Wrapping (graphics)

{{About|the technique used in 3D graphics|wrapping in word processing|Word wrap}}

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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. Wrapping is used in 3D computer graphics to repeat a texture over a polygon, eliminating the need for large textures or multiple polygons.

To wrap a position x to an area of width w, calculate the value $x' = x \text{ mod } w$ .

Implementation

For computational purposes the wrapped value x' of x can be expressed as

: $x' = x - \lfloor (x - x_{\text{min}}) / (x_{\text{max}} - x_{\text{min}}) \rfloor \cdot (x_{\text{max}} - x_{\text{min}})$

where $x_{\text{max}}$ is the highest value in the range, and $x_{\text{min}}$ is the lowest value in the range.

Pseudocode for wrapping of a value to a range other than 0–1 is

function wrap(X, Min, Max: Real): Real;

X := X - Int((X - Min) / (Max - Min)) * (Max - Min);

if X < 0 then // This corrects the problem caused by using Int instead of Floor

X := X + Max - Min;

return X;

Pseudocode for wrapping of a value to a range of 0–1 is

function wrap(X: Real): Real;

X := X - Int(X);

if X < 0 then

X := X + 1;

return X;

Pseudocode for wrapping of a value to a range of 0–1 without branching is,

function wrap(X: Real): Real;

return ((X mod 1.0) + 1.0) mod 1.0;

Wrapping (graphics)

Implementation

See also