How to improve the glowing effect in this figure using TikZ?

I want to improve the glowing effect in the MWE below. As shown in the output there is like a sharp transition between the white circle in the center and the surrounding halo, which does not give the desired effect of having a smooth transition to simulate a natural light. I don't know how TikZ enthusiasts would approach this matter in order to improve the glowing effect? in other words, how far TikZ can go with the glowing effect?

Note
Please keep the diameter of all circles fixed, but you can adjust fading width, the most important point is not to show the empty space at the confluence of the colored circles, I want it to be completely hidden behind the white glowing light, I hope.

MWE Code

\documentclass[border={0pt 0pt 0pt 0pt}]{standalone}
\usepackage{graphicx,xcolor}
\usepackage{pgf,tikz}
\begin{document}
\begin{tikzpicture}[line cap=round,line join=round,very thick,>=triangle 45,x=1.0cm,y=1.0cm,align=center]

\draw [color=black,fill=blue!50!black,fill opacity=1.0] (0,2) circle (1.4cm) node (12oclock){};
\draw [color=black,fill=blue!20!black,fill opacity=1.0] (-1.9,0.62) circle (1.4cm) node (10oclock){};
\draw [color=black,fill=green!50!black,fill opacity=1.0] (-1.18,-1.62) circle (1.4cm) node (8oclock){};
\draw [color=black,fill=orange!50!yellow,fill opacity=1.0] (1.18,-1.62) circle (1.4cm) node (5oclock){};
\draw [color=black,fill=red,fill opacity=1.0] (1.9,0.62) circle (1.4cm) node (2oclock){};
\draw [color=white,fill=white,fill opacity=1] (0,0) circle (0.8cm);

\fill [white,circular glow={fill=white}] (0,0) circle (0.8cm); % the glowing effect

\end{tikzpicture}
\end{document}


MWE Output

• you should also try different pdf viewers just to be sure. – percusse May 17 '14 at 2:04

Edit

Here is a second (better?) solution:

\documentclass[border={0pt 0pt 0pt 0pt}]{standalone}
\usepackage{graphicx,xcolor}
\usepackage{pgf,tikz}

color(0mm)=(white);
color(3mm)=(white);
color(7mm)=(black);
color(10mm)=(black)
}

\begin{document}
\begin{tikzpicture}[very thick]
\draw [draw=black,fill=blue!50!black,fill opacity=1.0] (0,2) circle (1.4cm) node (12oclock){};
\draw [draw=black,fill=blue!20!black,fill opacity=1.0] (-1.9,0.62) circle (1.4cm) node (10oclock){};
\draw [draw=black,fill=green!50!black,fill opacity=1.0] (-1.18,-1.62) circle (1.4cm) node (8oclock){};
\draw [draw=black,fill=orange!50!yellow,fill opacity=1.0] (1.18,-1.62) circle (1.4cm) node (5oclock){};
\draw [draw=black,fill=red,fill opacity=1.0] (1.9,0.62) circle (1.4cm) node (2oclock){};

\end{tikzpicture}
\end{document}


First proposition

Here is a solution:

\documentclass[border={0pt 0pt 0pt 0pt}]{standalone}
\usepackage{graphicx,xcolor}
\usepackage{pgf,tikz}
\begin{document}
\begin{tikzpicture}[very thick]
\draw [draw=black,fill=blue!50!black,fill opacity=1.0] (0,2) circle (1.4cm) node (12oclock){};
\draw [draw=black,fill=blue!20!black,fill opacity=1.0] (-1.9,0.62) circle (1.4cm) node (10oclock){};
\draw [draw=black,fill=green!50!black,fill opacity=1.0] (-1.18,-1.62) circle (1.4cm) node (8oclock){};
\draw [draw=black,fill=orange!50!yellow,fill opacity=1.0] (1.18,-1.62) circle (1.4cm) node (5oclock){};
\draw [draw=black,fill=red,fill opacity=1.0] (1.9,0.62) circle (1.4cm) node (2oclock){};
}
\end{tikzpicture}
\end{document}

• to be honest, I was about to ask you for the second solution, which is definitely better, thanks a lot. – doctorate May 17 '14 at 12:22

It is dark during night isn't it?

\documentclass[border={0pt 0pt 0pt 0pt}]{standalone}
\usepackage{graphicx,xcolor}
\usepackage{pgf,tikz}
\begin{document}
\begin{tikzpicture}[line cap=round,line join=round,very thick,>=triangle 45,x=1.0cm,y=1.0cm,align=center]

\draw [fill=blue!50!black,fill opacity=1.0] (0,2) circle (1.4cm) node (12oclock){};
\draw [fill=blue!20!black,fill opacity=1.0] (-1.9,0.62) circle (1.4cm) node (10oclock){};
\draw [fill=green!50!black,fill opacity=1.0] (-1.18,-1.62) circle (1.4cm) node (8oclock){};
\draw [fill=orange!50!yellow,fill opacity=1.0] (1.18,-1.62) circle (1.4cm) node (5oclock){};
\draw [fill=red,fill opacity=1.0] (1.9,0.62) circle (1.4cm) node (2oclock){};
%%\path [fill=white,fill opacity=1] (0,0) circle (0.7cm);  %% optional may remove it.

\fill[black, path fading=fade inside] (current bounding box.south west) rectangle  (current bounding box.north east); % the glowing effect
\end{tikzpicture}

\end{document}


Just 4 fun with PSTricks.

\documentclass[pstricks,border=12pt]{standalone}
\usepackage{multido}

\def\glower#1#2#3{%
\pscustom[linestyle=none,fillcolor=white,opacity=#3,fillstyle=eofill]
{
\pscircle{!4 1 #1 sub mul}
\moveto(!4 1 #2 sub mul 0)
\pscircle{!4 1 #2 sub mul}
}}

\begin{document}

\begin{pspicture}[fillstyle=solid,dimen=m](-5,-5)(5,5)
\foreach \a/\c in {18/red,90/blue,162/black,234/green,306/yellow}{\pscircle[fillcolor=\c](2;\a){2}}
\multido{\nO=0.00+0.01,\nI=0.01+0.01}{81}{\glower{\nI}{\nO}{\nO}}\glower{1}{.81}{1}
\end{pspicture}
\end{document}


Version 2

\documentclass[pstricks,border=12pt]{standalone}
\usepackage{multido}

\def\glower#1#2#3{%
\pscustom[linestyle=none,fillcolor=white,opacity=#3,fillstyle=eofill]
{
\pscircle{!3 1 #1 sub mul}
\moveto(!3 1 #2 sub mul 0)
\pscircle{!3 1 #2 sub mul}
}}

\begin{document}

\begin{pspicture}[fillstyle=solid,dimen=m](-5,-5)(5,5)
\foreach \a/\c in {18/red,90/blue,162/black,234/green,306/yellow}{\pscircle[fillcolor=\c](2.5;\a){2}}
\multido{\nO=0.000+0.001,\nI=0.001+0.001,\n=0.0000+0.0015}{501}{\glower{\nI}{\nO}{\n}}\glower{1}{.501}{1}
\end{pspicture}
\end{document}


• \moveto(!4 1 #2 sub mul 0) is still needed because \pscircle and \psellipse do not move the current point to its starting point before drawing. – kiss my armpit May 17 '14 at 12:28