InvalidCallException in 3D primitives code attempt

Lacking full examples in the docs, I threw together some of the sample code in the How to: Draw 3D Primitives section, probably incorrectly, and am getting an InvalidCallException on the following line:

graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleList, 12, nonIndexedCube);

The details of the exception are not helpful. They say "External component has thrown an exception." My code is below, hopefully this forum formats it ok, without smiley faces etc.

Any suggestions appreciated. By the way, I am using an ATI Radeon Mobility X600 and had no problems compiling and running the Spacewar demo.

- Matteus

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Components;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Storage;

namespace _dTest
{
/// <summary>
/// This is the main type for your game
/// </summary>
partial class Game1 : Microsoft.Xna.Framework.Game
{

VertexPositionColor[] nonIndexedCube;

public Game1()
{
InitializeComponent();

nonIndexedCube = new VertexPositionColor[36];

Vector3 topLeftFront = new Vector3(-1.0f, 1.0f, 1.0f);
Vector3 bottomLeftFront = new Vector3(-1.0f, -1.0f, 1.0f);
Vector3 topRightFront = new Vector3(1.0f, 1.0f, 1.0f);
Vector3 bottomRightFront = new Vector3(1.0f, -1.0f, 1.0f);
Vector3 topLeftBack = new Vector3(-1.0f, 1.0f, -1.0f);
Vector3 topRightBack = new Vector3(1.0f, 1.0f, -1.0f);
Vector3 bottomLeftBack = new Vector3(-1.0f, -1.0f, -1.0f);
Vector3 bottomRightBack = new Vector3(1.0f, -1.0f, -1.0f);

// Front face
nonIndexedCube[0] =
new VertexPositionColor( topLeftFront, Color.Red );
nonIndexedCube[1] =
new VertexPositionColor( bottomLeftFront, Color.Red );
nonIndexedCube[2] =
new VertexPositionColor( topRightFront, Color.Red );
nonIndexedCube[3] =
new VertexPositionColor( bottomLeftFront, Color.Red );
nonIndexedCube[4] =
new VertexPositionColor( bottomRightFront, Color.Red );
nonIndexedCube[5] =
new VertexPositionColor( topRightFront, Color.Red );

// Back face
nonIndexedCube =
new VertexPositionColor( topLeftBack, Color.Orange );
nonIndexedCube[7] =
new VertexPositionColor( topRightBack, Color.Orange );
nonIndexedCube =
new VertexPositionColor( bottomLeftBack, Color.Orange );
nonIndexedCube[9] =
new VertexPositionColor( bottomLeftBack, Color.Orange );
nonIndexedCube[10] =
new VertexPositionColor( topRightBack, Color.Orange );
nonIndexedCube[11] =
new VertexPositionColor( bottomRightBack, Color.Orange );

// Top face
nonIndexedCube[12] =
new VertexPositionColor( topLeftFront, Color.Yellow );
nonIndexedCube[13] =
new VertexPositionColor( topRightBack, Color.Yellow );
nonIndexedCube[14] =
new VertexPositionColor( topLeftBack, Color.Yellow );
nonIndexedCube[15] =
new VertexPositionColor( topLeftFront, Color.Yellow );
nonIndexedCube[16] =
new VertexPositionColor( topRightFront, Color.Yellow );
nonIndexedCube[17] =
new VertexPositionColor( topRightBack, Color.Yellow );

// Bottom face
nonIndexedCube[18] =
new VertexPositionColor( bottomLeftFront, Color.Purple );
nonIndexedCube[19] =
new VertexPositionColor( bottomLeftBack, Color.Purple );
nonIndexedCube[20] =
new VertexPositionColor( bottomRightBack, Color.Purple );
nonIndexedCube[21] =
new VertexPositionColor( bottomLeftFront, Color.Purple );
nonIndexedCube[22] =
new VertexPositionColor( bottomRightBack, Color.Purple );
nonIndexedCube[23] =
new VertexPositionColor( bottomRightFront, Color.Purple );

// Left face
nonIndexedCube[24] =
new VertexPositionColor( topLeftFront, Color.Blue );
nonIndexedCube[25] =
new VertexPositionColor( bottomLeftBack, Color.Blue );
nonIndexedCube[26] =
new VertexPositionColor( bottomLeftFront, Color.Blue );
nonIndexedCube[27] =
new VertexPositionColor( topLeftBack, Color.Blue );
nonIndexedCube[28] =
new VertexPositionColor( bottomLeftBack, Color.Blue );
nonIndexedCube[29] =
new VertexPositionColor( topLeftFront, Color.Blue );

// Right face
nonIndexedCube[30] =
new VertexPositionColor( topRightFront, Color.Green );
nonIndexedCube[31] =
new VertexPositionColor( bottomRightFront, Color.Green );
nonIndexedCube[32] =
new VertexPositionColor( bottomRightBack, Color.Green );
nonIndexedCube[33] =
new VertexPositionColor( topRightBack, Color.Green );
nonIndexedCube[34] =
new VertexPositionColor( topRightFront, Color.Green );
nonIndexedCube[35] =
new VertexPositionColor( bottomRightBack, Color.Green );
}

protected override void Update()
{
// The time since Update was called last
float elapsed = (float)ElapsedTime.TotalSeconds;

// TODO: Add your game logic here

// Let the GameComponents update
UpdateComponents();
}

protected override void Draw()
{
// Make sure we have a valid device
if (!graphics.EnsureDevice())
{
return;
}

graphics.GraphicsDevice.Clear(Color.CornflowerBlue);
using (VertexDeclaration decl = new VertexDeclaration(
graphics.GraphicsDevice, VertexPositionColor.VertexElements))
{
graphics.GraphicsDevice.VertexDeclaration = decl;
graphics.GraphicsDevice.RenderState.CullMode =
CullMode.CullClockwiseFace;
graphics.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleList, 12, nonIndexedCube);
}
graphics.GraphicsDevice.EndScene();
graphics.GraphicsDevice.Present();

}
}
}

[6134 byte] By [MatteusX] at [2007-12-25]