//removes nodes from the snake
public void shrinkSnake(int amount, GraphicsManager.Direction direction)
{
for (int i = 0; i < amount; i++)
{
if (positions.Count > 0 && positions.Count > Variables.minLength)
{
positions.RemoveAt(positions.Count - 1);
snakeBody.RemoveAt(snakeBody.Count - 1);
snakeBoxes.RemoveAt(snakeBoxes.Count - 1);
directions.RemoveAt(directions.Count - 1);
snakeBody[snakeBody.Count - 1] = GraphicsManager.Instance.getSnakeTexture(direction, GraphicsManager.SnakePart.tail);
}
}
}
public void UpdateSnakePositions(KeyboardState kstate, GameTime gameTime, GraphicsDeviceManager graphics, bool doesIntersect, bool powerUp, bool powerDown)
{
//redraw all collision boxes
UpdateSnakeBoxes();
//check pick up collisions
if (powerUp)
{
if (Variables.fxOn && Variables.audioOn)
{
AudioManager.Instance.playPowerUp();
}
powerUpSnake();
}
if (powerDown)
{
if (Variables.fxOn && Variables.audioOn)
{
AudioManager.Instance.playPowerDown();
}
powerDownSnake();
}
noKeyPressed = true;
bool allowTail = true;
bool allowHead = true;
bool shrinkMode = false;
if (kstate.IsKeyDown(Keys.LeftShift))
{
shrinkMode = true;
noKeyPressed = false;
}
else if (kstate.IsKeyDown(Keys.W) || kstate.IsKeyDown(Keys.S) || kstate.IsKeyDown(Keys.A) || kstate.IsKeyDown(Keys.D))
{
tailMoving = false;
noKeyPressed = false;
}
if (noKeyPressed == true)
{
return;
}
if (positions.Count == Variables.maxLength)
{
allowHead = false;
allowTail = false;
}
//if player is holding shift, shrink a node every n frames
if (shrinkMode)
{
if (framesPassedTail < Variables.shrinkEveryNFrames)
{
framesPassedTail++;
return;
}
else
{
framesPassedTail = 0;
shrinkSnake(1, direction);
if (Variables.audioOn && Variables.fxOn)
{
AudioManager.Instance.shrink.Play();
}
return;
}
}
//dont change any positions if the snake isnt moving
if (!noKeyPressed)
{
if ((tailMoving && allowTail) || (!tailMoving && allowHead))
{
//are we moving the head or the tail now?
var head = positions[0];
var lastPreviousPosition = head;
var lastPreviousDirection = direction;
//move head or tail first
if (!tailMoving)
{
//apply movement
if (kstate.IsKeyDown(Keys.W))
{
head.Y -= snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
direction = GraphicsManager.Direction.up;
noKeyPressed = false;
}
else if (kstate.IsKeyDown(Keys.S))
{
head.Y += snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
direction = GraphicsManager.Direction.down;
noKeyPressed = false;
}
else if (kstate.IsKeyDown(Keys.A))
{
head.X -= snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
direction = GraphicsManager.Direction.left;
}
else if (kstate.IsKeyDown(Keys.D))
{
head.X += snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
direction = GraphicsManager.Direction.right;
noKeyPressed = false;
}
}
//record the head's movement
previousPositions.Insert(0, lastPreviousPosition);
previousDirections.Insert(0, lastPreviousDirection);
//this stops the snake from moving out of the screen :)
head.X = Math.Min(Math.Max(GraphicsManager.Instance.headUp.Width / 2, head.X), graphics.PreferredBackBufferWidth - GraphicsManager.Instance.headUp.Width / 2);
head.Y = Math.Min(Math.Max(GraphicsManager.Instance.headUp.Height / 2, head.Y), graphics.PreferredBackBufferHeight - GraphicsManager.Instance.headUp.Height / 2);
//check collision, if this move is allowed, store the position - if not, stay where we are!
//now that we dont use obstacles anymore this if statement is obsolete
if (doesIntersect)
{
snakeSpeed = snakeSpeed / Variables.slowdown;
Console.WriteLine("Speed: " + snakeSpeed);
if (direction == GraphicsManager.Direction.up)
{
head.Y += Variables.collisionModifier * snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
}
else if (direction == GraphicsManager.Direction.down)
{
head.Y -= Variables.collisionModifier * snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
}
else if (direction == GraphicsManager.Direction.left)
{
head.X += Variables.collisionModifier * snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
}
else if (direction == GraphicsManager.Direction.right)
{
head.X -= Variables.collisionModifier * snakeSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds;
}
}
//if the snake has slowed down, it gradually gets back to its max speed
if (snakeSpeed < Variables.maxSpeed)
{
snakeSpeed++;
}
//save the new head and direction variables
positions[0] = head;
directions[0] = direction;
////set the correct orientation asset
snakeBody[0] = GraphicsManager.Instance.getSnakeTexture(directions[0], GraphicsManager.SnakePart.head);
snakeBody[snakeBody.Count - 1] = GraphicsManager.Instance.getSnakeTexture(directions[directions.Count - 1], GraphicsManager.SnakePart.tail);
// loop through list, set positions for all nodes while incrementing positions
for (int i = 1; i < positions.Count; i++)
{
//set position
Vector2 temp = positions[i];
if (previousPositions.Count != 0 && previousPositions.Count > i * Variables.spacing)
{
temp = previousPositions.ToArray()[i * Variables.spacing];
}
//store back in list
positions[i] = temp;
//update texture
if (previousDirections.Count != 0 && previousDirections.Count > i * Variables.spacing)
{
if (i != positions.Count - 1)
{
snakeBody[i] = GraphicsManager.Instance.getSnakeTexture(previousDirections.ToArray()[i * Variables.spacing],
GraphicsManager.SnakePart.body);
}
else if (i == positions.Count - 1)
{
snakeBody[i] = GraphicsManager.Instance.getSnakeTexture(previousDirections.ToArray()[i * Variables.spacing],
GraphicsManager.SnakePart.tail);
}
directions[i] = previousDirections.ToArray()[i * Variables.spacing];
}
}
//if the snake is not at max length, add a new node every n frames
if (framesPassedHead < Variables.growEveryNFrames)
{
framesPassedHead++;
}
else
{
framesPassedHead = 0;
if (previousPositions.Count > Variables.spacing * positions.Count && positions.Count < Variables.maxLength)
{
Vector2 position = positions[positions.Count - 1];
growSnake(position);
snakeLength++;
if (Variables.audioOn && Variables.fxOn)
{
AudioManager.Instance.grow.Play();
}
}
}
}
//save the keyboard state so we can tell if keys can being held down etc
previousKB = kstate;
}
}
