We Keep Coding

C# MonoGame: Moving Sprite Image Up and Down Using Xbox 360 GamePad

Here is the code from my MonoGame project where I have one player image in the bottom left corner and another player image in the top right. The goal is to use the left thumbstick on an Xbox 360 controller to move the player 1 on the left up and down. I used a break point and found that my controller is connected, but nothing happens when I use the thumbstick. Here is my code:
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
namespace _2PersonShooterGame_v0._1
{
/// <summary>
/// This is the main type for your game.
/// </summary>
public class Game1 : Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
// GamePad support
const float THUMB_STICK_DEFELCTION = 100;
//Window Resolution support
const int WINDOW_WIDTH = 1200;
const int WINDOW_HEIGHT = 800;
// player images and their rectabgles support
Texture2D player1;
Rectangle drawRect1;
Texture2D player2;
Rectangle drawRect2;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
// Change resolution to 1200, 800
graphics.PreferredBackBufferWidth = WINDOW_WIDTH;
graphics.PreferredBackBufferHeight = WINDOW_HEIGHT;
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
// Load sprites
player1 = Content.Load<Texture2D>(#"graphics\sprite_player1");
player2 = Content.Load<Texture2D>(#"graphics\sprite_player2");
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// game-specific content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <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)
{
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
Exit();
// Move player1 up and down using the thumbstick on an Xbox 360 remote
GamePadState gamepad = GamePad.GetState(PlayerIndex.One);
if (gamepad.IsConnected)
{
drawRect1.Y -= (int)(gamepad.ThumbSticks.Left.Y * THUMB_STICK_DEFELCTION);
}
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
// Drawing sprites in their respective rectangles
spriteBatch.Begin();
// Place player one in the bottom left corner and player two in the top right corner
drawRect1 = new Rectangle(0, WINDOW_HEIGHT - player1.Height, player1.Width, player1.Height);
drawRect2 = new Rectangle(WINDOW_WIDTH - player2.Width, 0, player2.Width, player2.Height);
spriteBatch.Draw(player1, drawRect1, Color.White);
spriteBatch.Draw(player2, drawRect2, Color.White);
spriteBatch.End();
base.Draw(gameTime);
}
}
}

The problem is that you're setting drawRect1.Y property in the Update(...) method but then again you're overriding this rectangle in your Draw(...) method.
// update
if (gamepad.IsConnected)
{
drawRect1.Y -= (int)(gamepad.ThumbSticks.Left.Y * THUMB_STICK_DEFELCTION);
}
// draw
drawRect1 = new Rectangle(0, WINDOW_HEIGHT - player1.Height, player1.Width, player1.Height);
What you should do i to just update rectangle in your Update(...) method and use the same ( updated ) value in Draw(...) call.
To fix this just remove this line : drawRect1 = new Rectangle(0, WINDOW_HEIGHT - player1.Height, player1.Width, player1.Height); from your Draw(...) method.

