Question

I have created 3 classes: one for the game, one for the model and one for the camera. I want my camera to follow my model as it moves, but my model is no longer appearing. Does anyone have any idea what I’m doing wrong in my camera and/or game 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;

namespace test1
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;



    //Visual components
    Ship ship = new Ship();
    Cam cam1 = new Cam();        




    public Game1()
    {
        graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
    }      

    protected override void LoadContent()
    {
        ship.Model = Content.Load<Model>("Models/p1_wedge");
        ship.Transforms = cam1.SetupEffectDefaults(ship.Model);            
    }

    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();

        // Get some input.
        UpdateInput();

        // Add velocity to the current position.
        ship.Position += ship.Velocity;
        cam1.cameraPosition += cam1.cameraTarget;
        // Bleed off velocity over time.
        ship.Velocity *= 0.95f;
        cam1.cameraTarget *= 0.95f;

        base.Update(gameTime);
    }

    protected void UpdateInput()
    {
        // Get the game pad state.
        GamePadState currentState = GamePad.GetState(PlayerIndex.One);
        KeyboardState currentKeyState = Keyboard.GetState();

            ship.Update(currentState);
            cam1.Update(currentState);

            // In case you get lost, press A to warp back to the center.
            if (currentState.Buttons.A == ButtonState.Pressed || currentKeyState.IsKeyDown(Keys.Enter))
            {
                ship.Position = Vector3.Zero;
                ship.Velocity = Vector3.Zero;
                ship.Rotation = 0.0f;                  
            }            
    }

    protected override void Draw(GameTime gameTime)
    {
        graphics.GraphicsDevice.Clear(Color.CornflowerBlue);

        Matrix shipTransformMatrix = ship.RotationMatrix
                * Matrix.CreateTranslation(ship.Position);
        DrawModel(ship.Model, shipTransformMatrix, ship.Transforms);
        base.Draw(gameTime);
    }


    public static void DrawModel(Model model, Matrix modelTransform,
Matrix[] absoluteBoneTransforms)
    {
        //Draw the model, a model can have multiple meshes, so loop
        foreach (ModelMesh mesh in model.Meshes)
        {
            //This is where the mesh orientation is set
            foreach (BasicEffect effect in mesh.Effects)
            {
                effect.World =
                    absoluteBoneTransforms[mesh.ParentBone.Index] *
                    modelTransform;
            }
            //Draw the mesh, will use the effects set above.
            mesh.Draw();
        }
    }
}
}

---

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;


namespace test1
{
class Ship
{
    public Model Model;
    public Matrix[] Transforms;

    //Position of the model in world space
    public Vector3 Position = Vector3.Zero;

    //Velocity of the model, applied each frame to the model's position
    public Vector3 Velocity = Vector3.Zero;
    private const float VelocityScale = 5.0f;

    public Matrix RotationMatrix =
 Matrix.CreateRotationX(MathHelper.PiOver2);

    private float rotation;

    public float Rotation
    {
        get { return rotation; }
        set
        {
            float newVal = value;
            while (newVal >= MathHelper.TwoPi)
            {
                newVal -= MathHelper.TwoPi;
            }
            while (newVal < 0)
            {
                newVal += MathHelper.TwoPi;
            }

            if (rotation != value)
            {
                rotation = value;
                RotationMatrix =
                    Matrix.CreateRotationX(MathHelper.PiOver2) *
                    Matrix.CreateRotationZ(rotation);
            }

        }
    }

    public void Update(GamePadState controllerState)
    {

        KeyboardState currentKeyState = Keyboard.GetState();
        if (currentKeyState.IsKeyDown(Keys.A))
            Rotation += 0.10f;
        else
        // Rotate the model using the left thumbstick, and scale it down.
        Rotation -= controllerState.ThumbSticks.Left.X * 0.10f;

        if (currentKeyState.IsKeyDown(Keys.D))
            Rotation -= 0.10f;

        if (currentKeyState.IsKeyDown(Keys.W))
            Velocity += RotationMatrix.Forward * VelocityScale;
        else
        // Finally, add this vector to our velocity.
        Velocity += RotationMatrix.Forward * VelocityScale *
         controllerState.Triggers.Right;
    }  

}
}

---

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;


namespace test1
{
class Cam : Microsoft.Xna.Framework.Game
{
    public Vector3 cameraPosition = new Vector3(0.0f, 2000.0f, 25000.0f);
    public Vector3 cameraTarget = Vector3.Zero;

   Matrix projectionMatrix;
    Matrix viewMatrix;

    protected override void Initialize(){

            projectionMatrix = Matrix.CreatePerspectiveFieldOfView(
       MathHelper.ToRadians(45.0f),
       GraphicsDevice.DisplayMode.AspectRatio,
       20000.0f, 30000.0f);

        viewMatrix = Matrix.CreateLookAt(cameraPosition,
            cameraTarget, Vector3.Up);

        base.Initialize();            
    }

    public Matrix[] SetupEffectDefaults(Model myModel)
    {
        Matrix[] absoluteTransforms = new Matrix[myModel.Bones.Count];
        myModel.CopyAbsoluteBoneTransformsTo(absoluteTransforms);

        foreach (ModelMesh mesh in myModel.Meshes)
        {
            foreach (BasicEffect effect in mesh.Effects)
            {
                effect.EnableDefaultLighting();
                effect.Projection = projectionMatrix;
                effect.View = viewMatrix;
            }
        }
        return absoluteTransforms;
    }

    private const float VelocityScale = 5.0f;

    public Matrix RotationMatrix =
 Matrix.CreateRotationX(MathHelper.PiOver2);

    private float rotation;

    public float Rotation
    {
        get { return rotation; }
        set
        {
            float newVal = value;
            while (newVal >= MathHelper.TwoPi)
            {
                newVal -= MathHelper.TwoPi;
            }
            while (newVal < 0)
            {
                newVal += MathHelper.TwoPi;
            }

            if (rotation != value)
            {
                rotation = value;
                RotationMatrix =
                    Matrix.CreateRotationX(MathHelper.PiOver2) *
                    Matrix.CreateRotationZ(rotation);
            }
        }
    }

    public void Update(GamePadState controllerState)
    {
        KeyboardState currentKeyState = Keyboard.GetState();
        if (currentKeyState.IsKeyDown(Keys.A))
            Rotation += 0.10f;
        else
            // Rotate the model using the left thumbstick, and scale it down.
            Rotation -= controllerState.ThumbSticks.Left.X * 0.10f;

        if (currentKeyState.IsKeyDown(Keys.D))
            Rotation -= 0.10f;

        if (currentKeyState.IsKeyDown(Keys.W))
            cameraTarget += RotationMatrix.Forward * VelocityScale;
        else
            // Finally, add this vector to our velocity.
            cameraTarget += RotationMatrix.Forward * VelocityScale *
             controllerState.Triggers.Right;
    }
}
}

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Answer 1

First, you should learn how to organize your code, you created classes for each object but you still do some of the processing in each object and some in game, this is very messy!

The short answer to why your camera is not working, is simply because you are not using it!

You should follow a proper tutorial on creating a camera in XNA, like this one, but from looking briefly at your code, adding something like cam1.SetupEffectDefaults(model); in your DrawModel might be sufficient to have your ViewMatrix and ProjectionMatrix applied. Calling it in the init phase won’t do much, as these matrices are updated during the game.