A view and projection matrix oddity?

Question

I have a bit of a dilemma ... So i setup my scene how I want it with some bits in it and now I want to move all my camera related code in to a camera class however doing so is proving to be a pain in my ass.

So in my game code (my main game class) I have ...

    protected override void Initialize()
    {
        model = new TerrainModel();
        base.Initialize();

        // Load known core components
        camera = new Camera(this, cameraPosition, new Vector3(10, 10, 10));
    }

Then in update ...

    protected override void Update(GameTime gameTime)
    {
        // Allows the game to exit
        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
            this.Exit();

        camera.Update();

        base.Update(gameTime);
    }

Then in draw ...

    protected override void Draw(GameTime gameTime)
    {
        cubeEffect.View = Matrix.CreateLookAt(cameraPosition, new Vector3(10, 10, 10), Vector3.Up);
        cubeEffect.View = camera.View;

        cubeEffect.Projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, aspectRatio, 1.0f, 1000.0f);
        cubeEffect.Projection = camera.Projection;
    }

It's these draw lines that have me confused. If i use the first pair (the lines that create the matrices there and then) it all works.

If I use the second pair (pulling the same thing from my camera class) it doesn't and i get a blank screen.

I'm only rendering a single model so there's a chance it could be pointing in the wrong direction but it seems to have done what i expect when i put breakpoints in and look at the variables.

So what have i done wrong?

Here's my camera class ...

public class Camera
{
    #region fields

    Matrix viewMatrix;
    Matrix projectionMatrix;
    Viewport viewPort;
    BoundingFrustum cameraViewableBounds;
    Vector3 currentTarget;
    Vector3 cameraPosition;

    #endregion

    #region Properties

    public Matrix Projection { get { return projectionMatrix; } }
    public Matrix View { get { return viewMatrix; } }
    public Viewport ViewPort { get { return viewPort; } }

    public Vector3 Position
    {
        get { return cameraPosition; }
        set
        {
            cameraPosition = value;
            Update();
        }
    }

    public Vector3 TargetPosition { get { return currentTarget; } }

    public bool CanSee(BoundingBox ObjectBounds)
    {
        if (cameraViewableBounds.Contains(ObjectBounds) != ContainmentType.Disjoint)
            return true;

        return false;
    }

    #endregion

    public Camera(Game game, Vector3 startingPosition, Vector3 startingTarget)
    {
        cameraPosition = startingPosition;

        // creates a new view matrix
        LookAt(startingTarget);

        viewPort = game.GraphicsDevice.Viewport;

        // Set the Projection matrix which defines how we see the scene (Field of view)
        projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, 0, 1, 10000);
    }

    #region Camera state updating

    public void Update()
    {
        viewMatrix = Matrix.CreateLookAt(cameraPosition, TargetPosition, Vector3.Up);
        cameraViewableBounds = new BoundingFrustum(viewMatrix * projectionMatrix);
    }

    public void LookAt(Vector3 target)
    {
        currentTarget = target;
        viewMatrix = Matrix.CreateLookAt(Position, TargetPosition, Vector3.Up);
    }

    #endregion
}

}

I'm sure this is something crazy simple that i've missed ... i just can't see it.

NOTE: I have omitted a lot of code here to try and simplify my question but I'm pretty sure the rest of my code is fine because it works unless I use this new camera class, however I can provide more if its needed.

Answer 1

Have a look at this line in the Camera class again:

projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, 0, 1, 10000);

You have your aspect ratio as zero (which won't work)

For what it's worth I think the call to LookAt is redundant/confusing in the Camera constructor -- if anything in the scene is going to ever move you will be needing to recreate the View matrix on Update anyway.

Last thing, have you heard of Auto Implemented properties?