Opentk/Source/Examples/OpenTK/GLControl/GLControlGameLoop.cs

// 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.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.Threading;

using OpenTK.Graphics.OpenGL;
using OpenTK.Platform;
using OpenTK;

#endregion

namespace Examples.WinForms
{
    [Example("Simple GLControl Game Loop", ExampleCategory.OpenTK, "GLControl", 2, Documentation="GLControlGameLoop")]
    public partial class GameLoopForm : Form
    {
        static float angle = 0.0f;

        #region --- Constructor ---

        public GameLoopForm()
        {
            InitializeComponent();
        }

        #endregion

        #region OnLoad

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);

            glControl.KeyDown += new KeyEventHandler(glControl_KeyDown);
            glControl.KeyUp += new KeyEventHandler(glControl_KeyUp);
            glControl.Resize += new EventHandler(glControl_Resize);
            glControl.Paint += new PaintEventHandler(glControl_Paint);

            Text =
                GL.GetString(StringName.Vendor) + " " +
                GL.GetString(StringName.Renderer) + " " +
                GL.GetString(StringName.Version);

            GL.ClearColor(Color.MidnightBlue);
            GL.Enable(EnableCap.DepthTest);

            Application.Idle += Application_Idle;

            // Ensure that the viewport and projection matrix are set correctly.
            glControl_Resize(glControl, EventArgs.Empty);
        }

        void glControl_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.F12)
            {
                GrabScreenshot().Save("screenshot.png");
            }
        }

        #endregion

        #region OnClosing

        protected override void OnClosing(CancelEventArgs e)
        {
            Application.Idle -= Application_Idle;

            base.OnClosing(e);
        }

        #endregion

        #region Application_Idle event

        void Application_Idle(object sender, EventArgs e)
        {
            while (glControl.IsIdle)
            {
                Render();
            }
        }

        #endregion

        #region GLControl.Resize event handler

        void glControl_Resize(object sender, EventArgs e)
        {
            OpenTK.GLControl c = sender as OpenTK.GLControl;

            if (c.ClientSize.Height == 0)
                c.ClientSize = new System.Drawing.Size(c.ClientSize.Width, 1);

            GL.Viewport(0, 0, c.ClientSize.Width, c.ClientSize.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);
        }

        #endregion

        #region GLControl.KeyDown event handler

        void glControl_KeyDown(object sender, KeyEventArgs e)
        {
            switch (e.KeyData)
            {
                case Keys.Escape:
                    this.Close();
                    break;
            }
        }

        #endregion

        #region GLControl.Paint event handler

        void glControl_Paint(object sender, PaintEventArgs e)
        {
            Render();
        }

        #endregion

        #region private void Render()

        private void Render()
        {
            Matrix4 lookat = Matrix4.LookAt(0, 5, 5, 0, 0, 0, 0, 1, 0);
            GL.MatrixMode(MatrixMode.Modelview);
            GL.LoadMatrix(ref lookat);

            GL.Rotate(angle, 0.0f, 1.0f, 0.0f);
            angle += 0.5f;

            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

            DrawCube();

            glControl.SwapBuffers();
        }

        #endregion

		#region private void DrawCube()

        private void DrawCube()
        {
            GL.Begin(BeginMode.Quads);

            GL.Color3(Color.Silver);
            GL.Vertex3(-1.0f, -1.0f, -1.0f);
            GL.Vertex3(-1.0f, 1.0f, -1.0f);
            GL.Vertex3(1.0f, 1.0f, -1.0f);
            GL.Vertex3(1.0f, -1.0f, -1.0f);

            GL.Color3(Color.Honeydew);
            GL.Vertex3(-1.0f, -1.0f, -1.0f);
            GL.Vertex3(1.0f, -1.0f, -1.0f);
            GL.Vertex3(1.0f, -1.0f, 1.0f);
            GL.Vertex3(-1.0f, -1.0f, 1.0f);

            GL.Color3(Color.Moccasin);

            GL.Vertex3(-1.0f, -1.0f, -1.0f);
            GL.Vertex3(-1.0f, -1.0f, 1.0f);
            GL.Vertex3(-1.0f, 1.0f, 1.0f);
            GL.Vertex3(-1.0f, 1.0f, -1.0f);

            GL.Color3(Color.IndianRed);
            GL.Vertex3(-1.0f, -1.0f, 1.0f);
            GL.Vertex3(1.0f, -1.0f, 1.0f);
            GL.Vertex3(1.0f, 1.0f, 1.0f);
            GL.Vertex3(-1.0f, 1.0f, 1.0f);

            GL.Color3(Color.PaleVioletRed);
            GL.Vertex3(-1.0f, 1.0f, -1.0f);
            GL.Vertex3(-1.0f, 1.0f, 1.0f);
            GL.Vertex3(1.0f, 1.0f, 1.0f);
            GL.Vertex3(1.0f, 1.0f, -1.0f);

            GL.Color3(Color.ForestGreen);
            GL.Vertex3(1.0f, -1.0f, -1.0f);
            GL.Vertex3(1.0f, 1.0f, -1.0f);
            GL.Vertex3(1.0f, 1.0f, 1.0f);
            GL.Vertex3(1.0f, -1.0f, 1.0f);

            GL.End();
        }

        #endregion

        #region private void GrabScreenshot()

        Bitmap GrabScreenshot()
        {
            Bitmap bmp = new Bitmap(this.ClientSize.Width, this.ClientSize.Height);
            System.Drawing.Imaging.BitmapData data =
            bmp.LockBits(this.ClientRectangle, System.Drawing.Imaging.ImageLockMode.WriteOnly,
                System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            GL.ReadPixels(0, 0, this.ClientSize.Width, this.ClientSize.Height, PixelFormat.Bgr, PixelType.UnsignedByte,
                data.Scan0);
            bmp.UnlockBits(data);
            bmp.RotateFlip(RotateFlipType.RotateNoneFlipY);
            return bmp;
        }

        #endregion

        #region public static void Main()

        /// <summary>
        /// Entry point of this example.
        /// </summary>
        [STAThread]
        public static void Main()
        {
            using (GameLoopForm example = new GameLoopForm())
            {
                // Get the title and category  of this example using reflection.
                ExampleAttribute info = ((ExampleAttribute)example.GetType().GetCustomAttributes(false)[0]);
                example.Text = String.Format("OpenTK | {0} {1}: {2}", info.Category, info.Difficulty, info.Title);
                example.ShowDialog();
            }
        }

        #endregion
    }
}