int footprint(int radius2, coord_def pos[]) const;

// Shoot a ray from the given start point (accx, accy) with the given
// slope, bounded by the given pre-squared LOS radius.
// Store the visited cells in pos[], and
// return the number of cells visited.
int ray_def::footprint(int radius2, coord_def cpos[]) const
{
    ray_def copy = *this;
    coord_def c;
    int cellnum;
    for (cellnum = 0; true; ++cellnum)
    {
        copy.raw_advance();
        c = copy.pos();
        if (c.abs() > radius2)
            break;
        cpos[cellnum] = c;
    }
    return cellnum;
}