# How to fix TikZ corners in 3D

Am trying to draw a simple rectangle and there seems to be minor issue with two of the endpoints (f and d in the following). I tried line cap=rect as suggested by Bad intersection of lines in TikZ but that did not seem to work. The resulting image:

\documentclass{standalone}
\setlength\PreviewBorder{5pt}%

\usepackage{tikz}

\newcommand*{\Width}{2.0}
\newcommand*{\Height}{3.0}
\newcommand*{\Depth}{1.0}

\begin{document}
\begin{tikzpicture}%
\coordinate (A) at ( 0,       0,     \Depth);%
\coordinate (B) at (\Height,  0,     \Depth);%
\coordinate (C) at (\Height,  0,      0);%
\coordinate (D) at (\Height, \Width,  0);%
\coordinate (E) at ( 0,      \Width,  0);%
\coordinate (F) at ( 0,      \Width, \Depth);%
\coordinate (G) at (\Height, \Width, \Depth);%
\coordinate (H) at ( 0,       0,      0);%
%
\draw [blue, ultra thick,line cap=rect]%
(A) -- (B) -- (C) -- (D) -- (E) -- (F) -- cycle;%
\draw [blue, ultra thick,line cap=rect]%
(B) -- (G) -- (F) -- (E) -- (D) -- (G) -- cycle;%

\path (D)  [right] node {$d$};% Problem Point 1
\path (F)  [left ] node {$f$};% Problem Point 2
\end{tikzpicture}%
\end{document}


This problem about TikZ: changing colour of a path half way along seems related, but I do not understand how to adapt that to my problem.

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Can you include the picture? –  Loop Space Jun 18 '11 at 6:25
Have added a link to the image. –  Peter Grill Jun 18 '11 at 6:58

You should use a different line join type here, either round or bevel, which influences how the corner (not the ends) of lines are drawn:

\begin{tikzpicture}[line join=miter] % Standard option


\begin{tikzpicture}[line join=bevel]


\begin{tikzpicture}[line join=round]


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Yep, that fixed it. Thanks. So is there a reason why I would not want to always use line join=round? I have posted a follow-up question: tex.stackexchange.com/questions/21063/… –  Peter Grill Jun 18 '11 at 8:30
@PeterGrill: If possible, line join=round is probably best. However, it is not always possible depending on how you construct your diagram, I guess. –  Werner Sep 29 '11 at 21:17
@Werner: According to Jake in the question is line join miter the preferable over line join round the miter option should be used unless otherwise needed as is the case here. –  Peter Grill Sep 29 '11 at 21:25