create_sub_zbuffer(3alleg4)      Allegro manual      create_sub_zbuffer(3alleg4)

       create_sub_zbuffer - Creates a sub-z-buffer. Allegro game programming

       #include <allegro.h>

       ZBUFFER *create_sub_zbuffer(ZBUFFER *parent, int x, int y, int width, int

       Creates a sub-z-buffer, ie. a z-buffer sharing drawing memory with a pre-
       existing z-buffer, but possibly with a different size. The same rules as
       for sub-bitmaps apply: the sub-z-buffer width and height can extend
       beyond the right and bottom edges of the parent (they will be clipped),
       but the origin point must lie within the parent region.

       When drawing z-buffered to a bitmap, the top left corner of the bitmap is
       always mapped to the top left corner of the current z-buffer. So this
       function is primarily useful if you want to draw to a sub-bitmap and use
       the corresponding sub-area of the z-buffer. In other cases, eg. if you
       just want to draw to a sub-bitmap of screen (and not to other parts of
       screen), then you would usually want to create a normal z-buffer (not
       sub-z-buffer) the size of the visible screen. You don't need to first
       create a z-buffer the size of the virtual screen and then a sub-z-buffer
       of that.

       Returns the pointer to the sub ZBUFFER or NULL if there was an error.
       Remember to destroy the ZBUFFER once you are done with it, to avoid
       having memory leaks.

       create_zbuffer(3alleg4), create_sub_bitmap(3alleg4),

Allegro                           version 4.4.3      create_sub_zbuffer(3alleg4)