Rendering Rays

This is a basic static class that allows easy rendering of Rays in 3D space.

This one is for XNA 4.0.

public static class RayRenderer {
    static VertexPositionColor[] verts = new VertexPositionColor[2];
 
    static VertexPositionColor[] arrowVerts = {
            new VertexPositionColor(Vector3.Zero, Color.White),
            new VertexPositionColor(new Vector3(.5f, 0f, -.5f), Color.White),
            new VertexPositionColor(new Vector3(-.5f, 0f, -.5f), Color.White),
            new VertexPositionColor(new Vector3(0f, .5f, -.5f), Color.White),
            new VertexPositionColor(new Vector3(0f, -.5f, -.5f), Color.White),
        };
 
    static int[] arrowIndexs = {
            0, 1,
            0, 2,
            0, 3,
            0, 4,
        };
 
  //  static VertexDeclaration vertDecl;
    static BasicEffect effect;
 
    /// <summary>
    /// Renders a Ray for debugging purposes.
    /// </summary>
    /// <param name="ray">The ray to render.</param>
    /// <param name="length">The distance along the ray to render.</param>
    /// <param name="graphicsDevice">The graphics device to use when rendering.</param>
    /// <param name="view">The current view matrix.</param>
    /// <param name="projection">The current projection matrix.</param>
    /// <param name="color">The color to use drawing the ray.</param>
    public static void Render(Ray ray, float length, GraphicsDevice graphicsDevice, Matrix view, Matrix projection, Color color) {
      if (effect == null) {
        effect = new BasicEffect(graphicsDevice);
        effect.VertexColorEnabled = false;
        effect.LightingEnabled = false;
      }
 
      verts[0] = new VertexPositionColor(ray.Position, Color.White);
      verts[1] = new VertexPositionColor(ray.Position + (ray.Direction * length), Color.White);
 
      effect.DiffuseColor = color.ToVector3();
      effect.Alpha = (float)color.A / 255f;
 
      effect.World = Matrix.Identity;
      effect.View = view;
      effect.Projection = projection;
 
      //note you may wish to comment these next 2 lines out and set the RasterizerState elswehere in code 
      //rather than here for every ray draw call. 
      RasterizerState rs = graphicsDevice.RasterizerState;
      graphicsDevice.RasterizerState = RasterizerState.CullNone;
 
      foreach (EffectPass pass in effect.CurrentTechnique.Passes) {
        pass.Apply();
 
        graphicsDevice.DrawUserPrimitives(PrimitiveType.LineList, verts, 0, 1);
 
        effect.World = Matrix.Invert(Matrix.CreateLookAt(
            verts[1].Position,
            verts[0].Position,
            (ray.Direction != Vector3.Up) ? Vector3.Up : Vector3.Left));
 
        graphicsDevice.DrawUserIndexedPrimitives(PrimitiveType.LineList, arrowVerts, 0, 5, arrowIndexs, 0, 4);
      }
 
      //note you may wish to comment the next line out and set the RasterizerState elswehere in code 
      //rather than here for every ray draw call. 
      graphicsDevice.RasterizerState = rs;
    }
  }