C#, showing a variable on screen

The game that i am making using C# is Square Chase. You mouse over the block and click it before it moves. The timer will count down in the back ground and the score will be raised by 1 each "tag" on the block. You can do the Project on XNA 4.0 Game Development by Example. This is 2010 C# and The project type is Windows Game (4.0).
Now I want to add extra stuff to it. I want take away 5 seconds of time every time they click on the block, but I don't know if its working so I need to make the time remaining visible. I want to make it smaller every time you hit the square.
Code: (under update and the if statement I have already done the subtraction on the time but would want to make sure its working by making it visible) Thank You
I need to find out how to sink and in large an image, I need to know how to show a float on the screen.
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
namespace RFSquareChase
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Random rand = new Random ();
Texture2D squareTexture;
Rectangle currentSquare;
int playerScore = 0;
float timeRemaining = 0.0f;
const float TimePerSquare = 0.75f;
Color [] colors = new Color[3] { Color.Red, Color.Green, Color.Blue };
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
this.IsMouseVisible = true;
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
squareTexture = Content.Load<Texture2D>(#"SQUARE");
// TODO: use this.Content to load your game content here
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// all content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <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();
// TODO: Add your update logic here
if (timeRemaining == 0.0f)
{
currentSquare = new Rectangle(
rand.Next(0, this.Window.ClientBounds.Width - 25),
rand.Next(0, this.Window.ClientBounds.Height - 25),
25, 25);
timeRemaining = TimePerSquare;
}
MouseState mouse = Mouse.GetState();
if ((mouse.LeftButton == ButtonState.Pressed) &&
(currentSquare.Contains(mouse.X, mouse.Y)))
{
playerScore++;
timeRemaining = 0.0f;
timeRemaining = timeRemaining - 5;
}
timeRemaining = MathHelper.Max(0, timeRemaining - (float)gameTime.ElapsedGameTime.TotalSeconds);
this.Window.Title = "Score : " + playerScore.ToString();
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.Gray);
spriteBatch.Begin();
spriteBatch.Draw(
squareTexture,
currentSquare,
colors[playerScore % 3]);
spriteBatch.End();
// TODO: Add your drawing code here
base.Draw(gameTime);
}
}
}

To show a float on screen you simply use spriteBatch.DrawString, and could be useful Math.Round to show only the decimal you want. As you can see here.
To change the dimension of a sprite you can set the scale parameter in your spriteBatch.Draw. As you can see here

Game lagging (beginner)

I am creating a game in which asteroids spawn and move down the screen. In the update method of the game, i am using a random number to spawn the asteroids sporatically. When i start it up, it begins to lag within the first 5 seconds. I can see this because the score counter(which goes up every tick) starts going in intervals of 30. Also, the images of the asteroid do not even show up.
Here is the gameObject class:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;
namespace thedodger
{
public abstract class gameObject
{
public static Texture2D texture;
public Rectangle rectangle;
public abstract void Draw(SpriteBatch spriteBatch);
public abstract void Update(GameTime gameTime);
}
}
here is the asteroid class;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;
namespace thedodger
{
public class Asteroid : gameObject
{
Random rand = new Random(1);
int yPos = -10;
public override void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Begin();
spriteBatch.Draw(texture, new Rectangle(rand.Next(32,400), yPos,32,32),Color.White);
spriteBatch.End();
}
public override void Update(GameTime gameTime)
{
yPos--;
}
}
}
and here is the game1 class:
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using Microsoft.Xna.Framework.Net;
using Microsoft.Xna.Framework.Storage;
namespace thedodger
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
int scorevalue = 0;
SpriteFont font;
player player1 = new player();
List<gameObject> objectList = new List<gameObject>();
Random rand = new Random(1);
Asteroid asteroid = new Asteroid();
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
font = Content.Load<SpriteFont>("font");
//player1.image = Content.Load<Texture2D>("EnemyShip005.png");
gameObject.texture = Content.Load<Texture2D>("asteroid");
// TODO: use this.Content to load your game content here
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// all content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <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)
{
scorevalue++;
if (rand.Next(0, 8) == 2)
{
for (int i = 0; i < 30; i++)
{
objectList.Add(asteroid);
}
}
foreach (Asteroid asteroid in objectList)
{
asteroid.Update(gameTime);
asteroid.Draw(spriteBatch);
}
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
// TODO: Add your update logic here
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
// TODO: Add your drawing code here
spriteBatch.Begin();
spriteBatch.DrawString(font, "Score: " + scorevalue, new Vector2(5, 5), Color.White);
spriteBatch.End();
base.Draw(gameTime);
}
}
}
All help would be greatly appreciated.
sorry about the code. I am having difficult setting it up. Help on that too please.

