shading circular sector

Question

I want to shade the predefined node shape "circular sector" pgfman301a,p 706, from the marked anchor points (sector center and arc center). The draw is based on pgfman301a,p.686. It's "on axis" drawing but not possible for me.

   \documentclass[]{standalone}
   \usepackage{tikz}
   \usetikzlibrary{mindmap,%to get annotations
            decorations.fractals,
            decorations.pathmorphing,
            decorations.text,
            positioning,
            fadings,lindenmayersystems,
            shadings,calendar,spy,math,calc,
            shapes.geometric,
            shadows,
            fadings,backgrounds}

\begin{document}  
\begin{tikzpicture}[scale=0.5,
                    transform shape
                   ] 

\tikzset{shape circlesec/.style={bottom color=red,
                                 middle color=green,
                                 top color=white,
                                 shade,
                                 shading=axis,
                                 shading angle=180,
                                 draw,
                                 %fill=yellow!30,
                                 line width=0.1pt,
                                 inner xsep=0pt,
                                 inner ysep=0pt,
    } 
}%end tikzset


       \node [name=maerz,
       shape=circular sector, 
       style=shape circlesec,
       inner sep=0cm,
       circular sector angle=30,
       shape border uses incircle,
       shape border rotate=-165,
       anchor=sector center,inner sep=-2mm,%
       minimum size = 6.6cm,%has an effect if the original size was smaller
       shading angle=60,
      ] 
   (maerz) at (0,0) {};

   %\draw[top color=white,bottom color=black,middle color=violet]%
   %   (maerz.arc center) circular sector  (maerz.sector center);

   \foreach \anchor/\placement in
      {arc center/right, sector center/below left}
      \draw[shift=(maerz.\anchor)] plot[mark=x] coordinates{(0,0)}
         node[\placement] {\scriptsize\texttt{(maerz.\anchor)}};

   \draw let \p1=($(maerz.north)-(maerz.sector center)$),\n1={int(1+\y1*1pt/1cm)}%
      in
      \pgfextra{\pgfmathtruncatemacro{\xmax}{\n1}
                \pgfmathtruncatemacro{\nextx}{\xmax-1}
               }%end pgfextra code
      foreach \x in {-\xmax,-\nextx,...,\xmax}
         {(\x,1pt) -- (\x,-1pt) node[anchor=north,font=\tiny]{ $\x$} } 
      foreach \y in {-\xmax,-\nextx,...,\xmax}
         {(1pt,\y) -- (-1pt,\y) node[anchor=east,font=\tiny]{($\y$)}};

\end{tikzpicture} 
\end{document}\grid

the violet draw works and one can see how the rotate angle should work. but i cannot. seems to need more.

 \documentclass[]{standalone}

  \usepackage{tikz}

  \usetikzlibrary{calc,shapes.geometric,backgrounds}

\begin{document}  
\begin{tikzpicture}[scale=0.5,
                    transform shape
                   ] 

\tikzset{shape circlesec/.append style={bottom color=red,
                                 top color=green,
                                 middle color=white,
                                 shade,
                                 shading=axis,
                                 draw,
                                 line width=0.1pt,
                                 inner xsep=0pt,
                                 inner ysep=0pt,
    } 
}%end tikzset


       \node [name=maerz,
       shape=circular sector, 
       style=shape circlesec,
       inner sep=0cm,
       circular sector angle=30,
       shape border uses incircle,
       shape border rotate=-165,
       anchor=sector center,inner sep=-2mm,%
       minimum size = 6.6cm,%has an effect if the original size was smaller
       shading angle=15,
      ] 
   (maerz) at (0,0) {};

   \draw[shade,shading angle=15,shading=axis,top color=white,bottom color=black,middle color=violet]%
      (maerz.arc center) rectangle  (maerz.sector center);

   \foreach \anchor/\placement in
      {arc center/right, sector center/below left}
      \draw[shift=(maerz.\anchor)] plot[mark=x] coordinates{(0,0)}
         node[\placement] {\scriptsize\texttt{(maerz.\anchor)}};

   \draw let \p1=($(maerz.north)-(maerz.sector center)$),\n1={int(1+\y1*1pt/1cm)}%
      in
      \pgfextra{\pgfmathtruncatemacro{\xmax}{\n1}%set var xmax from value of n1 s.a.
                \pgfmathtruncatemacro{\nextx}{\xmax-1}
               }%end pgfextra code
      foreach \x in {-\xmax,-\nextx,...,\xmax}
         {(\x,1pt) -- (\x,-1pt) node[anchor=north,font=\tiny]{ $\x$} } 
      foreach \y in {-\xmax,-\nextx,...,\xmax}
         {(1pt,\y) -- (-1pt,\y) node[anchor=east,font=\tiny]{($\y$)}};

