I've been experimenting with drawing lines in XNA. I've got no trouble drawing lines in the X and Y directions, but whenever I try and add Z data to the points, there seems to be no effect.
Here's what I was hoping I could do by adding Z information (which I've simulated here by altering the Y and averaging the X points with the midpoint)
And here's what I'm actually getting (I've translated the 2nd line upwards to verify that there are, in fact, two lines getting drawn - when I only change the Z, the two lines get drawn on top of each other)
Am I messing up something basic with my perspective matrix? Skipping an important step? Code below is for the 2nd picture.
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 WindowsGame3
{
/// <summary>
/// This is the main type for your game
/// </summary>
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
BasicEffect baseEffect;
VertexPositionColor[] vertices;
VertexPositionColor[] verticesTop;
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()
{
float AspectRatio = graphics.GraphicsDevice.Viewport.AspectRatio;
baseEffect = new BasicEffect(graphics.GraphicsDevice);
baseEffect.World = Matrix.Identity;
baseEffect.View = Matrix.Identity;
baseEffect.VertexColorEnabled = true;
baseEffect.Projection = Matrix.CreateOrthographicOffCenter
(0, graphics.GraphicsDevice.Viewport.Width, // left, right
graphics.GraphicsDevice.Viewport.Height, 0, // bottom, top
-100, 100); // near, far plane
vertices = new VertexPositionColor[7];
verticesTop = new VertexPositionColor[7];
vertices[0].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 1/8, graphics.GraphicsDevice.Viewport.Height * 5/7, 0);
vertices[0].Color = Color.Black;
vertices[1].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 2/8, graphics.GraphicsDevice.Viewport.Height * 5/7, 1/8);
vertices[1].Color = Color.Red;
vertices[2].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 3 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, -2/8);
vertices[2].Color = Color.Black;
vertices[3].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 4 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, 3/8);
vertices[3].Color = Color.Red;
vertices[4].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 5 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, -4/8);
vertices[4].Color = Color.Black;
vertices[5].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 6 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, 5/8);
vertices[5].Color = Color.Red;
vertices[6].Position = new Vector3(graphics.GraphicsDevice.Viewport.Width * 7 / 8, graphics.GraphicsDevice.Viewport.Height * 5 / 7, -6/8);
vertices[6].Color = Color.Black;
for (int i = 0; i < 7; i++)
{
verticesTop[i] = vertices[i];
verticesTop[i].Position.Y -= 200; // remove this line once perspective is working
verticesTop[i].Position.Z += 100;
}
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);
// 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
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);
baseEffect.CurrentTechnique.Passes[0].Apply();
graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.LineStrip, vertices, 0, 6);
graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.LineStrip, verticesTop, 0, 6);
base.Draw(gameTime);
}
}
}
baseEffect.View = Matrix.Identity;seems to indicate that. – Bart