# Followup to Restricting the Circular Span of a Radial Tikzpicture

This post is an extension of the post How to Restrict the Circular Span of a Radial Fading Tikzpicture

Consider the code

\documentclass{book}
% Code can be compiled with Pdflatex or Xelatex
\usepackage{tikz}
\definecolor{darkamber}{RGB}{213,54,0}
\definecolor{sunriseyellow}{RGB}{255,219,0}
\definecolor{topaz}{RGB}{255,200,124}

\begin{document}
\thispagestyle{empty}

outer color=transparent!100]
\tikzset{
}

\begin{tikzpicture}
\clip (-3, -3) rectangle (3, 3);
middle color=darkamber!60!sunriseyellow, outer color=darkamber]
(-3, -3) rectangle (3, 3);
\end{tikzpicture}

\vspace*{25pt}

\begin{tikzpicture}
\clip (-3, -3) rectangle (3, 3);
middle color=darkamber!60!sunriseyellow, outer color=darkamber]
(-3, -3) rectangle (3, 3);
\fill[darkamber] (180:4cm) arc (180:360:4cm) -- (0,0) -- cycle; % <---- The pie piece
\end{tikzpicture}
\end{document}


which produces the two images:

I would like to be able to produce the second image in a more expedient manner; e.g., by specifying that the full-circle "radial glow" of the first image should only sweep out 0 degrees to 180 degrees instead of the apparent default 0 degrees to 360 degrees.

The desired second image is obtained by superimposing a darkamber rectangle on the bottom half of the first image.

QUESTION: Is it possible, and if so, how may I modify the code which produces the first image so that it may be specified to produce the glow from (in this case) from 0 degrees to 180 degrees; and more generally, from, say, a degrees to b degrees without having to superimpose a second solid image atop the first to achieve the desired effect? Thank you.

NOTE: In How to Restrict the Circular Span of a Radial Fading Tikzpicture, user SebGlav says, There is a way to restrict, but you need to fill the background before. In any case, you'll have to do it with two commands.''

• I still don't see the point in your question. You fill a square with your background colour, then fill a shape of your own with the shading and it produces what you want. If you want to restrict the shading to a specific shape, then you will not have a coloured background underneath it, unless you filled it before. Maybe could you elaborate about why you need to do these two commands in one, to enlighten us. Jun 21 at 21:35
• @SebGlav I tried to in the posting; perhaps I was not clear enough. Let me try it this way by asking you this---If I wanted to create a radial glow for the portion of the circle, say, 75 le theta le 95 (degrees) , would it not be more expedient, if it were possible, to specify that along the lines I just did, as opposed to trying to figure out how to create the necessary polygon in order to superimpose it on the first image? I do not know if what I am looking for is possible, or feasible from your admonition. In any case, I thought I would ask. Thank you again for your previous answer. Jun 21 at 21:46