
最近 tikz を使い始めたのですが、ラベルの付いた部分を透明にする方法がまったくわかりません。どなたか助けていただければ幸いです。よろしくお願いします。
\usepackage{tikz,tikz-3dplot}
\tdplotsetmaincoords{80}{45}
\tdplotsetrotatedcoords{-90}{180}{-90}
\begin{document}
\begin{figure}[!h]
\centering
\tikzset{surface/.style={draw=blue!70!black, fill=blue!40!white, fill opacity=.6}}
\newcommand{\coneback}[4][]{
\draw[canvas is xy plane at z=#2, #1] (45-#4:#3) arc (45-#4:225+#4:#3) -- (O) --cycle;
}
\newcommand{\conefront}[4][]{
\draw[canvas is xy plane at z=#2, #1] (45-#4:#3) arc (45-#4:-135+#4:#3) -- (O) --cycle;
}
\begin{tikzpicture}[tdplot_main_coords, grid/.style={help lines,blue!40!white,opacity=0.2},scale=1]
\coordinate (O) at (0,0,0);
\fill[blue!40!white,opacity=0.5] (-4,-4,0) -- (-4,4,0) -- (4,4,0) -- (4,-4,0) -- cycle;
\foreach \x in {-4,...,4}
\foreach \y in {-4,...,4}
{
\draw[grid] (\x,-4) -- (\x,4);
\draw[grid] (-4,\y) -- (4,\y);
}
\coneback[surface]{-3}{2}{-12}
\conefront[surface]{-3}{2}{-12}
\draw[->] (-4,0,0) -- (4,0,0) {};
\draw[->] (0,-4,0) -- (0,4,0) {};
\coneback[surface]{3}{2}{12}
\draw[-,dashed] (0,0,-2.65) -- (0,0,2.65) node[above] {};
\draw[-,dashed] (0,0,-4) -- (0,0,-3.35) node[above] {};
\draw[->,dashed] (0,0,3.35) -- (0,0,4) node[above] {$time$};
\conefront[surface]{3}{2}{12}
\fill (4,0,2) circle (2pt) node[above right] {$C$};
\fill (0,0,0) circle (2pt) {};
\fill (-0.5,-0.85,2.2) circle (2pt) node[above left] {$A$};
\fill (1.3,0.5,2) circle (2pt) node[above left] {$B$};
\draw[->,red] (0,0,0) -- (4,0,2) node[below, pos=0.6, rotate=26.5651,scale=0.70,black] {$\textbf{spacelike vector}$};
\draw[->,red] (0,0,0) -- (1.3,0.5,2) node[below, pos=0.65, rotate=55.1459,scale=0.70,black] {$\textbf{lightlike vector}$};
\draw[->,red] (0,0,0) -- (-0.5,-0.85,2.2) node[above, pos=0.57, rotate=-65.8557,scale=0.70,black] {$\textbf{timelike vector}$};
\node[black] at (0,0,3) {$Future\,\,Light\,\,Cone$};
\node[black] at (0,0,-3) {$Past\,\,Light\,\,Cone$};
\node[black] at (0,0.05,0.3) {$O$};
\node[black] at (0,4.7,0) {$space$};
\node[black] at (5,-0.3,0) {$space$};
\end{tikzpicture}
\caption{Light Cone in 2d Space plus a Time Dimension}
\label{cone}
\end{figure}
答え1
まず下の円錐を描きます。次に平面を描き、最後に上の円錐を描きます。青の上に青を描いた場合、前にあるものが見えにくくなるため、配色を変えるのも効果的です。平面の輪郭を描いてコントラストをさらに強めることができます。最後に、時間軸を分割して、過去半分を平面の前に描くようにします。
\begin{figure}[!h]
\centering
\tikzset{surface/.style={draw=blue!70!black, fill=blue!20!white, fill opacity=.6}}
\newcommand{\coneback}[4][]{
\draw[canvas is xy plane at z=#2, #1] (45-#4:#3) arc (45-#4:225+#4:#3) -- (O) --cycle;
}
\newcommand{\conefront}[4][]{
\draw[canvas is xy plane at z=#2, #1] (45-#4:#3) arc (45-#4:-135+#4:#3) -- (O) --cycle;
}
\begin{tikzpicture}[tdplot_main_coords, grid/.style={help lines,violet!40!white,opacity=0.5},scale=1]
\coordinate (O) at (0,0,0);
\coneback[surface]{-3}{2}{-12}
\conefront[surface]{-3}{2}{-12}
\fill[violet!40!white,opacity=0.5] (-4,-4,0) -- (-4,4,0) -- (4,4,0) -- (4,-4,0) -- cycle;
\foreach \x in {-4,...,4}
\foreach \y in {-4,...,4}
{
\draw[grid] (\x,-4) -- (\x,4);
\draw[grid] (-4,\y) -- (4,\y);
\draw[violet] (-4,4)--(-4,-4)--(4,-4)--(4,4)--cycle;
}
\draw[->] (-4,0,0) -- (4,0,0) {};
\draw[->] (0,-4,0) -- (0,4,0) {};
\coneback[surface]{3}{2}{12}
\draw[-,dashed] (0,0,-2.65) -- (0,0,2.65) node[above] {};
\draw[-,dashed] (0,0,-4) -- (0,0,-3.35) node[above] {};
\draw[->,dashed] (0,0,3.35) -- (0,0,4) node[above] {$time$};
\conefront[surface]{3}{2}{12}
\fill (4,0,2) circle (2pt) node[above right] {$C$};
\fill (0,0,0) circle (2pt) {};
\fill (-0.5,-0.85,2.2) circle (2pt) node[above left] {$A$};
\fill (1.3,0.5,2) circle (2pt) node[above left] {$B$};
\draw[->,red] (0,0,0) -- (4,0,2) node[below, pos=0.6, rotate=26.5651,scale=0.70,black] {$\textbf{spacelike vector}$};
\draw[->,red] (0,0,0) -- (1.3,0.5,2) node[below, pos=0.65, rotate=55.1459,scale=0.70,black] {$\textbf{lightlike vector}$};
\draw[->,red] (0,0,0) -- (-0.5,-0.85,2.2) node[above, pos=0.57, rotate=-65.8557,scale=0.70,black] {$\textbf{timelike vector}$};
\node[black] at (0,0,3) {$Future\,\,Light\,\,Cone$};
\node[black] at (0,0,-3) {$Past\,\,Light\,\,Cone$};
\node[black] at (0,0.05,0.3) {$O$};
\node[black] at (0,4.7,0) {$space$};
\node[black] at (5,-0.3,0) {$space$};
\end{tikzpicture}
\caption{Light Cone in 2d Space plus a Time Dimension}
\label{cone}
\end{figure}