Pyramide en TikZ

Joaopa · April 2018

Bonjour,

je galère pour réaliser la figure 3D suivante en Tikz:
je voudrais dessiner un repère (0xyz) avec l'axe (Ox) vers l'utilisateur, la pyramide OBCD avec
B(1,0,0), C(0,1,0), D(0,0,1)
et ensuite dessiner en jaune l'intersection de cette pyramide avec le plan d'équation y=0,75.

Si quelqu'un sait comment faire ça...
Merci d'avance.

echec&maths · April 2018

Bonjour,

Tu peux la réaliser sur geogebra puis exporte le code en Latex.

ev · April 2018

En suivant le conseil de Echecs+maths

\documentclass[10pt]{article}
\usepackage{pgf,tikz}
\usepackage{mathrsfs}
\usetikzlibrary{arrows}
\pagestyle{empty}
\begin{document}
\definecolor{ffffqq}{rgb}{1.,1.,0.}
\definecolor{ududff}{rgb}{0.30196078431372547,0.30196078431372547,1.}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
\clip(-0.8776011361598561,-0.8483654130134433) rectangle (1.6932114712962034,1.1566873776609077);
\fill[line width=2.pt,color=ffffqq,fill=ffffqq,fill opacity=0.5] (0.5859989172193003,-0.12567719883812367) -- (0.75,0.) -- (0.75,0.25) -- cycle;
\draw [line width=2.pt] (0.,1.)-- (1.,0.);
\draw [line width=2.pt] (1.,0.)-- (-0.6560043311227987,-0.5027087953524949);
\draw [line width=2.pt] (-0.6560043311227987,-0.5027087953524949)-- (0.,0.);
\draw [line width=2.pt] (0.,0.)-- (0.,1.);
\draw [line width=2.pt] (0.,1.)-- (-0.6560043311227987,-0.5027087953524949);
\draw [line width=2.pt,color=ffffqq] (0.5859989172193003,-0.12567719883812367)-- (0.75,0.);
\draw [line width=2.pt,color=ffffqq] (0.75,0.)-- (0.75,0.25);
\draw [line width=2.pt,color=ffffqq] (0.75,0.25)-- (0.5859989172193003,-0.12567719883812367);
\draw [line width=2.pt] (0.,0.)-- (1.,0.);
\begin{scriptsize}
\draw [fill=ududff] (1.,0.) circle (2.5pt);
\draw (1.0324040052951742,0.08174372577567433) node {$C$};
\draw [fill=ududff] (0.,1.) circle (2.5pt);
\draw (0.032140649225122706,1.082007081845723) node {$D$};
\draw [fill=ududff] (0.,0.) circle (2.5pt);
\draw (0.032140649225122706,0.08174372577567433) node {$O$};
\draw [fill=ududff] (-0.6560043311227987,-0.5027087953524949) circle (2.5pt);
\draw (-0.7689752513377691,-0.44780746273199845) node {$B$};
\draw [fill=ffffqq] (0.75,0.25) circle (2.5pt);
\draw (0.7834696859112246,0.3352041236938767) node {$M$};
\draw [fill=ffffqq] (0.75,0.) circle (2.5pt);
\draw (0.7834696859112246,0.08174372577567433) node {$N$};
\draw [fill=ffffqq] (0.5859989172193003,-0.12567719883812367) circle (2.0pt);
\draw (0.5933743874725723,-0.1898209862795425) node {$P$};
\end{scriptsize}
\end{tikzpicture}
\end{document}

e.v.

marsup · April 2018

On peut aussi s'y prendre comme ceci :

\documentclass[12pt,tikz]{standalone}
\usetikzlibrary{3d,calc}
\begin{document}
\begin{tikzpicture}
  [
    face/.style={draw=black,fill=blue!50,fill opacity=.7},
    plan/.style={fill=green!60,fill opacity=.7},
    triangle/.style={fill=yellow,fill opacity=.8},
  ]
  \coordinate (o) at (0,0,0) ;
  \coordinate (b) at (1,0,0) ;
  \coordinate (c) at (0,1,0) ;
  \coordinate (d) at (0,0,1) ;

  \def\yy{.75}    % hauteur de la coupure
  \def\x{.5}      % rectangle vert
  \def\y{-\x+.25} % autre dimension
  \begin{scope}[canvas is xz plane at y=\yy]
    \path [plan] (\x,\y) -| (\y,\x) -- cycle;
  \end{scope}
  \begin{scope}
    \clip (d) -- (b) -- (c) -- cycle;
    \path [face] (o) -- (b) -- (d) -- cycle;
    \path [face] (o) -- (d) -- (c) -- cycle;
    \path [face] (o) -- (b) -- (c) -- cycle;
  \end{scope}
  \path [face] (d) -- (b) -- (c) -- cycle;

  \begin{scope}[canvas is xz plane at y=\yy]
    \path [plan] (\x,\y) |- (\y,\x) -- cycle;
    \pgfmathsetmacro{\p}{1-\yy}
    \path [triangle] (0,0) -- (\p,0) -- (0,\p) -- cycle ;
  \end{scope}
  
\end{tikzpicture}
\end{document}

S'il faut changer l'angle de vue, on peut utiliser tikz-3dplot (je peux aider, au besoin.) 75324