/// <summary>
/// Allows the game to run logic such as updating the world,
/// checking for collisions, gathering input, and playing audio.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Update(GameTime gameTime)
{
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) {
this.Exit();
}
SnakeDirection oldDirection = snakeDirection;
Vector2 oldSnakePosition = snakePosition;
bool justInitialized = false;
// Get keyboard input
KeyboardState state = Keyboard.GetState();
if (IsKeyReleased(Keys.Space, state)) {
TogglePaused();
}
if (IsKeyReleased(Keys.R, state)) {
InitializeSnake();
justInitialized = true;
}
if (!paused && !justInitialized) {
if (state.IsKeyDown(Keys.Left)) {
if (snakeDirection != SnakeDirection.Right) {
snakeDirection = SnakeDirection.Left;
}
}
if (state.IsKeyDown(Keys.Right)) {
if (snakeDirection != SnakeDirection.Left) {
snakeDirection = SnakeDirection.Right;
}
}
if (state.IsKeyDown(Keys.Up)) {
if (snakeDirection != SnakeDirection.Down) {
snakeDirection = SnakeDirection.Up;
}
}
if (state.IsKeyDown(Keys.Down)) {
if (snakeDirection != SnakeDirection.Up) {
snakeDirection = SnakeDirection.Down;
}
}
}
if (IsKeyReleased(Keys.G, state)) {
GrowSnake();
}
if (state.IsKeyDown(Keys.OemPlus)) {
snakeSpeed += 5;
}
if (state.IsKeyDown(Keys.OemMinus)) {
snakeSpeed -= 5;
if (snakeSpeed < 0) {
snakeSpeed = 0;
}
}
if (state.IsKeyDown(Keys.OemCloseBrackets)) {
snakeLength += 1.0f;
}
if (state.IsKeyDown(Keys.OemOpenBrackets)) {
snakeLength -= 1.0f;
if (snakeLength < initialSnakeLength) {
snakeLength = initialSnakeLength;
}
}
if (state.IsKeyDown(Keys.W)) {
cameraPitch += 1.0f;
if (cameraPitch > 360.0f) {
cameraPitch -= 360.0f;
}
UpdateViewMatrix();
}
if (state.IsKeyDown(Keys.S)) {
cameraPitch -= 1.0f;
if (cameraPitch < 0) {
cameraPitch += 360.0f;
}
UpdateViewMatrix();
}
if (state.IsKeyDown(Keys.D)) {
cameraDistance += 1.0f;
UpdateViewMatrix();
}
if (state.IsKeyDown(Keys.A)) {
cameraDistance -= 1.0f;
if (cameraDistance < 0) {
cameraDistance = 0;
}
UpdateViewMatrix();
}
if (IsKeyReleased(Keys.V, state)) {
if (cameraType == CameraType.FromAbove) {
SetCameraType(CameraType.Angled);
} else {
SetCameraType(CameraType.FromAbove);
}
}
if (IsKeyReleased(Keys.T, state)) {
Toggle2DSnake();
}
if (IsKeyReleased(Keys.I, state)) {
ToggleOverlay();
}
if (IsKeyReleased(Keys.C, state)) {
ToggleIgnoreCollisions();
}
if (IsKeyReleased(Keys.B, state)) {
if (arenaBoundaryType == ArenaBoundaryType.WrapAround) {
arenaBoundaryType = ArenaBoundaryType.Collision;
} else if (arenaBoundaryType == ArenaBoundaryType.Collision) {
arenaBoundaryType = ArenaBoundaryType.NoBoundary;
} else {
arenaBoundaryType = ArenaBoundaryType.WrapAround;
}
}
if (state.IsKeyDown(Keys.Q) || state.IsKeyDown(Keys.Escape)) {
Exit();
}
oldKeyboardState = state;
if (!paused && !justInitialized) {
// Check if snake switched direction