As Tobias said, you probably should have put this on the Game Dev site and you appear to only have one Asteroid instantiated. In the Game1 object, you declare and instantiate an Asteroid object. Then in the Update method you add it repeatedly to the objectList. To get what I think you want, you should change
Asteroid asteroid = new Asteroid();
to
Asteroid asteroid;
Then change
for (int i = 0; i < 30; i++)
{
objectList.Add(asteroid);
}
to
for (int i = 0; i < 30; i++)
{
asteroid = new Asteroid();
objectList.Add(asteroid);
}
In your original code you declare and instantiate asteroid as a specific Asteroid but then never change it. So, throughout the whole program asteroid is pointed to one specific instance of an Asteroid. Then you repeatedly add asteroid to the objectList. So after each frame, 30 new references to the same asteroid object are being added to the objectList and the Update() and Draw() methods are being called on asteroid for every reference to it in objectList. So after 30 frames, one second if running at 30FPS, up to 900 references to the same exact asteroid object are in objectList and on that 30th frame asteroid is having its Update() and Draw() methods called up to 900 times. I'm pretty sure this is the source of your lag. Doing the corrections given above will result in objectList being populated with up to 900 different Asteroids, but will certainly experience lag as well. What you need to do as well is add a limit to the amount of asteroids on screen at any given time (the length of objectList can only be x amount) and/or lower the amount of asteroids created each time. I would suggest something like
for (int i = 0; i < 5; i++)
{
if (objectList.Count < 50) // Maximum asteroids on screen
{
asteroid = new Asteroid();
objectList.Add(asteroid);
}
}
will result in only five new asteroids for time and a maximum of 50 at any given time. If you add in functionality to destroy asteroids though, you'll have to remember to remove them from the objectList.
EDIT- As Neomex has said, your drawing is also a problem. I would suggest checking out the GDC 2008 talk on the XNA Framework performance here: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=6082
It very briefly covers some drawing and calculation performances and what you should/shouldn't do.
EDIT2- Actually, because of your random probability, it would be up to 900 object references and calls, not a full 900.

Try to make as least begin-end calls as possible, they often slow down game a lot.
( Asteroid class )
You are displaying graphics in your update function which is really bad thing.
If these fail, try to download newest drivers.
Reasuming:
Change in your asteroid class
public override void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Begin();
spriteBatch.Draw(texture, new Rectangle(rand.Next(32,400), yPos,32,32),Color.White);
spriteBatch.End();
}
to
public override void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, new Rectangle(rand.Next(32,400), yPos,32,32),Color.White);
}
Now in your update function
foreach (Asteroid asteroid in objectList)
{
asteroid.Update(gameTime);
asteroid.Draw(spriteBatch);
}
to
foreach (Asteroid asteroid in objectList)
{
asteroid.Update(gameTime);
}
And add this in draw function:
foreach (Asteroid asteroid in objectList)
{
asteroid.Draw(spriteBatch);
}

As Tobias has already pointed out, you are using the same asteriod object every time you want to spawn a new asteriod. You need to do add a new Asteriod() to the object list instead of using the same one.
Also, this code is mostly likely the reason you are suffering performance wise.
if (rand.Next(0, 8) == 2)
{
for (int i = 0; i < 30; i++)
{
objectList.Add(asteroid);
}
}
You are adding 30 instances of the same object to the collection on every update call (with is around 60 times a second). I realize you are using a random number, but it sill happens to about 12.5% of the update calls.
So within a 5-10 seconds, you now have thousands of these objects and are drawing the same image thousands and thousands of times.

