Primitives in XNA consists of lines and triangle based primitives. Primitives are used to build simple graphical structures in XNA without the use of a DCC tool. The main things needed to rendera primitive are;
#region Using Statements
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Storage;
#endregion
namespace drawprimitives
{
///
/// This is the main type for your game
///
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
ContentManager content;
VertexPositionColor[] vertices = new VertexPositionColor[6];
VertexDeclaration vertexDeclaration;
BasicEffect basicEffect;
float angle;
public Game1()
{
graphics = new GraphicsDeviceManager(this);
content = new ContentManager(Services);
}
///
/// 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.
///
protected override void Initialize()
{
// TODO: Add your initialization logic here
basicEffect = new BasicEffect(graphics.GraphicsDevice, null);
basicEffect.VertexColorEnabled = true;
basicEffect.View = Matrix.CreateLookAt(new Vector3(0, 0, 500), new Vector3(0, 0, 0), Vector3.Up);
basicEffect.Projection= Matrix.CreatePerspectiveFieldOfView((float)Math.PI / 4.0f,
(float)graphics.GraphicsDevice.Viewport.Width / (float)graphics.GraphicsDevice.Viewport.Height,
0.1f,
100000);
// create a vertex declaration, which tells the graphics card what kind of
// data to expect during a draw call. We're drawing using
// VertexPositionColors, so we'll use those vertex elements.
vertexDeclaration = new VertexDeclaration(graphics.GraphicsDevice, VertexPositionColor.VertexElements);
// create our triangle
// because our triangle consist of 3 lines, we need 6 vertices (for each line the beginning and the ending).
// notice that we have to send some vertices twice to our graphics card.
vertices[0].Position = new Vector3(0, 0, 0);
vertices[0].Color = Color.Red;
vertices[1].Position = new Vector3(0, 100, 0);
vertices[1].Color = Color.Red;
vertices[2].Position = new Vector3(0, 100, 0);
vertices[2].Color = Color.Red;
vertices[3].Position = new Vector3(100, 100, 0);
vertices[3].Color = Color.Red;
vertices[4].Position = new Vector3(100, 100, 0);
vertices[4].Color = Color.Red;
vertices[5].Position = new Vector3(0, 0, 0);
vertices[5].Color = Color.Red;
base.Initialize();
}
///
/// Load your graphics content. If loadAllContent is true, you should
/// load content from both ResourceManagementMode pools. Otherwise, just
/// load ResourceManagementMode.Manual content.
///
/// Which type of content to load.
protected override void LoadGraphicsContent(bool loadAllContent)
{
if (loadAllContent)
{
// TODO: Load any ResourceManagementMode.Automatic content
}
// TODO: Load any ResourceManagementMode.Manual content
}
///
/// Unload your graphics content. If unloadAllContent is true, you should
/// unload content from both ResourceManagementMode pools. Otherwise, just
/// unload ResourceManagementMode.Manual content. Manual content will get
/// Disposed by the GraphicsDevice during a Reset.
///
///Which type of content to unload.
protected override void UnloadGraphicsContent(bool unloadAllContent)
{
if (unloadAllContent == true)
{
content.Unload();
}
}
///
/// Allows the game to run logic such as updating the world,
/// checking for collisions, gathering input and playing audio.
///
/// Provides a snapshot of timing values.
protected override void Update(GameTime gameTime)
{
// Allows the default game to exit on Xbox 360 and Windows
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
// TODO: Add your update logic here
base.Update(gameTime);
}
///
/// This is called when the game should draw itself.
///
/// Provides a snapshot of timing values.
protected override void Draw(GameTime gameTime)
{
graphics.GraphicsDevice.Clear(Color.CornflowerBlue);
graphics.GraphicsDevice.RenderState.CullMode = CullMode.None;
// TODO: Add your drawing code here
graphics.GraphicsDevice.VertexDeclaration = vertexDeclaration;
// tell our basic effect to begin.
angle += 0.01f;
basicEffect.World = Matrix.CreateRotationZ(angle);
basicEffect.Begin();
basicEffect.CurrentTechnique.Passes[0].Begin();
graphics.GraphicsDevice.DrawUserPrimitives(PrimitiveType.LineList, vertices, 0, 3);
// tell basic effect that we're done.
basicEffect.CurrentTechnique.Passes[0].End();
basicEffect.End();
base.Draw(gameTime);
}
}
}