def update_child(self, matrix):
next_step = mul_tuple(self.direction, self.speed)
next_screen_position = next_point(self.screen_position, next_step)
x, y = s2c(next_screen_position)
if x >= X_CELL_NUM or x < 0 or y >= Y_CELL_NUM or y < 0 or not matrix[y][x]:
# self.direction = STOP
self.direction = TRIGONOMETRY_SUCKS[self.direction]["contr"]
