# 3d plot with absolute value function with pstricks

I would like to reproduce the plot given in picture. The function (with known a and c) is

a(x^2+y^2+z^2)+(1-a)(abs(x)+abs(y)+abs(z))=c where 0<a<1, c>0


How can I do this?

\documentclass[pstricks]{standalone}
\usepackage{pst-solides3d}
\begin{document}
\begin{pspicture}(-6,-4)(6,6)
\psset{lightsrc=5 50 30 rtp2xyz,viewpoint=50 60 15 rtp2xyz,Decran=50}
\psImplicitSurface[ % a=0.5 c=2
XMinMax=-2.0 2.0 0.1,YMinMax=-2.0 2.0 0.1,ZMinMax=-2.0 2.0 0.1,
algebraic,
ImplFunction=0.5*(x^2+y^2+z^2)+(1-0.5)*(abs(x)+abs(y)+abs(z))-2,
fillcolor=red,
grid]%
\gridIIID[Zmin=-2,Zmax=2](-2,2)(-2,2)
\end{pspicture}
\end{document}