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(3alleg), create_sub_bitmap(3alleg),
destroy_zbuffer(3alleg)