How to add loops winding all the way around the torus and simple loops to this torus:
\documentclass[tikz,border=1.14mm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.15}
\begin{document}
\begin{tikzpicture}[scale=0.5]
\begin{axis}[colormap/blackwhite,
view={30}{60},axis lines=none
]
\addplot3[surf,opacity=0.7,
samples=50, point meta=x+3*z*z-0.25*y,
domain=0:2*pi,y domain=0:2*pi,
z buffer=sort]
({(3+cos(deg(x)))*cos(deg(y))},
{(3+cos(deg(x)))*sin(deg(y))},
{sin(deg(x))});
\end{axis}
\end{tikzpicture}
\end{document}


