> 球を空間座標内に書き表したいのですが，
> 球に内接する四面体を書きたいのですが・・・
思わず反応しました。

\documentclass[b5j]{jarticle}

\usepackage[papersize]{emath}
\usepackage{emathP}

\pagestyle{empty}

\begin{document}
\Drawaxisfalse%
%%%%%%%%%%%%%%%%%%%
\unitlength=10mm
\def\Cnt{20}%<= 描画分割数[多いほど細かい(時間がかかる)]
\def\R{2}%<= 球の半径
\def\IniAngle{35}%<= 三角錐のねじれ位置
\rtenretu*{Ex(1,200)}%<= X軸単位ベクトル
\rtenretu*{Ey(1,-20)}%<= Y軸単位ベクトル
\rtenretu*{Ez(1.2,90)}%<=Z軸単位ベクトル[長さ1にするとつぶれて見えます]
%%%%%%%%%%%%%%%%%%%
\Div\R{3}\RH
\begin{Zahyou}[\Ex][\Ey][\Ez](-4,4)(-4,4)(-4,4){}%
\Div\R\Cnt\H%
\Ifor\ICnt{0}\Cnt\Do{%
\Mul\H\ICnt\TT%
\calcval{sqrt(\R**2-\TT**2)}\GR%
\def\Fx{\GR*cos(T)}%
\def\Fy{\GR*sin(T)}%
\iiiBGurafu(0.05)(0.01)\Fx\Fy\TT{0}{2*$pi}
\iiiBGurafu(0.05)(0.02)\Fx\Fy{-\TT}{0}{2*$pi}
}
\def\O{(0,0,\R)}%
\calcval{\IniAngle*$pi/180}\KakuA%
\calcval{sqrt(8)/3*\R*cos(\KakuA)}\Ax%
\calcval{sqrt(8)/3*\R*sin(\KakuA)}\Ay%
\def\A{(\Ax,\Ay,-\RH)}%
\calcval{(\IniAngle+120)*$pi/180}\KakuB%
\calcval{sqrt(8)/3*\R*cos(\KakuB)}\Bx%
\calcval{sqrt(8)/3*\R*sin(\KakuB)}\By%
\def\B{(\Bx,\By,-\RH)}%
\calcval{(\IniAngle-120)*$pi/180}\KakuC%
\calcval{sqrt(8)/3*\R*cos(\KakuC)}\Cx%
\calcval{sqrt(8)/3*\R*sin(\KakuC)}\Cy%
\def\C{(\Cx,\Cy,-\RH)}%
\Thicklines%
\iiiDrawline{\O\A}%
\iiiDrawline{\O\B}%
\iiiDrawline{\O\C}%
\iiiDrawline{\A\B}%
\iiiDrawline{\C\A}%
\thicklines%
\iiiDashline[100]{0.2}{\B\C}
\end{Zahyou}%
\end{document}%

▼関連発言
│
└◆4421:空間座標で [taka] 03/03 14:49
　└◆4422:Re:空間座標で [田中徹] 03/03 18:55<-last