al_set_clipping_rectangle - Man Page

#include <allegro5/allegro.h>

void al_set_clipping_rectangle(int x, int y, int width, int height)

Set the region of the target bitmap or display that pixels get clipped to. The default is to clip pixels to the entire bitmap.

al_get_clipping_rectangle(3), al_reset_clipping_rectangle(3)

al_clear_depth_buffer(3), al_clear_to_color(3), al_draw_multiline_text(3), al_get_clipping_rectangle(3), al_reset_clipping_rectangle(3).