if (snakeDirection != oldDirection) {
// Add position to list of joints
snakePositions.Add(new Vector2(oldSnakePosition.X, oldSnakePosition.Y));
disconnectedToPreviousPoint.Add(false);
}
// Move the snake
float displacement = (float)gameTime.ElapsedGameTime.TotalSeconds * snakeSpeed;
switch (snakeDirection) {
case SnakeDirection.Up:
snakePosition.Y -= displacement;
break;
case SnakeDirection.Down:
snakePosition.Y += displacement;
break;
case SnakeDirection.Left:
snakePosition.X -= displacement;
break;
case SnakeDirection.Right:
snakePosition.X += displacement;
break;
}
bool hit = false;
// Check if snake went out of bounds
if (arenaBoundaryType == ArenaBoundaryType.Collision) {
if (snakePosition.X < 0 ||
snakePosition.X > graphics.GraphicsDevice.Viewport.Width - 1 ||
snakePosition.Y < 0 ||
snakePosition.Y > graphics.GraphicsDevice.Viewport.Height - 1) {
hit = true;
}
} else if (arenaBoundaryType == ArenaBoundaryType.WrapAround) {
if (snakePosition.X < 0) {
oldSnakePosition = new Vector2(graphics.GraphicsDevice.Viewport.Width, snakePosition.Y);
snakePositions.Add(new Vector2(0, snakePosition.Y));
disconnectedToPreviousPoint.Add(false);
snakePositions.Add(oldSnakePosition);
disconnectedToPreviousPoint.Add(true);
snakePosition = new Vector2(graphics.GraphicsDevice.Viewport.Width + snakePosition.X, snakePosition.Y);
} else if (snakePosition.X > graphics.GraphicsDevice.Viewport.Width) {
oldSnakePosition = new Vector2(0, snakePosition.Y);
snakePositions.Add(new Vector2(graphics.GraphicsDevice.Viewport.Width, snakePosition.Y));
disconnectedToPreviousPoint.Add(false);
snakePositions.Add(oldSnakePosition);
disconnectedToPreviousPoint.Add(true);
snakePosition = new Vector2(snakePosition.X - graphics.GraphicsDevice.Viewport.Width, snakePosition.Y);
} else if (snakePosition.Y < 0) {
oldSnakePosition = new Vector2(snakePosition.X, graphics.GraphicsDevice.Viewport.Height);
snakePositions.Add(new Vector2(snakePosition.X, 0));
disconnectedToPreviousPoint.Add(false);
snakePositions.Add(oldSnakePosition);
disconnectedToPreviousPoint.Add(true);
snakePosition = new Vector2(snakePosition.X, graphics.GraphicsDevice.Viewport.Height + snakePosition.Y);
} else if (snakePosition.Y > graphics.GraphicsDevice.Viewport.Height) {
oldSnakePosition = new Vector2(snakePosition.X, 0);
snakePositions.Add(new Vector2(snakePosition.X, graphics.GraphicsDevice.Viewport.Height));
disconnectedToPreviousPoint.Add(false);
snakePositions.Add(oldSnakePosition);
disconnectedToPreviousPoint.Add(true);
snakePosition = new Vector2(snakePosition.X, snakePosition.Y - graphics.GraphicsDevice.Viewport.Height);
}
}
// Trim the snake tail, making sure the length of the snake is correct.
// Go backwards from current point through each point, adding up the displacement.
// Stop when you reach the right length, removing history of non relevant points.
