Z-Buffer

Z-Buffer is used by a game engine to determine which objects, or parts of objects, are visible and which are hidden behind other objects.

The graphics processor stores the Z-axis value of each pixel in a special area of memory called the Z-buffer, which is updated constantly.

Different objects can have the same x- and y-coordinate values, but with different z-coordinate values. The object with the lowest z-coordinate value is in front of the other objects, and therefore that's the one that's displayed.

An alternate algorithm for hiding objects behind other objects is called Z-sorting. The Z-sorting algorithm simply displays all objects serially, starting with those objects furthest back (with the largest Z-axis values). The Z-sorting algorithm does not require a Z-buffer, but it is slow and does not render intersecting objects correctly.

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