\end{tikzpicture} 
\end{document}

above code generates the violet draw (progr. inconvenient)

Could you please try to make the question a bit clearer? Your code produces a shaded segment. What precisely do you want to change? (and out of all the libraries you load you only need \usetikzlibrary{calc,shapes.geometric} and \grid after \end{document} can probably be dropped.) — , Jan 05 '19 at 23:35
top color should begin at arc center, middle color follows to bottom color at sector center or v.v. pgfman says draw along a path you can shade this path. so i want to draw between these coords. — gizeh, Jan 05 '19 at 23:54
I see how this can be confusing. You need to add the colors in the right order: bottom color=red,top color=white,middle color=green,. Ironically, middle color cannot be in the middle. — , Jan 06 '19 at 00:01
i have changed it and right green has appeared. but is it possible by angle rotate(i see no effect?) or something else to make as mentioned above the sequence of the colors shading from centre to out (petal). — gizeh, Jan 06 '19 at 00:08
I do not really understand your comment. Yes, there is radial shading. Do you want to use that? (If not, consider using a shading angle of 15, which seems more appropriate than 60 for this shape.) BTW, you set the shading angle twice: once in the definition of shape circlesec and then when you actually draw the node. The second setting overrides the first one. — , Jan 06 '19 at 00:10

score 5 · Accepted Answer · 2019-01-06T01:17:27.593

Here is some radial shading. A 3-color radial shading has been proposed in this very nice answer. However, I was unable to make the middle color very visible, even though I played with the parameters. Well, all I can say is that the author of this nice shading left a question "later - shading is assumed to be 100bp diameter ??". If she does not know, how would a poor marmot know, in particular during hibernation time? I copied the code such that you or others can play with it.

Luckily you want the middle color to be white, so I could use plan B, which is path fading in this case. So that's my proposal.

\documentclass[tikz]{standalone}
\makeatletter
% from https://tex.stackexchange.com/a/127045/121799
\tikzset{use path/.code=\tikz@addmode{\pgfsyssoftpath@setcurrentpath#1}}
\makeatother
\usetikzlibrary{calc,shapes.geometric,backgrounds,fadings}
\tikzfading[name=fade in,
inner color=transparent!100,
outer color=transparent!0]

\pgfdeclareradialshading[fradialcolour1,fradialcolour2,fradialcolour3]{fncyradial}{\pgfpoint{0}{0}}{% manual 1082-1083; later - shading is assumed to be 100bp diameter ??
  color(0)=(fradialcolour1);
  color(20bp)=(fradialcolour2);
  color(40bp)=(fradialcolour3);
  color(50bp)=(fradialcolour3)
}
\tikzset{% https://tex.stackexchange.com/a/372682/121799
  fradial/.code={%
        \tikzset{%
          fancy radial/.cd,
          shading=fncyradial,
          #1
        }
  },
  fancy radial/.search also={/tikz},
  fancy radial/.cd,
  fancy radial inner colour/.code={
        \colorlet{fradialcolour1}{#1}
  },
  fancy radial mid colour/.code={
        \colorlet{fradialcolour2}{#1}
  },
  fancy radial outer colour/.code={
        \colorlet{fradialcolour3}{#1}
  },
  fancy radial inner colour=black,
  fancy radial outer colour=black,
  fancy radial mid colour=white,
  inner color/.style={
        fancy radial inner colour=#1,
  },
  outer color/.style={
        fancy radial outer colour=#1,
  },
  mid color/.style={
        fancy radial mid colour=#1,
  },
}
\begin{document}  
\begin{tikzpicture}[scale=0.5,
                    transform shape
                   ] 

\tikzset{shape circlesec/.style={
                                 draw,
                                 line width=0.1pt,
                                 inner xsep=0pt,
                                 inner ysep=0pt,
    } 
}%end tikzset


       \node [name=maerz,save path=\pathA,
       shape=circular sector, 
       style=shape circlesec,
       inner sep=0cm,
       circular sector angle=30,
       shape border uses incircle,
       shape border rotate=-165,
       anchor=sector center,inner sep=-2mm,%
       minimum size = 6.6cm,%has an effect if the original size was smaller
       %shading angle=15,
      ] 
   (maerz) at (0,0) {};
   \begin{scope}[on background layer]
   \clip[use path=\pathA];
   \shade[inner color=green,outer color=red,path fading=fade in] let 
   \p1=($(maerz.arc center)-(maerz.sector center)$),\n1={veclen(\y1,\x1)}
   in (maerz.sector center) circle (\n1);
   \end{scope}
   \foreach \anchor/\placement in
      {arc center/right, sector center/below left}
      \draw[shift=(maerz.\anchor)] plot[mark=x] coordinates{(0,0)}
         node[\placement] {\scriptsize\texttt{(maerz.\anchor)}};

