Intersects a bitmap's clipping rectangle with the given area. allegro game programming library.
#include <allegro.h>
void add_clip_rect(BITMAP *bitmap, int x1, int y1, int x2, int y2);
Sets the clipping rectangle of the specified bitmap as the intersection of its current clipping rectangle and the rectangle described by the four coordinates.
set_clip_rect(3alleg4), get_clip_rect(3alleg4), set_clip_state(3alleg4), get_clip_state(3alleg4)