// 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.Windows.Forms;
using System.Threading;
using System.Drawing;

using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.ES11;

#endregion

namespace Examples.Tutorial
{
#if EXPERIMENTAL
    [Example("Immediate mode", ExampleCategory.OpenGLES, "1.1", Documentation = "SimpleES11Window")]
    public class SimpleES11Window : GameWindow
    {
        #region --- Fields ---

        float rotation_speed = 3.0f;
        float angle;

        #endregion

        #region --- Constructor ---

        public SimpleES11Window()
            : base(800, 600, new GraphicsMode(16, 16), "", GameWindowFlags.Default, DisplayDevice.Default, 2, 0, GraphicsContextFlags.Embedded)
        { }

        #endregion

        #region OnLoad

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

            Color4 color = Color4.MidnightBlue;
            GL.ClearColor(color.R, color.G, color.B, color.A);
            GL.Enable((All)EnableCap.DepthTest);
        }

        #endregion

    #region OnResize

        /// <summary>
        /// Called when the user resizes the window.
        /// </summary>
        /// <param name="e">Contains the new width/height of the window.</param>
        /// <remarks>
        /// You want the OpenGL viewport to match the window. This is the place to do it!
        /// </remarks>
        protected override void OnResize(EventArgs e)
        {
            GL.Viewport(0, 0, Width, Height);

            double aspect_ratio = Width / (double)Height;

            OpenTK.Matrix4 perspective = OpenTK.Matrix4.CreatePerspectiveFieldOfView(MathHelper.PiOver4, (float)aspect_ratio, 1, 64);
            GL.MatrixMode((All)MatrixMode.Projection);
            GL.LoadMatrix(ref perspective.Row0.X);
        }

        #endregion

    #region OnUpdateFrame

        /// <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)
        {
            if (Keyboard[OpenTK.Input.Key.Escape])
            {
                this.Exit();
                return;
            }
        }

        #endregion

    #region OnRenderFrame

        /// <summary>
        /// Place your rendering code here.
        /// </summary>
        protected override void OnRenderFrame(FrameEventArgs e)
        {
            GL.Clear((uint)(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit));

            Matrix4 lookat = Matrix4.LookAt(0, 5, 5, 0, 0, 0, 0, 1, 0);
            GL.MatrixMode((All)MatrixMode.Modelview);
            GL.LoadMatrix(ref lookat.Row0.X);

            angle += rotation_speed * (float)e.Time;
            GL.Rotate(angle, 0.0f, 1.0f, 0.0f);

            DrawCube();

            this.SwapBuffers();
        }

        #endregion

    #region private void DrawCube()

        private void DrawCube()
        {
#if false
            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();
#endif
        }

        #endregion

    #region public static void Main()

        /// <summary>
        /// Entry point of this example.
        /// </summary>
        [STAThread]
        public static void Main()
        {
            using (SimpleES11Window example = new SimpleES11Window())
            {
                Utilities.SetWindowTitle(example);
                example.Run(30.0, 0.0);
            }
        }

        #endregion
    }
#endif
}