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// This code was written for the OpenTK library and has been released
// to the Public Domain.
// It is provided "as is" without express or implied warranty of any kind.
#region --- Using directives ---
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Threading;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;
using OpenTK.Platform;
using System.Drawing;
#endregion
namespace Examples.Tutorial
{
[Example("VBO Static", ExampleCategory.OpenGL, "1.x", 3, Documentation = "VBOStatic")]
public class T08_VBO : GameWindow
{
const float rotation_speed = 180.0f;
float angle;
struct Vbo { public int VboID, EboID, NumElements; }
Vbo[] vbo = new Vbo[2];
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) { }
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
Version version = new Version(GL.GetString(StringName.Version).Substring(0, 3));
Version target = new Version(1, 5);
if (version < target)
{
throw new NotSupportedException(String.Format(
"OpenGL {0} is required (you only have {1}).", target, version));
}
GL.ClearColor(System.Drawing.Color.MidnightBlue);
GL.Enable(EnableCap.DepthTest);
vbo[0] = LoadVBO(CubeVertices, CubeElements);
vbo[1] = LoadVBO(CubeVertices, CubeElements);
}
protected override void OnResize(EventArgs e)
{
base.OnResize(e);
GL.Viewport(0, 0, Width, Height);
float aspect_ratio = Width / (float)Height;
Matrix4 perpective = Matrix4.CreatePerspectiveFieldOfView(MathHelper.PiOver4, aspect_ratio, 1, 64);
GL.MatrixMode(MatrixMode.Projection);
GL.LoadMatrix(ref perpective);
}
protected override void OnUpdateFrame(FrameEventArgs e)
{
base.OnUpdateFrame(e);
var keyboard = OpenTK.Input.Keyboard.GetState();
if (keyboard[OpenTK.Input.Key.Escape])
this.Exit();
}
protected override void OnRenderFrame(FrameEventArgs e)
{
base.OnRenderFrame(e);
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
Matrix4 lookat = Matrix4.LookAt(0, 5, 5, 0, 0, 0, 0, 1, 0);
GL.MatrixMode(MatrixMode.Modelview);
GL.LoadMatrix(ref lookat);
angle += rotation_speed * (float)e.Time;
GL.Rotate(angle, 0.0f, 1.0f, 0.0f);
Draw(vbo[0]);
SwapBuffers();
}
Vbo LoadVBO<TVertex>(TVertex[] vertices, short[] elements) where TVertex : struct
{
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 * BlittableValueType.StrideOf(vertices)), vertices,
BufferUsageHint.StaticDraw);
GL.GetBufferParameter(BufferTarget.ArrayBuffer, BufferParameterName.BufferSize, out size);
if (vertices.Length * BlittableValueType.StrideOf(vertices) != size)
throw new ApplicationException("Vertex data not uploaded correctly");
GL.GenBuffers(1, out handle.EboID);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, handle.EboID);
GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(elements.Length * sizeof(short)), elements,
BufferUsageHint.StaticDraw);
GL.GetBufferParameter(BufferTarget.ElementArrayBuffer, BufferParameterName.BufferSize, out size);
if (elements.Length * sizeof(short) != size)
throw new ApplicationException("Element data not uploaded correctly");
handle.NumElements = elements.Length;
return handle;
}
void Draw(Vbo handle)
{
// 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(ArrayCap.ColorArray);
GL.EnableClientState(ArrayCap.VertexArray);
GL.BindBuffer(BufferTarget.ArrayBuffer, handle.VboID);
GL.BindBuffer(BufferTarget.ElementArrayBuffer, handle.EboID);
GL.VertexPointer(3, VertexPointerType.Float, BlittableValueType.StrideOf(CubeVertices), new IntPtr(0));
GL.ColorPointer(4, ColorPointerType.UnsignedByte, BlittableValueType.StrideOf(CubeVertices), new IntPtr(12));
GL.DrawElements(PrimitiveType.Triangles, handle.NumElements, DrawElementsType.UnsignedShort, IntPtr.Zero);
}
/// <summary>
/// Entry point of this example.
/// </summary>
[STAThread]
public static void Main()
{
using (T08_VBO example = new T08_VBO())
{
Utilities.SetWindowTitle(example);
example.Run(30.0, 0.0);
}
}
}
}
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