Trisha Shetty (Editor)

Wrapping (graphics)

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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 ( mod w ) .

Implementation

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

x = x ( x x m i n ) / ( x m a x x m i n ) ( x m a x x m i n )

where x m a x is the highest value in the range, and x m i n 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;

References

Wrapping (graphics) Wikipedia