XNA Essentials

Game Programming for Xbox 360, PC + Windows Phone


Chapter 4 - Triangle not rendering

I've followed the XNADemo code in chapter 4 up to page 66.

I should have a textured triangle on the screen but I get just the plain cornflower blue screen.

Here is my code listing.

Any help is much appreciated.

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

        private Matrix projection;
        private Matrix view;
        private Matrix world;

        private Vector3 cameraPosition = new Vector3(0.0f, 0.0f, 3.0f);
        private Vector3 cameraTarget = Vector3.Zero;
        private Vector3 cameraUpVector = Vector3.Up;

        private VertexPositionNormalTexture[] vertices;
        private Texture2D texture;
        private BasicEffect effect;

        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

        /// <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>("texture");
            effect = new BasicEffect(graphics.GraphicsDevice, null);


        /// <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)

            // TODO: Add your update logic here


        /// <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)
            world = Matrix.Identity;

            graphics.GraphicsDevice.VertexDeclaration = new VertexDeclaration
                (graphics.GraphicsDevice, VertexPositionNormalTexture.VertexElements);

            effect.Projection = projection;
            effect.View = view;


            effect.World = world;
            effect.TextureEnabled = true;
            effect.Texture = texture;

            foreach (EffectPass pass in effect.CurrentTechnique.Passes)
                    (PrimitiveType.TriangleList, vertices, 0, vertices.Length / 3);



        private void InitializeCamera()
            float aspectRatio = (float)graphics.GraphicsDevice.Viewport.Width /
            Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, aspectRatio, 0.0001f, 1000.0f, out projection);

            Matrix.CreateLookAt(ref cameraPosition, ref cameraTarget, ref cameraUpVector, out view);


        private void InitializeVertices()
            Vector3 position;
            Vector2 textureCoordinates;

            vertices = new VertexPositionNormalTexture[3];

            //top left
            position = new Vector3(-1, 1, 0);
            textureCoordinates = new Vector2(0, 0);
            vertices[0] = new VertexPositionNormalTexture(position, Vector3.Forward, textureCoordinates);

            //bottom right
            position = new Vector3(1, -1, 0);
            textureCoordinates = new Vector2(1, 1);
            vertices[1] = new VertexPositionNormalTexture(position, Vector3.Forward, textureCoordinates);

            //bottom left
            position = new Vector3(-1, -1, 0);
            textureCoordinates = new Vector2(0, 1);
            vertices[1] = new VertexPositionNormalTexture(position, Vector3.Forward, textureCoordinates); 

Spidey - Saturday, October 31, 2009 @ 9:41 AM

Re: Chapter 4 - Triangle not rendering

ok, i just got the answer

I didn't change the index value to 2 for the 3rd vertex in InitializeVertices()

Spidey - Saturday, October 31, 2009 @ 11:11 AM