[Tex/LaTex] Gray shaded sphere with tikz-3dplot

Question

How do I draw a grayscale shaded sphere with tikz-3dplot? I tried using \tdplotsphericalsurfaceplot with radius equal to 1, and parametricfill depending on the spherical angles. However, it looks like I can only prescribe the color's hue (in HSB space), according to the following post, which does not suit me. I could go all the way and redefine \tdplotdosurfaceplot, but that seems overkill.

Let me emphasize that I want true 3D drawing (the rest of my picture requires 3D coordinates: I need to draw arcs), so I cannot use 2D tricks such as

\draw [ball color=white] (0,0,0) circle (1) ;

so this is not a duplicate of how-to-draw-a-shaded-sphere. I explicitly want a 3d drawing, preferably with tikz-3dplot, though I'm open to other 3d packages.

Here are two MWEs: the first sphere uses uniform coloring, while the second uses a linear combination of the spherical angles:

\begin{tikzpicture}[tdplot_main_coords]
\tdplotsphericalsurfaceplot[parametricfill]{24}{24}{1} {black}{50}{}{}{}
\begin{scope}[xshift=4cm]
\tdplotsphericalsurfaceplot[parametricfill]{24}{24}{1} {black}{\tdplottheta+\tdplotphi}{}{}{}
\end{scope}
\end{tikzpicture}

I would also like to get rid of the parametric lines… Maybe this is not the right package to work with, or the right command in the package.

Answer 1

Better use pgfplots (adapted from this post). The parametric fill with \theta+\phi looks pretty weird in my opinion.

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.15}
\begin{document}
\begin{tikzpicture}
  \begin{axis}
    [
      width=6cm,height=6cm,
      axis equal,enlargelimits=false,
      axis lines=none,
      domain=0:180,samples=21,
      y domain=0:360,samples y=21,
      colormap/blackwhite,
      view={100}{10},
    ]
    \addplot3
      [
        surf,
        z buffer=sort,
        shader=flat,
        point meta={acos(z/sqrt(x*x+y*y+z*z)) + atan2(y,x)}
      ] (
        {sin(x)*cos(y)},
        {sin(x)*sin(y)},
        {cos(x)}
      );
  \end{axis}
\end{tikzpicture}
\end{document}