/*
* When the snake eat a fruti its size must be increased by 1 piece. This piece is added in the
* middle so the tail should shift by a position. The direction of this shift depends on the
* current direction of the tail
*/
public void eat() {
// add a new piece to the snake
SnakeTail tail = (SnakeTail) parts.get(parts.size() - 1);
parts.add(parts.size() - 1, new SnakeBody(tail.getX(), tail.getY(), tail.direction));
// shift the tail by 1 position with a direction that depends on its current position.
switch (tail.direction) {
case UP:
tail.moveDown();
break;
case DOWN:
tail.moveUp();
break;
case LEFT:
tail.moveRight();
break;
case RIGHT:
tail.moveLeft();
break;
}
}
/*
* Advance the snake on the grid by a position that depends on the current snake direction.
*/
public void advance() {
int last = parts.size() - 1;
SnakeHead head = (SnakeHead) parts.get(0);
SnakeBody neck = parts.get(1);
SnakeTail tail = (SnakeTail) parts.get(last);
// move all the snake pieces but head, one step forward
for (int i = last; i > 0; i--) {
SnakeBody before = parts.get(i - 1);
SnakeBody part = parts.get(i);
part.setX(before.getX());
part.setY(before.getY());
part.direction = before.direction;
}
// move the head towards the snake direction.
head.direction = direction;
switch (direction) {
case UP:
head.moveUp();
break;
case LEFT:
head.moveLeft();
break;
case DOWN:
head.moveDown();
break;
case RIGHT:
head.moveRight();
break;
}
// determine the neck direction
switch (neckDirection) {
case UP_RIGHT:
case LEFT_UP:
case DOWN_LEFT:
case RIGHT_DOWN:
case LEFT_DOWN:
case UP_LEFT:
case DOWN_RIGHT:
case RIGHT_UP:
neck.direction = neckDirection;
neckDirection = Direction.UP;
break;
}
// determine the tail direction
switch (tail.direction) {
case DOWN_LEFT:
case UP_LEFT:
tail.direction = Direction.LEFT;
break;
case LEFT_UP:
case RIGHT_UP:
tail.direction = Direction.UP;
break;
case RIGHT_DOWN:
case LEFT_DOWN:
tail.direction = Direction.DOWN;
break;
case UP_RIGHT:
case DOWN_RIGHT:
tail.direction = Direction.RIGHT;
break;
}
}