“Wrapping (graphics)”的意思、由来-开放百科全书

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Wrapping (graphics)

释义

Implementation
See also

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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 .

Implementation

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

where is the highest value in the range, and 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;

Implementation

See also