NAME

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

SYNOPSIS

       #include <allegro.h>

       ZBUFFER *create_sub_zbuffer(ZBUFFER *parent, int x, int y, int width, int height);

DESCRIPTION

       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.

RETURN VALUE

       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.

SEE ALSO

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