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Drawing a Grid in OpenTK

A simple method to drawing a grid in GL with all the fixings
This can also be useful with the Camera2D/Camera3D classes

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public void DrawGrid(System.Drawing.Color color, float X, float Y, int cell_size = 16, int grid_size = 256)
{
    int dX = (int)Math.Round(X / cell_size) * cell_size;
    int dZ = (int)Math.Round(Z / cell_size) * cell_size;

    int ratio = grid_size / cell_size;

    GL.PushMatrix();

    GL.Translate(dX - grid_size / 2, 0, dZ - grid_size / 2);

    int i;

    GL.Color3(color);
    GL.Begin(BeginMode.Lines);

    for (i = 0; i < ratio + 1; i++)
    {
        int current = i * cell_size;

        GL.Vertex3(current, 0, 0);
        GL.Vertex3(current, 0, grid_size);

        GL.Vertex3(0, 0, current);
        GL.Vertex3(grid_size, 0, current);
    }

    GL.End();

    GL.PopMatrix();
}

-Update-
Made a little example of a grid using fog.



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namespace Tutorial
{
    class Main : GameWindow
    {
        private Camera3D camera;
        private int cell_size = 32;
        private int grid_size = 4096;

        public Main()
            : base(800, 600)
        {
            Title = "Grid";
        }

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

            GL.ClearColor(0.0f, 0.0f, 0.0f, 0.0f);

            GL.Enable(EnableCap.Fog);
            GL.Fog(FogParameter.FogColor, new float[4] { 0.0f, 0.0f, 0.0f, 1.0f });//Same color as clear.
            GL.Fog(FogParameter.FogMode, (int)FogMode.Linear);
            GL.Fog(FogParameter.FogEnd, (float)(grid_size / 3.0f));

            camera = new Camera3D(0, 1, 0);

            this.Mouse.Move += new EventHandler<OpenTK.Input.MouseMoveEventArgs>(Mouse_Move);
        }

        private void Mouse_Move(object sender, OpenTK.Input.MouseMoveEventArgs e)
        {
            int dX = e.XDelta;
            int dY = e.YDelta;

            camera.RotationX += (float)dY / 5.0f;
            camera.RotationY += (float)dX / 5.0f;
        }

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

            GL.Viewport(0, 0, Width, Height);

            OpenTK.Matrix4 matrix = OpenTK.Matrix4.CreatePerspectiveFieldOfView(1.0f, (Width / (float)Height), 1.0f, 10000.0f);

            GL.MatrixMode(MatrixMode.Projection);
            GL.LoadMatrix(ref matrix);
        }

        protected override void OnUpdateFrame(FrameEventArgs e)
        {
            base.OnUpdateFrame(e);

            if (Keyboard[OpenTK.Input.Key.W])
                camera.Move(Camera3D.Direction.Forward);
            if (Keyboard[OpenTK.Input.Key.S])
                camera.Move(Camera3D.Direction.Backward);
            if (Keyboard[OpenTK.Input.Key.A])
                camera.Move(Camera3D.Direction.Left);
            if (Keyboard[OpenTK.Input.Key.D])
                camera.Move(Camera3D.Direction.Right);
            if (Keyboard[OpenTK.Input.Key.Q])
                camera.Move(Camera3D.Direction.Up);
            if (Keyboard[OpenTK.Input.Key.E])
                camera.Move(Camera3D.Direction.Down);

            if (Keyboard[OpenTK.Input.Key.Number1])
            {
                GL.Enable(EnableCap.Fog);
            }
            if (Keyboard[OpenTK.Input.Key.Number2])
            {
                GL.Disable(EnableCap.Fog);
            }
        }

        protected override void OnRenderFrame(FrameEventArgs e)
        {
            base.OnRenderFrame(e);

            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
            GL.MatrixMode(MatrixMode.Modelview);
            GL.LoadIdentity();

            camera.Update();
            camera.DrawGrid(System.Drawing.Color.LimeGreen, cell_size, grid_size);

            SwapBuffers();
        }
    }
}

5 comments :

  1. Hi, how to capture the mouse in the game?

    ReplyDelete
  2. This comment has been removed by the author.

    ReplyDelete
  3. Hi, i will ask you:

    Can be used for GLControl also?

    Sorry for my english ;)

    ReplyDelete
  4. It complained at Camera3D

    I've got the following USINGS:
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Drawing;
    using OpenTK;

    ReplyDelete