tikz: Drawing a curve using the \foreach cycle

Question

In tikz: drawing a parametrised curve I asked about drawing a curve using the \pgfplotfunction command.

I could make my code better if I could use the \foreach cycle:

\documentclass{minimal}
\usepackage{tikz}
\usepackage{amsmath}
\begin{document}
\begin{tikzpicture}[x=2cm/2]
  \newcommand\rad{1}
  \pgfplothandlerlineto
  \foreach \phiparam in {0, 1, ..., 360}
           {
             \pgfpointxy{\rad *cos(\phiparam)}{\rad *sin(\phiparam)}
             \pgfusepath{stroke}
           }
\end{tikzpicture}
\end{document}

How to use the \foreach cycle to calculate parameters, plot points and connect them to show a smooth curve?

Do you want to draw a part of an cycle? Maybe helpful: Draw arc in tikz when center of circle is specified — Bobyandbob, Nov 04 '17 at 15:26
No! I really need a cycle because I would like to compute additional variables in its scope. — Viesturs, Nov 04 '17 at 15:29
\pgfusepath can be executed once at the end and path can be added with linetos. — percusse, Nov 04 '17 at 15:34
@percusse Your comment is very valuable. Could you please provide a complete answer. I think one needs to use \pgfpathmoveto in the beginning. — Viesturs, Nov 04 '17 at 16:11

Henri Menke · Accepted Answer · 2017-11-05T02:25:47.077

1

foreach can be part of a path. You only have to unroll the 0-th iteration manually.

\documentclass{article}

\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
  \pgfpathmoveto{\pgfpointxy{cos(0)}{sin(0)}}
  \foreach \phiparam in {1, ..., 360} {
    \pgfpathlineto{\pgfpointxy{cos(\phiparam)}{sin(\phiparam)}}
  }
  \pgfusepath{stroke}
\end{tikzpicture}

\end{document}

In this case plot might be just easier.

\documentclass{article}

\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
  \pgfplothandlerlineto
  \pgfplotfunction{\x}{0,...,360}{\pgfpointxy{cos(\x)}{sin(\x)}}
  \pgfusepath{stroke}
\end{tikzpicture}

\end{document}

edited Nov 05 '17 at 02:25

answered Nov 05 '17 at 00:53

Henri Menke

109,596

This is the approach I needed to circumvent. I am interested to write more complicated commands inside the scope of the cycle. – Viesturs Nov 05 '17 at 01:27
@Viesturs So you want to use the basic layer? It's a bit unclear to me. See updated answer. – Henri Menke Nov 05 '17 at 02:27
The first part of your answer is what I was looking for - a bare \foreach cycle where additional commands can be inserted. – Viesturs Nov 05 '17 at 09:58

tikz: Drawing a curve using the \foreach cycle

1 Answers1