\draw[edge] (-0.75000, -0.75000, -0.75000) -- (0.00000, 0.00000, 1.00000);
\draw[edge] (0.75000, -0.75000, -0.75000) -- (0.75000, 0.75000, -0.75000);
\draw[edge] (0.75000, -0.75000, -0.75000) -- (0.00000, 0.00000, 1.00000);
\draw[edge] (-0.75000, 0.75000, -0.75000) -- (0.75000, 0.75000, -0.75000);
\draw[edge] (-0.75000, 0.75000, -0.75000) -- (0.00000, 0.00000, 1.00000);
\draw[edge] (0.75000, 0.75000, -0.75000) -- (0.00000, 0.00000, 1.00000);
\node[vertex] at (-0.75000, -0.75000, -0.75000) {};
\node[vertex] at (0.75000, -0.75000, -0.75000) {};
\node[vertex] at (-0.75000, 0.75000, -0.75000) {};
\node[vertex] at (0.75000, 0.75000, -0.75000) {};
\node[vertex] at (0.00000, 0.00000, 1.00000) {};
\end{tikzpicture}
\end{document}