pivot_sprite - Rotates a sprite around a specified point. Allegro game
programming library.
#include <allegro.h>
void pivot_sprite(BITMAP *bmp, BITMAP *sprite, int x, int y, int cx,
int cy, fixed angle);
Like rotate_sprite(), but aligns the point in the sprite given by (cx,
cy) to (x, y) in the bitmap, then rotates around this point.
rotate_sprite(3alleg), pivot_scaled_sprite(3alleg),
pivot_sprite_v_flip(3alleg), exsprite(3alleg)