% main_3d.tex  LaTeX demonstraton file showing Asymptote 3D, Jim Hefferon
\documentclass{article}
\usepackage{graphicx}
\graphicspath{ {asy/} }  % Trailing slash, dirs in curly braces 
\usepackage{asymptote}  
\def\asydir{asy}  % No trailing slash
% For non-manipulable 3D figures, just compile with "asy vectors" and
% include the PDF output as with 2D figures.
% For manipulable 3D figures: 
% (1) Compile .asy file with "asy -inlineimage vectors". 
% It outputs a number of files, including .tex and .pre files. 
% (2) Include the .pre line here along with one of the lines in center below
\input asy/vectors.pre

\begin{document}
Include the output graphic directly in the text body.
\begin{center}
%   \asyinclude{asy/vectors.asy}  
  \input asy/vectors.tex %
\end{center}  
If you use the commented-out way then run 
\texttt{asy -inlinimage <latex-fn>-1}
between a pair of \LaTeX{} runs of this file.
\end{document}