# Hide a part of a graph

How to hide a part of a torus. I mean in the following torus

ParametricPlot3D[{ (3 + Cos[v]) Sin[u], (3+ Cos[v]) Cos[u], Sin[v]}, {u, 0, 2 Pi}, {v, 0, 2 Pi}]

I want to hide the shaded part

• Try {u, -Pi/8, Pi/8}. Is that what you mean? – Rohit Namjoshi Jun 20 '19 at 5:33

Simplest way is to change the u range as suggested by Rohit in comments.

Using RegionFunction:

ParametricPlot3D[{(3 + Cos[v]) Sin[u], (3 + Cos[v]) Cos[u],
Sin[v]}, {u, -Pi, Pi}, {v, 0, 2 Pi},
RegionFunction -> (-Pi + Pi/16 <= #4 <= Pi - Pi/16 &)]


ParametricPlot3D[{(3 + Cos[v]) Sin[u], (3 + Cos[v]) Cos[u],
Sin[v]}, {u, -Pi, Pi}, {v, 0, 2 Pi}, MeshFunctions -> {#4 &},
Mesh -> {{-Pi + Pi/16, Pi - Pi/16}},