Cleaned up sample, added color and motion.

Source/Examples/OpenGL/1.5/VertexBufferObject.cs

@@ -16,6 +16,7 @@ using OpenTK;
 using OpenTK.Graphics;
 using OpenTK.Graphics.OpenGL;
 using OpenTK.Platform;
+using System.Drawing;
 
 #endregion
 
@@ -24,28 +25,54 @@ namespace Examples.Tutorial
     [Example("Static Vertex Buffer Objects", ExampleCategory.OpenGL, "VBO", Documentation="VertexBufferObject")]
     public class T08_VBO : GameWindow
     {
-        #region --- Private Fields ---
+        const float rotation_speed = 180.0f;
+        float angle;
         
-        Shapes.Shape cube = new Examples.Shapes.Cube();
+        struct Vbo { public int VboID, EboID, NumElements; }
-
-        struct Vbo
-        {
-            public int VboID, EboID, NumElements;
-        }
         Vbo[] vbo = new Vbo[2];
         
-        public static readonly int order = 8;
+        [StructLayout(LayoutKind.Sequential, Pack = 1)]
+        struct VertexPositionColor
+        {
+            public Vector3 Position;
+            public uint Color;
 
-        #endregion
+            public VertexPositionColor(float x, float y, float z, Color color)
+            {
+                Position = new Vector3(x, y, z);
+                Color = ToRgba(color);
+            }
 
-        #region --- Constructor ---
+            static uint ToRgba(Color color)
+            {
+                return (uint)color.A << 24 | (uint)color.B << 16 | (uint)color.G << 8 | (uint)color.R;
+            }
+        }
+
+        VertexPositionColor[] CubeVertices = new VertexPositionColor[]
+        {
+                new VertexPositionColor(-1.0f, -1.0f,  1.0f, Color.DarkRed),
+                new VertexPositionColor( 1.0f, -1.0f,  1.0f, Color.DarkRed),
+                new VertexPositionColor( 1.0f,  1.0f,  1.0f, Color.Gold),
+                new VertexPositionColor(-1.0f,  1.0f,  1.0f, Color.Gold),
+                new VertexPositionColor(-1.0f, -1.0f, -1.0f, Color.DarkRed),
+                new VertexPositionColor( 1.0f, -1.0f, -1.0f, Color.DarkRed), 
+                new VertexPositionColor( 1.0f,  1.0f, -1.0f, Color.Gold),
+                new VertexPositionColor(-1.0f,  1.0f, -1.0f, Color.Gold) 
+        };
+
+        readonly short[] CubeElements = new short[]
+        {
+            0, 1, 2, 2, 3, 0, // front face
+            3, 2, 6, 6, 7, 3, // top face
+            7, 6, 5, 5, 4, 7, // back face
+            4, 0, 3, 3, 7, 4, // left face
+            0, 1, 5, 5, 4, 0, // bottom face
+            1, 5, 6, 6, 2, 1, // right face
+        };
 
         public T08_VBO() : base(800, 600) { }
 
-        #endregion
-
-        #region OnLoad override
-
         protected override void OnLoad(EventArgs e)
         {
             base.OnLoad(e);
@@ -60,24 +87,17 @@ namespace Examples.Tutorial
                 this.Exit();
             }
 
-            GL.ClearColor(0.1f, 0.1f, 0.5f, 0.0f);
+            GL.ClearColor(System.Drawing.Color.MidnightBlue);
             GL.Enable(EnableCap.DepthTest);
 
-            // Create the Vertex Buffer Object:
+            vbo[0] = LoadVBO(CubeVertices, CubeElements);
-            // 1) Generate the buffer handles.
+            vbo[1] = LoadVBO(CubeVertices, CubeElements);
-            // 2) Bind the Vertex Buffer and upload your vertex buffer. Check that the buffer was uploaded correctly.
-            // 3) Bind the Index Buffer and upload your index buffer. Check that the buffer was uploaded correctly.
-
-            vbo[0] = LoadVBO(cube.Vertices, cube.Indices);
-            vbo[1] = LoadVBO(cube.Vertices, cube.Indices);
         }
 
-        #endregion
-
-        #region OnResize override
-
         protected override void OnResize(EventArgs e)
         {
+            base.OnResize(e);
+
             GL.Viewport(0, 0, Width, Height);
 
             float aspect_ratio = Width / (float)Height;
@@ -86,27 +106,14 @@ namespace Examples.Tutorial
             GL.LoadMatrix(ref perpective);
         }
 
-        #endregion
-
-        #region OnUpdateFrame override
-
-        /// <summary>
-        /// Prepares the next frame for rendering.
-        /// </summary>
-        /// <remarks>
-        /// Place your control logic here. This is the place to respond to user input,
-        /// update object positions etc.
-        /// </remarks>
         protected override void OnUpdateFrame(FrameEventArgs e)
         {
+            base.OnUpdateFrame(e);
+
             if (Keyboard[OpenTK.Input.Key.Escape])
                 this.Exit();
         }
 
-        #endregion
-
-        #region OnRenderFrame
-
         protected override void OnRenderFrame(FrameEventArgs e)
         {
             base.OnRenderFrame(e);
@@ -117,68 +124,65 @@ namespace Examples.Tutorial
             GL.MatrixMode(MatrixMode.Modelview);
             GL.LoadMatrix(ref lookat);
 
