Origin for polar coordinates

[Sebastián PEÑA SALDARRIAGA]

Hi pgf users,

I saw this example in Kjell Magne's site (
http://www.texample.net/tikz/examples/rgb-color-mixing/ ). I have a
question about the following code :

\foreach \x in {0,0.0111,...,1} {
        \definecolor{currentcolor}{hsb}{\x, 1, 1}
        \draw[draw=none, fill=currentcolor]
                (-360*\x+88:2) -- (-360*\x+88:3.8)
                -- (-360*\x+92:3.8) -- (-360*\x+92:2) -- cycle;
}

How can I specify the origin for polar coordinates ? Actually, I want to
do some absolute positioning by changing the center of the circle.

Thanks

Sebastian

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[Kjell Magne Fauske]

2009/9/16 Sebastián Peña Saldarriaga
<sebastian.pena-saldarriaga@...>:

> Hi pgf users,
>
> I saw this example in Kjell Magne's site (
> http://www.texample.net/tikz/examples/rgb-color-mixing/ ). I have a
> question about the following code :
>
> \foreach \x in {0,0.0111,...,1} {
>        \definecolor{currentcolor}{hsb}{\x, 1, 1}
>        \draw[draw=none, fill=currentcolor]
>                (-360*\x+88:2) -- (-360*\x+88:3.8)
>                -- (-360*\x+92:3.8) -- (-360*\x+92:2) -- cycle;
> }
>
> How can I specify the origin for polar coordinates ? Actually, I want to
> do some absolute positioning by changing the center of the circle.
>

Transformations are your friends here. You can for instance use a scope:

\begin{scope}[shift=(x,y)]
...
\end{scope}
(where x,y is the coordinate of the origin)

You can also apply a transformation directly to the path:

        \draw[draw=none, fill=currentcolor, shift=(x,y)]
                (-360*\x+88:2) -- (-360*\x+88:3.8)
                -- (-360*\x+92:3.8) -- (-360*\x+92:2) -- cycle;


- Kjell Magne Fauske

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is the only developer event you need to attend this year. Jumpstart your
developing skills, take BlackBerry mobile applications to market and stay
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http://p.sf.net/sfu/devconf
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