"nullreferenceexception was unhandled" in body.cs of farseer physics engine

I'm a c++ programmer trying out c#. I've done a lot with box2d in c++, but this is my first time with c#. So, I'm trying to make a simple game with farseer physics engine. When I try to compile my code (I'm using visual studio c# 2010 express and xna game studio 4.0), it stops in body.cs at IBroadPhase broadPhase = World.ContactManager.BroadPhase; With this error: nullreferenceexception was unhandled. I believe the problem is in my Player class, so here's the code for that:
public class Player : Entity
{
Vector2 position;
SpriteBatch spriteBatch;
Texture2D texture;
Rectangle rectangle;
Body body;
CircleShape shape;
Fixture fixture;
public Player()
{
// TODO: Construct any child components here
}
///
/// Allows the game component to perform any initialization it needs to before starting
/// to run. This is where it can query for any required services and load content.
///
public override void Initialize(World world, SpriteBatch spriteBatch, Texture2D texture)
{
// TODO: Add your initialization code here
this.spriteBatch = spriteBatch;
this.texture = texture;
rectangle = new Rectangle(0, 0, 11, 14);
body = BodyFactory.CreateBody(world);
body.BodyType = BodyType.Dynamic;
body.Position = new Vector2(0, 0);
shape = new CircleShape(1.0f, 1.0f);
fixture = body.CreateFixture(shape);
base.Initialize(world, spriteBatch, texture);
}
///
/// Allows the game component to update itself.
///
/// <param name="gameTime" />Provides a snapshot of timing values.
public override void Update(GameTime gameTime)
{
// TODO: Add your update code here
base.Update(gameTime);
}
public override void Draw(GameTime gameTime)
{
spriteBatch.Begin();
spriteBatch.Draw(texture, new Vector2(body.WorldCenter.X * 10, body.WorldCenter.Y * 10), rectangle, Color.White);
spriteBatch.End();
base.Draw(gameTime);
}
}
The farseer testbed runs fine, so I'm pretty sure my code is the problem, and not farseer. Let me know if you need to see more of my code. I've also posted this in the farseer forums, so If I get an answer there, I'll let you guys know. Thanks in advance.

Someone asked me to show the code of Game1.cs, and found the problem. The problem was that I had never constructed the world before initializing my player. It was fixed by adding world = new World(Vector2.Zero); before I initialized the player.

Lining up sprites with scale and rotation around arbitrary point

I have 2 sprites which when drawn together make up the correct image on the screen. Drawing them both at the same time is not an option.
Imagine this class:
class MyImage
{
Vector2 drawOffset; // this gets added before the image is drawn
Vector2 sourceRect; // this is where it is on the source texturepage
void Draw(Vector2 position)
{
position = position + drawOffset;
spriteBatch.Draw(sourceTexture, position, sourceRect, Color.White);
}
}
And this code calling into it:
MyImage a = new MyImage(); // assume they get initialised correctly
MyImage b = new MyImage(); // with different drawOffsets and sourceRects
a.Draw(position); // this composes the final
b.Draw(position); // screen image from the 2 source images
Now I'd like to add scale and rotation to the Draw() function, but am having real trouble getting the parameters to the SpriteBatch.Draw function correct. This would be the version which takes scale, rotation and an origin. I need the final composed image to scale and rotate correctly (around some arbitrary centre) but can't for the life of me work out how to manipulate the scale, rotation and origin parameters to make the 2 images appear to scale and rotate in concert. Has anyone done something like this before? Happy to mod the question based on feedback if anything's unclear. If images would help I can get them posted somewhere...
I've looked at rotation around point xna 2D but am still stumped.
Cheers,
Charlie.
Thanks so much for the answer below - using it I've managed to get the images rendering correctly. One other issue remains, which is that I seem to need to use a lot of spritebatch.Begin/End pairs (one per image render). I don't have a way to measure performance on this device yet and the framerate's not chugging so I guess it's not a problem.
Here's my code:
// gr is the graphic object:
// gr.position is the location of the image in the atlas
// gr.DrawOffset is the draw offset so the image is placed correctly in it's virtual box
// gr.pageIndex is the index into the texture/atlas array
// hw,hh are half the width/height of the image (it always rotates around it's centre in fact)
Matrix m = Matrix.CreateTranslation(-hw, -hh, 0) *
Matrix.CreateRotationZ(rotation) * // rotation : parameter
Matrix.CreateScale(scale) * // scale : parameter
Matrix.CreateTranslation(pos.X + hw, pos.Y + hh, 0); // pos : parameter!
spriteBatch.Begin(SpriteSortMode.Deferred, null, null, null, null, null, m);
spriteBatch.Draw(page[gr.pageIndex].texture, gr.DrawOffset, gr.position, color);
spriteBatch.End();

