In computer graphics, clamping is the process of limiting a position to an area. Unlike wrapping

Wrapping (graphics)

In computer graphics, wrapping is the process of limiting a position to an area. A good example of wrapping is wallpaper, a single pattern repeated indefinitely over a wall...

, clamping merely moves the point to the nearest available value.

To put clamping into perspective, pseudocode

Pseudocode

In computer science and numerical computation, pseudocode is a compact and informal high-level description of the operating principle of a computer program or other algorithm. It uses the structural conventions of a programming language, but is intended for human reading rather than machine reading...

 for clamping is:
function clamp(X, Min, Max:Real):Real;
if X > Max then
X := Max;
if X < Min then
X := Min;
return X;

In JavaScript

JavaScript

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

:

function clamp(value, min, max) {
return Math.min(Math.max(value, min), max);
};

A faster one in JavaScript

JavaScript

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

 using ternary operators

?:

In computer programming, ?: is a ternary operator that is part of the syntax for a basic conditional expression in several programming languages...

:

function clamp(value, min, max) {
return value < min ? min : value > max ? max : value;
}

C and C++: (int

Integer (computer science)

In computer science, an integer is a datum of integral data type, a data type which represents some finite subset of the mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values....

 can be changed into any other datatype):

int clamp(int X, int Min, int Max)
{
if( X > Max )
X = Max;
else if( X < Min )
X = Min;

return X;
}

or

int clamp(int X, int Min, int Max) {
return ( X > Max ) ? Max : ( X < Min ) ? Min : X;
}

or

int clamp(int X, int Min, int Max)
{
if ( X > Max ) return Max;
if ( X < Min ) return Min;

return X;
}

or, using templates to cover all data types (C++ only)

template<typename T>
T clamp(T Value, T Min, T Max)
{
return (Value < Min)? Min : (Value > Max)? Max : Value;
}

Uses

One of the many uses of clamping in computer graphics

3D computer graphics

3D computer graphics are graphics that use a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images...

 is the placing of a detail inside a polygon—for example, a bullethole on a wall. It can also be used with wrapping

Wrapping (graphics)

In computer graphics, wrapping is the process of limiting a position to an area. A good example of wrapping is wallpaper, a single pattern repeated indefinitely over a wall...

to create a variety of effects.

Can also mean clamped to a certain value. For example, in OpenGL, the glClearColor takes a GLclampf value which is a gl float value 'clamped' to the range [0,1].