Function do_clear_area

src/vision.c:2106–2148

* AREA OF EFFECT "ENGINE" * * Calculate all possible visible locations as viewed from the given location * (srow,scol) within the range specified. Perform "func" with (x, y) args and * additional argument "arg" for each square. * * If not centered on the hero, just forward arguments to view_from(); it * will call "func" when necessary. If the hero is the center, use the * vision matrix an

 * vision matrix and reduce extra work.
 */
void
do_clear_area(
    coordxy scol, coordxy srow,
    int range,
    void (*func)(coordxy, coordxy, genericptr_t),
    genericptr_t arg)
{
    /* If not centered on hero, do the hard work of figuring the area */
    if (scol != u.ux || srow != u.uy) {
        view_from(srow, scol, (seenV **) 0, (coordxy *) 0, (coordxy *) 0,
                  range, func, arg);
    } else {
        int x;
        int y, min_x, max_x, max_y, offset;
        const coordxy *limits;
        boolean override_vision;

        /* vision doesn't pass through water or clouds, detection should
           [this probably ought to be an arg supplied by our caller...] */
        override_vision = (detecting(func)
                           && (Is_waterlevel(&u.uz) || Is_airlevel(&u.uz)));

        if (range > MAX_RADIUS || range < 1)
            panic("do_clear_area:  illegal range %d", range);
        if (gv.vision_full_recalc)
            vision_recalc(0); /* recalc vision if dirty */
        limits = circle_ptr(range);
        if ((max_y = (srow + range)) >= ROWNO)
            max_y = ROWNO - 1;
        if ((y = (srow - range)) < 0)
            y = 0;
        for (; y <= max_y; y++) {
            offset = limits[v_abs(y - srow)];
            if ((min_x = (scol - offset)) < 1)
                min_x = 1;
            if ((max_x = (scol + offset)) >= COLNO)
                max_x = COLNO - 1;
            for (x = min_x; x <= max_x; x++)
                if (couldsee(x, y) || override_vision)
                    (*func)(x, y, arg);
        }
    }
}

/* bitmask indicating ways mon is seen; extracted from lookat(pager.c) */
unsigned