   \draw let \p1=($(maerz.north)-(maerz.sector center)$),\n1={int(1+\y1*1pt/1cm)}%
      in
      \pgfextra{\pgfmathtruncatemacro{\xmax}{\n1}
                \pgfmathtruncatemacro{\nextx}{\xmax-1}
               }%end pgfextra code
      foreach \x in {-\xmax,-\nextx,...,\xmax}
         {(\x,1pt) -- (\x,-1pt) node[anchor=north,font=\tiny]{ $\x$} } 
      foreach \y in {-\xmax,-\nextx,...,\xmax}
         {(1pt,\y) -- (-1pt,\y) node[anchor=east,font=\tiny]{($\y$)}};

\end{tikzpicture} 
\end{document}

Of course, you could add another color by superimposing \tikzfading[name=fade out,inner color=transparent!0,outer color=transparent!100] from p. 344 of the pgfmanual.

OLD ANSWER: When using shadings, ironically the middle color has to come last, and not in the middle.

\documentclass[]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc,shapes.geometric}

\begin{document}  
\begin{tikzpicture}[scale=0.5,
                    transform shape
                   ] 

\tikzset{shape circlesec/.style={bottom color=red,
                                 top color=white,
                                 middle color=green,
                                 shade,
                                 shading=axis,
                                 shading angle=180,
                                 draw,
                                 %fill=yellow!30,
                                 line width=0.1pt,
                                 inner xsep=0pt,
                                 inner ysep=0pt,
    } 
}%end tikzset


       \node [name=maerz,
       shape=circular sector, 
       style=shape circlesec,
       inner sep=0cm,
       circular sector angle=30,
       shape border uses incircle,
       shape border rotate=-165,
       anchor=sector center,inner sep=-2mm,%
       minimum size = 6.6cm,%has an effect if the original size was smaller
       shading angle=60,
      ] 
   (maerz) at (0,0) {};

   %\draw[top color=white,bottom color=black,middle color=violet]%
   %   (maerz.arc center) circular sector  (maerz.sector center);

   \foreach \anchor/\placement in
      {arc center/right, sector center/below left}
      \draw[shift=(maerz.\anchor)] plot[mark=x] coordinates{(0,0)}
         node[\placement] {\scriptsize\texttt{(maerz.\anchor)}};

   \draw let \p1=($(maerz.north)-(maerz.sector center)$),\n1={int(1+\y1*1pt/1cm)}%
      in
      \pgfextra{\pgfmathtruncatemacro{\xmax}{\n1}
                \pgfmathtruncatemacro{\nextx}{\xmax-1}
               }%end pgfextra code
      foreach \x in {-\xmax,-\nextx,...,\xmax}
         {(\x,1pt) -- (\x,-1pt) node[anchor=north,font=\tiny]{ $\x$} } 
      foreach \y in {-\xmax,-\nextx,...,\xmax}
         {(1pt,\y) -- (-1pt,\y) node[anchor=east,font=\tiny]{($\y$)}};

\end{tikzpicture} 
\end{document}

When playing with your code, I found that these shapes have the unexpected behavior of being resistant to fit....

arc should be read then visible different middle color, centre of circle part third color. have read it whith the sequence in man. nothing help. why the commented draw command doesn't work? i have changed predefined node shape "rectangle" with predefined node shape "circular sector". Coords are valid node anchors — gizeh, Jan 06 '19 at 00:22
@gizeh I added something with radial shading. Do you want something like this? Possibly with a different color in the middle? — , Jan 06 '19 at 00:35
@gizeh What does "that's it" mean? Is the question answered? — , Jan 06 '19 at 00:59
need this third color. cannot decide if i can do it myself right now. if you say easy i willl mark answer as solved soon as possible — gizeh, Jan 06 '19 at 01:15
@gizeh It is IMHO not at all easy nor solved. Those who understand the postcript language in section 109.2.3 General (Functional) Shadings of the pgfmanual may be able to provide you with something that can be used more easily. I can't. I added something that does something that looks like white-green-red, and added a description how one may possible adjust or improve this. That's the best I can do right now. — , Jan 06 '19 at 01:20

shading circular sector

1 Answers1