public void VertexTextureVisualTest()
        {
            // Implements an extremely simple terrain that reads from a heightmap in the vertex shader.

            Game.DrawWith += (sender, e) =>
            {
                const int heightMapSize    = 64;
                var       heightMapTexture = new Texture2D(Game.GraphicsDevice, heightMapSize, heightMapSize, false, SurfaceFormat.Single);
                var       heightMapData    = new float[heightMapSize * heightMapSize];
                for (var y = 0; y < heightMapSize; y++)
                {
                    for (var x = 0; x < heightMapSize; x++)
                    {
                        heightMapData[(y * heightMapSize) + x] = (float)Math.Sin(x / 2.0f) + (float)Math.Sin(y / 3.0f);
                    }
                }
                heightMapTexture.SetData(heightMapData);

                var viewMatrix       = Matrix.CreateLookAt(new Vector3(32, 10, 60), new Vector3(32, 0, 30), Vector3.Up);
                var projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4,
                                                                           Game.GraphicsDevice.Viewport.AspectRatio, 1.0f, 100.0f);

                var effect = AssetTestUtility.CompileEffect(Game.GraphicsDevice, "VertexTextureEffect.fx");
                effect.Parameters["WorldViewProj"].SetValue(viewMatrix * projectionMatrix);
                effect.Parameters["HeightMapTexture"].SetValue(heightMapTexture);
                effect.Parameters["HeightMapSize"].SetValue((float)heightMapSize);

                effect.CurrentTechnique.Passes[0].Apply();

                const int numVertices  = heightMapSize * heightMapSize;
                var       vertexBuffer = new VertexBuffer(Game.GraphicsDevice, typeof(VertexPosition2), numVertices, BufferUsage.WriteOnly);
                var       vertices     = new VertexPosition2[numVertices];
                for (var y = 0; y < heightMapSize; y++)
                {
                    for (var x = 0; x < heightMapSize; x++)
                    {
                        vertices[(y * heightMapSize) + x] = new VertexPosition2 {
                            Position = new Vector2(x, y)
                        }
                    }
                }
                ;
                vertexBuffer.SetData(vertices);
                Game.GraphicsDevice.SetVertexBuffer(vertexBuffer);

                const int numIndices  = (heightMapSize - 1) * (heightMapSize - 1) * 2 * 3;
                var       indexBuffer = new IndexBuffer(Game.GraphicsDevice, IndexElementSize.SixteenBits, numIndices, BufferUsage.WriteOnly);
                var       indexData   = new short[numIndices];
                var       indexIndex  = 0;
                for (short y = 0; y < heightMapSize - 1; y++)
                {
                    for (short x = 0; x < heightMapSize - 1; x++)
                    {
                        var baseIndex = (short)((y * heightMapSize) + x);

                        indexData[indexIndex++] = baseIndex;
                        indexData[indexIndex++] = (short)(baseIndex + heightMapSize);
                        indexData[indexIndex++] = (short)(baseIndex + 1);

                        indexData[indexIndex++] = (short)(baseIndex + 1);
                        indexData[indexIndex++] = (short)(baseIndex + heightMapSize);
                        indexData[indexIndex++] = (short)(baseIndex + heightMapSize + 1);
                    }
                }
                indexBuffer.SetData(indexData);
                Game.GraphicsDevice.Indices = indexBuffer;

                Game.GraphicsDevice.RasterizerState = RasterizerState.CullNone;

                Game.GraphicsDevice.Clear(Color.CornflowerBlue);

                Game.GraphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList,
                                                          0, 0, numVertices, 0, numIndices / 3);
            };
            RunSingleFrameTest();
        }
        public void VertexTextureVisualTest()
        {
            // Implements an extremely simple terrain that reads from a heightmap in the vertex shader.

            Game.DrawWith += (sender, e) =>
            {
                const int heightMapSize = 64;
                var heightMapTexture = new Texture2D(Game.GraphicsDevice, heightMapSize, heightMapSize, false, SurfaceFormat.Single);
                var heightMapData = new float[heightMapSize * heightMapSize];
                for (var y = 0; y < heightMapSize; y++)
                    for (var x = 0; x < heightMapSize; x++)
                        heightMapData[(y * heightMapSize) + x] = (float) Math.Sin(x / 2.0f) + (float) Math.Sin(y / 3.0f);
                heightMapTexture.SetData(heightMapData);

                var viewMatrix = Matrix.CreateLookAt(new Vector3(32, 10, 60), new Vector3(32, 0, 30), Vector3.Up);
                var projectionMatrix = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4,
                    Game.GraphicsDevice.Viewport.AspectRatio, 1.0f, 100.0f);

                var effect = AssetTestUtility.CompileEffect(Game.GraphicsDevice, "VertexTextureEffect.fx");
                effect.Parameters["WorldViewProj"].SetValue(viewMatrix * projectionMatrix);
                effect.Parameters["HeightMapTexture"].SetValue(heightMapTexture);
                effect.Parameters["HeightMapSize"].SetValue((float) heightMapSize);

                effect.CurrentTechnique.Passes[0].Apply();

                const int numVertices = heightMapSize * heightMapSize;
                var vertexBuffer = new VertexBuffer(Game.GraphicsDevice, typeof(VertexPosition2), numVertices, BufferUsage.WriteOnly);
                var vertices = new VertexPosition2[numVertices];
                for (var y = 0; y < heightMapSize; y++)
                    for (var x = 0; x < heightMapSize; x++)
                        vertices[(y * heightMapSize) + x] = new VertexPosition2 { Position = new Vector2(x, y) };
                vertexBuffer.SetData(vertices);
                Game.GraphicsDevice.SetVertexBuffer(vertexBuffer);

                const int numIndices = (heightMapSize - 1) * (heightMapSize - 1) * 2 * 3;
                var indexBuffer = new IndexBuffer(Game.GraphicsDevice, IndexElementSize.SixteenBits, numIndices, BufferUsage.WriteOnly);
                var indexData = new short[numIndices];
                var indexIndex = 0;
                for (short y = 0; y < heightMapSize - 1; y++)
                    for (short x = 0; x < heightMapSize - 1; x++)
                    {
                        var baseIndex = (short) ((y * heightMapSize) + x);

                        indexData[indexIndex++] = baseIndex;
                        indexData[indexIndex++] = (short) (baseIndex + heightMapSize);
                        indexData[indexIndex++] = (short) (baseIndex + 1);

                        indexData[indexIndex++] = (short) (baseIndex + 1);
                        indexData[indexIndex++] = (short) (baseIndex + heightMapSize);
                        indexData[indexIndex++] = (short) (baseIndex + heightMapSize + 1);
                    }
                indexBuffer.SetData(indexData);
                Game.GraphicsDevice.Indices = indexBuffer;

                Game.GraphicsDevice.RasterizerState = RasterizerState.CullNone;

                Game.GraphicsDevice.Clear(Color.CornflowerBlue);

                Game.GraphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList,
                    0, 0, numVertices, 0, numIndices / 3);
            };
            RunSingleFrameTest();
        }