-            GL.Color4(System.Drawing.Color.Black);
+            angle += rotation_speed * (float)e.Time;
+            GL.Rotate(angle, 0.0f, 1.0f, 0.0f);
+
             Draw(vbo[0]);
 
             SwapBuffers();
         }
 
-        #endregion
+        Vbo LoadVBO<TVertex>(TVertex[] vertices, short[] elements) where TVertex : struct
-
-        Vbo LoadVBO(Vector3[] vertices, int[] indices)
         {
             Vbo handle = new Vbo();
             int size;
 
+            // To create a VBO:
+            // 1) Generate the buffer handles for the vertex and element buffers.
+            // 2) Bind the vertex buffer handle and upload your vertex data. Check that the buffer was uploaded correctly.
+            // 3) Bind the element buffer handle and upload your element data. Check that the buffer was uploaded correctly.
+
             GL.GenBuffers(1, out handle.VboID);
             GL.BindBuffer(BufferTarget.ArrayBuffer, handle.VboID);
-            GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(vertices.Length * Vector3.SizeInBytes), vertices,
+            GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(vertices.Length * BlittableValueType.StrideOf(vertices)), vertices,
                           BufferUsageHint.StaticDraw);
             GL.GetBufferParameter(BufferTarget.ArrayBuffer, BufferParameterName.BufferSize, out size);
-            if (vertices.Length * Vector3.SizeInBytes != size)
+            if (vertices.Length * BlittableValueType.StrideOf(vertices) != size)
-                throw new ApplicationException("Vertex array not uploaded correctly");
+                throw new ApplicationException("Vertex data not uploaded correctly");
-            //GL.BindBuffer(Version15.ArrayBuffer, 0);
 
             GL.GenBuffers(1, out handle.EboID);
             GL.BindBuffer(BufferTarget.ElementArrayBuffer, handle.EboID);
-            GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(indices.Length * sizeof(int)), indices,
+            GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(elements.Length * sizeof(short)), elements,
                           BufferUsageHint.StaticDraw);
             GL.GetBufferParameter(BufferTarget.ElementArrayBuffer, BufferParameterName.BufferSize, out size);
-            if (indices.Length * sizeof(int) != size)
+            if (elements.Length * sizeof(short) != size)
-                throw new ApplicationException("Element array not uploaded correctly");
+                throw new ApplicationException("Element data not uploaded correctly");
-            //GL.BindBuffer(Version15.ElementArrayBuffer, 0);
 
-            handle.NumElements = indices.Length;
+            handle.NumElements = elements.Length;
             return handle;
         }
 
         void Draw(Vbo handle)
         {
-            //GL.PushClientAttrib(ClientAttribMask.ClientVertexArrayBit);
+            // To draw a VBO:
+            // 1) Ensure that the VertexArray client state is enabled.
+            // 2) Bind the vertex and element buffer handles.
+            // 3) Set up the data pointers (vertex, normal, color) according to your vertex format.
+            // 4) Call DrawElements. (Note: the last parameter is an offset into the element buffer
+            //    and will usually be IntPtr.Zero).
 
-            //GL.EnableClientState(EnableCap.TextureCoordArray);
+            GL.EnableClientState(EnableCap.ColorArray);
             GL.EnableClientState(EnableCap.VertexArray);
 
             GL.BindBuffer(BufferTarget.ArrayBuffer, handle.VboID);
             GL.BindBuffer(BufferTarget.ElementArrayBuffer, handle.EboID);
 
-            //GL.TexCoordPointer(2, TexCoordPointerType.Float, vector2_size, (IntPtr)vector2_size);
+            GL.VertexPointer(3, VertexPointerType.Float, BlittableValueType.StrideOf(CubeVertices), new IntPtr(0));
-            GL.VertexPointer(3, VertexPointerType.Float, Vector3.SizeInBytes, IntPtr.Zero);
+            GL.ColorPointer(4, ColorPointerType.UnsignedByte, BlittableValueType.StrideOf(CubeVertices), new IntPtr(12));
 
-            GL.DrawElements(BeginMode.Triangles, handle.NumElements, DrawElementsType.UnsignedInt, IntPtr.Zero);
+            GL.DrawElements(BeginMode.Triangles, handle.NumElements, DrawElementsType.UnsignedShort, IntPtr.Zero);
-            //GL.DrawArrays(BeginMode.LineLoop, 0, vbo.element_count);
-
-            GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
-            GL.BindBuffer(BufferTarget.ElementArrayBuffer, 0);
-
-            GL.DisableClientState(EnableCap.VertexArray);
-            //GL.DisableClientState(EnableCap.TextureCoordArray);
-
-            //GL.PopClientAttrib();
         }
 
-        #region public static void Main()
-
         /// <summary>
         /// Entry point of this example.
         /// </summary>
@@ -187,13 +191,9 @@ namespace Examples.Tutorial
         {
             using (T08_VBO example = new T08_VBO())
             {
-                // Get the title and category  of this example using reflection.
+                Utilities.SetWindowTitle(example);
-                ExampleAttribute info = ((ExampleAttribute)example.GetType().GetCustomAttributes(false)[0]);
-                example.Title = String.Format("OpenTK | {0} {1}: {2}", info.Category, info.Difficulty, info.Title);
                 example.Run(30.0, 0.0);
             }
         }
-
-        #endregion
     }
 }