IEnumerator MoveSnake()
{
while (true)
{
yield return(new WaitForSeconds(snake_move_time));
// Calculate next head coordinates
Coordinate head_next_coordinate = CalculateNextTile(head);
TileController head_next = BoardData.GetTile(head_next_coordinate);
snake_next_memory.Add(head, head_next_coordinate);
// if the next is an apple, don't move the tail
if (head_next.tileType == TileType.Apple)
{
EventBus.Publish <SnakeAteAppleEvent>(new SnakeAteAppleEvent());
}
else
{
// Move the tail
MoveTail();
// Only Mark the next head as used if not an apple
BoardData.MarkUsed(head_next);
}
// set sprites
if (head_next_coordinate.x == tail.x && head_next_coordinate.y == tail.y)
{
// if snake_length is 1, don't do fancy sprites
head_next.RemoveSnakeSprite();
}
else
{
BoardData.GetTile(head).SetSnakeSprite(head_next_coordinate, head, prev_head);
head_next.SetSnakeSprite(new Coordinate(-1, -1), head_next_coordinate, head);
BoardData.GetTile(tail).SetSnakeSprite(snake_next_memory[tail], tail, new Coordinate(-1, -1));
}
head_next.SetTileType(TileType.Snake);
// Move the head
snake_length++;
prev_head = head;
head = head_next_coordinate;
if (snake_length == BoardData.GetHeight() * BoardData.GetWidth())
{
EventBus.Publish <BoardFullEvent>(new BoardFullEvent());
}
}
}
void MoveTail()
{
// Clean up
TileController tail_controller = BoardData.GetTile(tail);
Debug.Assert(tail_controller.tileType == TileType.Snake);
BoardData.MarkFree(tail_controller);
tail_controller.RemoveSnakeSprite();
// Move
Coordinate prev_tail = tail;
tail = snake_next_memory[tail];
snake_length--;
snake_next_memory.Remove(prev_tail);
}
Coordinate CalculateNextTile(Coordinate cur)
{
Coordinate next_move = PathGenerator.GetNextTile(cur);
// if the snake is quite large, just return next_move
if (snake_length > BoardData.GetHeight() * BoardData.GetWidth() * 0.6)
{
return(next_move);
}
// calculate potential other paths
List <Coordinate> possible_moves = new List <Coordinate>();
Coordinate p = new Coordinate(cur.x - 1, cur.y);
if (p.x >= 0 && p.x < BoardData.GetWidth() && p.y >= 0 && p.y < BoardData.GetHeight() &&
BoardData.GetTile(p).tileType != TileType.Snake && p != next_move)
{
possible_moves.Add(p);
}
p = new Coordinate(cur.x + 1, cur.y);
if (p.x >= 0 && p.x < BoardData.GetWidth() && p.y >= 0 && p.y < BoardData.GetHeight() &&
BoardData.GetTile(p).tileType != TileType.Snake && p != next_move)
{
possible_moves.Add(p);
}
p = new Coordinate(cur.x, cur.y - 1);
if (p.x >= 0 && p.x < BoardData.GetWidth() && p.y >= 0 && p.y < BoardData.GetHeight() &&
BoardData.GetTile(p).tileType != TileType.Snake && p != next_move)
{
possible_moves.Add(p);
}
p = new Coordinate(cur.x, cur.y + 1);
if (p.x >= 0 && p.x < BoardData.GetWidth() && p.y >= 0 && p.y < BoardData.GetHeight() &&
BoardData.GetTile(p).tileType != TileType.Snake && p != next_move)
{
possible_moves.Add(p);
}
// if surrounded by snake, just return the next step
if (possible_moves.Count == 0)
{
return(next_move);
}
// if we find an apple, just continue down path
while (true)
{
// if we find one of the possible moves, go that way instead
foreach (Coordinate possible_move in possible_moves)
{
if (next_move == possible_move)
{
return(next_move);
}
}
if (BoardData.GetTile(next_move).tileType != TileType.Clear)
{
return(PathGenerator.GetNextTile(cur));
}
next_move = PathGenerator.GetNextTile(next_move);
}
Debug.Assert(false);
return(new Coordinate(-1, -1));
}