If you are going to work with the SpriteBatch.Draw to draw the textures I would suggest that you forgo trying to manipulate the origin, scale arguments to try an achieve this, simply I doubt it can be done this way. But you do have an alternative, you can manipulate the SpriteBatch Matrix.
Here is a quick and dirty example, note that the texture I used here is 128x96 so I hard coded the values for that image size. Do not look for any best practices in this code, I wrote it to try and show the concept as cleanly as possible.
using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
namespace WindowsGame1
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
private Texture2D _texture;
private MyImage _image1;
private MyImage _image2;
// Attributes of the composed sprite
private float _angle = 0.0f;
private Vector2 _position = new Vector2(100, 100);
private Vector2 _rotationPoint = new Vector2(96, 48);
public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}
/// <summary>
/// Allows the game to perform any initialization it needs to before starting to run.
/// This is where it can query for any required services and load any non-graphic
/// related content. Calling base.Initialize will enumerate through any components
/// and initialize them as well.
/// </summary>
protected override void Initialize()
{
// TODO: Add your initialization logic here
base.Initialize();
}
/// <summary>
/// LoadContent will be called once per game and is the place to load
/// all of your content.
/// </summary>
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
_texture = Content.Load<Texture2D>("Gravitar");
// Create the two MyImage instances
_image1 = new MyImage(_texture, Vector2.Zero, Vector2.Zero);
_image2 = new MyImage(_texture, new Vector2(64, 0), new Vector2(64, 0));
}
/// <summary>
/// UnloadContent will be called once per game and is the place to unload
/// all content.
/// </summary>
protected override void UnloadContent()
{
// TODO: Unload any non ContentManager content here
}
/// <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();
float elapsedTime = (float)gameTime.ElapsedGameTime.TotalSeconds;
_angle += 0.5f * elapsedTime;
if (Mouse.GetState().LeftButton == ButtonState.Pressed)
{
_angle = 0.0f;
}
if (Keyboard.GetState().IsKeyDown(Keys.Left))
_position += new Vector2(-10, 0)*elapsedTime;
if (Keyboard.GetState().IsKeyDown(Keys.Right))
_position += new Vector2(10, 0) * elapsedTime;
base.Update(gameTime);
}
/// <summary>
/// This is called when the game should draw itself.
/// </summary>
/// <param name="gameTime">Provides a snapshot of timing values.</param>
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.CornflowerBlue);
// Setup the sprite batch matrix
// Notice that we first translate to the point or rotation
// then rotate and when we translate to the desired position we
// need to compensate for the first translation so that the texture
// appears at the correct location
Matrix m =
Matrix.CreateScale(1.5f)
* Matrix.CreateTranslation(-_rotationPoint.X, -_rotationPoint.Y, 0)
* Matrix.CreateRotationZ(_angle)
* Matrix.CreateTranslation(_position.X + _rotationPoint.X, _position.Y + _rotationPoint.Y, 0);
// Begin the SpriteBatch passing the matrix
spriteBatch.Begin(SpriteSortMode.Deferred, null, null, null, null, null, m);
_image1.Draw(spriteBatch);
_image2.Draw(spriteBatch);
spriteBatch.End();
base.Draw(gameTime);
}
class MyImage
{
Vector2 _drawOffset;
Vector2 _sourcePoint;
Texture2D _sourceTexture;
public MyImage(Texture2D sourceTexture, Vector2 sourcePoint, Vector2 drawOffset)
{
_drawOffset = drawOffset;
_sourcePoint = sourcePoint;
_sourceTexture = sourceTexture;
}
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(_sourceTexture, _drawOffset,
new Rectangle((int)_sourcePoint.X, (int)_sourcePoint.Y, 64, 96),
Color.White);
}
}
}
}