Question

I was just messing around with XNA and trying to get a simple player class that could move around through keyboard controls. I can’t seem to get it to draw the way I have it set up now though. I’m not seeing what error I’m making.

Here’s the Actor base class:

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace RunnerTEst
{
    class Actor
    {
        public static List<Actor> actors;

        public Texture2D texture;

        protected Vector2 position;
        protected float rotation;
        protected float scale;
        protected Color color;

    #region Constructors

        static Actor()
        {
            actors = new List<Actor>();
        }

        public Actor(Texture2D texture)
        {
            actors.Add(this);
            this.texture = texture;
            this.position = Vector2.Zero;
            this.rotation = 0f;
            this.scale = 1f;
        }

    #endregion

    #region Properties

        public Vector2 Position 
        {
            get { return this.position; }
            set { this.position = value; }
        }

        public Vector2 Origin
        {
            get { return new Vector2(this.position.X + this.texture.Width / 2,
                                     this.position.Y + this.texture.Height / 2); }
        }

        public float Rotation
        {
            get { return this.rotation; }
            set { this.rotation = value; }
        }

        public float Scale
        {
            get { return this.scale; }
            set { this.scale = value; }
        }

        public Color Color
        {
            get { return this.color; }
            set { this.color = value; }
        }

        public float Width
        {
            get { return this.texture.Width; }
        }

        public float Height
        {
            get { return this.texture.Height; }
        }

    #endregion

    #region Methods

        public virtual void Update(GameTime gameTime)
        {

        }

        public virtual void Draw(SpriteBatch spriteBatch)
        {
            spriteBatch.Draw(this.texture, this.position, this.color);
        }

    #endregion
    }
}

Player class:

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

namespace RunnerTEst
{
    class Player : Actor
{
    private const float speed = 5f;

    protected Vector2 velocity;

    private static KeyboardState currState, prevState;

    static Player()
    {
        currState = prevState = Keyboard.GetState();
    }

    public Player(Texture2D texture, Vector2 position)
        : base(texture)
    {
        this.position = position;
        this.velocity = Vector2.Zero;
    }

    public override void Update(GameTime gameTime)
    {
        this.HandleInput();

        this.position += this.velocity;

        foreach (Actor actor in Actor.actors)
        {
            if (this == actor)
                continue;
            this.CheckCollision(actor);
        }

        base.Update(gameTime);
    }

    public override void Draw(SpriteBatch spriteBatch)
    {
        base.Draw(spriteBatch);
    }

    public void CheckCollision(Actor actor)
    {
        //--left/right sides
        if (this.position.X + this.Width > actor.Position.X) //right of this hitting left actor
        {
            this.position.X = actor.Position.X - this.Width;
        }
        else if (this.position.X < (actor.Position.X + actor.Width))//left this hit right actor
        {
            this.position.X = actor.Position.X + actor.Width;
        }

        //--top/bottom
        if (this.position.Y + this.Height > actor.Position.Y) //this bottom hit actor top
        {
            this.position.Y = actor.Position.Y - this.Width;
        }
        else if (this.position.Y < (actor.Position.Y + actor.Height))//this top hit actor bottom
        {
            this.position.Y = actor.Position.Y + actor.Height;
        }

        //TODO: check screen bounds
    }

    public void HandleInput()
    {
        currState = Keyboard.GetState();

        if (currState.IsKeyDown(Keys.W))
        {
            this.velocity.Y = -speed;
        }
        else if (currState.IsKeyDown(Keys.S))
        {
            this.velocity.Y = speed;
        }
        else
        {
            this.velocity.Y = 0f;
        }

        if (currState.IsKeyDown(Keys.A))
        {
            this.velocity.X = -speed;
        }
        else if (currState.IsKeyDown(Keys.D))
        {
            this.velocity.X = speed;
        }
        else
        {
            this.velocity.X = 0f;
        }

        prevState = currState;
    }
}
}

and lastly, the game:

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 RunnerTEst
{
public class Game1 : Microsoft.Xna.Framework.Game
{
    GraphicsDeviceManager graphics;
    SpriteBatch spriteBatch;

    Texture2D playerTexture;
    Player me;

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

    protected override void Initialize()
    {


        base.Initialize();
    }

    protected override void LoadContent()
    {
        // Create a new SpriteBatch, which can be used to draw textures.
        spriteBatch = new SpriteBatch(GraphicsDevice);

        playerTexture = Content.Load<Texture2D>(@"Textures\player");
        me = new Player(playerTexture, new Vector2(200, 200));
    }

    protected override void UnloadContent()
    {
        // TODO: Unload any non ContentManager content here
    }

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

        me.Update(gameTime);


        base.Update(gameTime);
    }

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

        spriteBatch.Begin();

        me.Draw(spriteBatch);

        spriteBatch.End();

        base.Draw(gameTime);
    }
}
}

Thanks in advance for your time!

Answer 1

I looked through it, and it looks like you never define the Actor’s color property. This means that the color variable defaults to black, which means that the tint given to the Draw line (spriteBatch.Draw(this.texture, this.position, this.color);) is Black, which hides the sprite.

Just set the color of the Actor to white somewhere (I just set it underneath me = new Player(playerTexture, new Vector2(200, 200));).

So the new LoadContent would look like:

protected override void LoadContent()
{
    // Create a new SpriteBatch, which can be used to draw textures.
    spriteBatch = new SpriteBatch(GraphicsDevice);

    playerTexture = Content.Load<Texture2D>(@"Textures\player");
    me = new Player(playerTexture, new Vector2(200, 200));
    me.Color = Color.White;
}

Hope that helps,
max