# Tikz plots distorted mark

Consider the following code:

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{plotmarks}
\begin{document}
\tikz{\draw (0,0) -- plot[mark=o] (0.5,0) -- (1,0);}
\end{document}


It seems that the mark is not smoothly drawn:

Using the smooth option does not have any effects since the interpolation algorithm only affects line drawing; here the distortion occurs on the marks. Any ideas?

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Welcome to TeX.sx! Could you please add a Minimal Working Example (MWE), that is a complete code that demonstrates the problem (incl any packages that are read). – Peter Jansson Jan 6 '13 at 18:30
@rkmylo maybe you could add \pgfuseplotmark{o} to your example, to show the difference (which i can see too). – bloodworks Jan 6 '13 at 18:56
@zeroth you are wrong. zooming in does not remove the distortion. I have made a similar question here. In the link I pointed, observe the difference between the triangle mark in the actual plot and the corresponding triangle mark shown in the legend. Both, have been drawn using tikz/pgf and the one is smoothly drawn, while the other is not. – rkmylo Jan 6 '13 at 19:07
@zeroth the image shown in my post is from TexShop viewer with 1000% zoom. I also tried Adobe Reader with 6400% zoom and the difference is still obvious. – rkmylo Jan 6 '13 at 19:16
@zeroth to make the difference as clear as possible, take a look at these two pictures 1 2. Both, are shown in Adobe Reader with 6400% zoom. – rkmylo Jan 6 '13 at 19:28

You're using the wrong syntax for plotting a point: plot (0.5,0) is assumed to be a function, so it's evaluated several times (depending on the sample number), and several instances of your point are plotted on top of each other. Fixes: Either set samples at=1 to make sure your point is only plotted once, or use the official syntax for plotting points, which is plot coordinates {(0.5,0)}

\documentclass[border=2mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{plotmarks}
\begin{document}
\tikz{\draw (0,0) -- plot[mark=o] (0.5,0) -- (1,0);}
\tikz{\draw (0,0) -- plot[samples at={1}, mark=o] (0.5,0) -- (1,0);}
\tikz{\draw (0,0) -- plot[mark=o] coordinates {(0.5,0)} -- (1,0);}
\end{document}

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@Jake thank you very much. The coordinates keyword indeed solves the problem (enables anti-aliasing). – rkmylo Jan 6 '13 at 19:43