ants.py

    def visible(self, loc):
        ' determine which squares are visible to the given player '

        if self.vision == None:
            if not hasattr(self, 'vision_offsets_2'):
                # precalculate squares around an ant to set as visible
                self.vision_offsets_2 = []
                mx = int(sqrt(self.viewradius2))
                for d_row in range(-mx,mx+1):
                    for d_col in range(-mx,mx+1):
                        d = d_row**2 + d_col**2
                        if d <= self.viewradius2:
                            self.vision_offsets_2.append((
                                d_row%self.rows-self.rows,
                                d_col%self.cols-self.cols
                            ))
            # set all spaces as not visible
            # loop through ants and set all squares around ant as visible
            self.vision = [[False]*self.cols for row in range(self.rows)]
            for ant in self.my_ants():
                a_row, a_col = ant
                for v_row, v_col in self.vision_offsets_2:
                    self.vision[a_row+v_row][a_col+v_col] = True
        row, col = loc
        return self.vision[row][col]