float length = 0;
Vector2 lastPosition = snakePosition;
Vector2 vector = new Vector2();
int i;
for (i = snakePositions.Count - 1; i >= 0 && length <= snakeLength; --i) {
Vector2 position = snakePositions[i];
if (i == snakePositions.Count - 1 || !disconnectedToPreviousPoint[i + 1]) {
vector = lastPosition - position;
length += vector.Length();
}
lastPosition = position;
}
if (length > snakeLength) {
// Modify the tail end position
float changeAmount = length - snakeLength;
vector.Normalize();
vector = vector * changeAmount;
Vector2 newPosition = snakePositions[i + 1] + vector;
snakePositions[i + 1] = newPosition;
}
if (i >= 0) {
snakePositions.RemoveRange(0, i + 1);
disconnectedToPreviousPoint.RemoveRange(0, i + 1);
// Make sure the first element (the tail end point) is set to false
disconnectedToPreviousPoint[0] = false;
}
// Check if snake intersected with itself
LineSegment2 recentMovement = new LineSegment2(oldSnakePosition, snakePosition);
if (!hit && !ignoreSnakeCollisions) {
if (snakePositions.Count > 1) {
lastPosition = snakePositions[snakePositions.Count - 2];
i = snakePositions.Count - 3;
for (; i >= 0 && !hit; --i) {
Vector2 position = snakePositions[i];
LineSegment2 snakeSegment = new LineSegment2(position, lastPosition);
if (!disconnectedToPreviousPoint[i + 1]) {
hit = LineSegment2.SegmentsIntersect(recentMovement, snakeSegment);
}
lastPosition = position;
}
}
}
if (hit) {
InitializeSnake();
} else {
// Check if snake reached a goal
if (LineSegment2.SegmentsIntersect(recentMovement, goalLeftSide) ||
LineSegment2.SegmentsIntersect(recentMovement, goalRightSide) ||
LineSegment2.SegmentsIntersect(recentMovement, goalBottomSide) ||
LineSegment2.SegmentsIntersect(recentMovement, goalLeftSide)) {
// intersection
GrowSnake();
RepositionGoal();
}
Update3DSnakeData();
}
}
base.Update(gameTime);
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Set up the arena
arenaVertices = new VertexPositionNormalTexture[4];
arenaVertices[0] = new VertexPositionNormalTexture(new Vector3(0, 0, graphics.GraphicsDevice.Viewport.Height),
new Vector3(0, 1, 0),
new Vector2(0, 0));
arenaVertices[1] = new VertexPositionNormalTexture(new Vector3(0, 0, 0),
new Vector3(0, 1, 0),
new Vector2(0, 0));
arenaVertices[2] = new VertexPositionNormalTexture(new Vector3(graphics.GraphicsDevice.Viewport.Width, 0, 0),
new Vector3(0, 1, 0),
new Vector2(0, 0));
arenaVertices[3] = new VertexPositionNormalTexture(new Vector3(graphics.GraphicsDevice.Viewport.Width, 0,
graphics.GraphicsDevice.Viewport.Height),
new Vector3(0, 1, 0),
new Vector2(0, 0));
arenaVertexBuffer = new VertexBuffer(graphics.GraphicsDevice, typeof(VertexPositionNormalTexture),
arenaVertices.Length, BufferUsage.None);
arenaVertexBuffer.SetData<VertexPositionNormalTexture>(arenaVertices);
arenaIndexBuffer = new IndexBuffer(graphics.GraphicsDevice, typeof(int), arenaIndices.Length, BufferUsage.None);
arenaIndexBuffer.SetData<int>(arenaIndices);
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
// Load the basic white texture for snake and goal
blockTexture = new Texture2D(GraphicsDevice, (int)blockSize.X, (int)blockSize.Y, false, SurfaceFormat.Color);
Int32[] pixels = new Int32[blockTexture.Width * blockTexture.Height];
for (int i = 0; i < blockTexture.Width * blockTexture.Height; ++i) {
pixels[i] = 0xFFFFFF;
}
blockTexture.SetData<Int32>(pixels, 0, blockTexture.Width * blockTexture.Height);
overlayFont = Content.Load<SpriteFont>("OverlayFont");
fontPosition = new Vector2(5, 5);
snakeSpeed = defaultSnakeSpeed;
snakeGrowLength = defaultSnakeGrowLength;
fieldOfViewAngle = defaultFieldOfViewAngle;
show2DSnake = defaultShow2DSnake;
showOverlay = defaultShowOverlay;
ignoreSnakeCollisions = defaultIgnoreSnakeCollisions;
arenaBoundaryType = defaultArenaBoundaryType;
SetCameraType(defaultCameraType);
InitializeSnake();
}
