why gl.vector3 doesn't work?

Question

I want to show a pixel in the screen.I use openTk in Vs2010. this is my code in Windows form application:

private void glControl1_Load(object sender, EventArgs e)
    {
        OpenTK.Graphics.OpenGL.GL.ClearColor(Color.DeepSkyBlue);
        OpenTK.Graphics.OpenGL.GL.Color3(Color.Black);
    }


private void glControl1_Paint(object sender, PaintEventArgs e)
    {
        OpenTK.Graphics.OpenGL.GL.Clear(OpenTK.Graphics.OpenGL.ClearBufferMask.ColorBufferBit|OpenTK.Graphics.OpenGL.ClearBufferMask.DepthBufferBit);
        OpenTK.Graphics.OpenGL.GL.MatrixMode(MatrixMode.Modelview);
        OpenTK.Graphics.OpenGL.GL.LoadIdentity();

        OpenTK.Graphics.OpenGL.GL.Begin(BeginMode.Points);
        OpenTK.Graphics.OpenGL.GL.Vertex3(3,5,9);
      OpenTK.Graphics.OpenGL.GL.End(); 
       glControl1.SwapBuffers();
               }

when I run my code I just see a Blue screen.I don't know what is wrong!!!

I've never worked with these components, but I'm not seeing mostly calls to static methods... How do these calls connect to this (as in your form, control, or whatever visual component you're using)? — RQDQ, Aug 02 '12 at 14:02

score 1 · Answer 1 · answered Aug 02 '12 at 14:13

1

In order to display anything you will need to set the transformation matrices for projection. In your code you are not setting anything which means that the rendering will not have any idea on where to put your point.

I'd suggest looking into some basic tutorial for working with low-level OpenGL. Most of it should be applicable to your scenario.

answered Aug 02 '12 at 14:13

Dervall

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thnx,I set the transformation matrices but still I cant see the pixel. – Sahar Tarighat Aug 03 '12 at 12:28

score 0 · Answer 2 · answered Aug 22 '12 at 19:56

Take a look at opentk glcontrol-based apps

using System;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;
using System.Diagnostics;

namespace GLControlApp
{
  public partial class Form1 : Form
  {
    bool loaded = false;

    public Form1()
    {
      InitializeComponent();
    }

    Stopwatch sw = new Stopwatch(); // available to all event handlers
    private void glControl1_Load(object sender, EventArgs e)
    {
      loaded = true;
      GL.ClearColor(Color.SkyBlue); // Yey! .NET Colors can be used directly!
      SetupViewport();
      Application.Idle += Application_Idle; // press TAB twice after +=
      sw.Start(); // start at application boot
    }

    void Application_Idle(object sender, EventArgs e)
    {
      double milliseconds = ComputeTimeSlice();
      Accumulate(milliseconds);
      Animate(milliseconds);
    }

    float rotation = 0;
    private void Animate(double milliseconds)
    {
      float deltaRotation = (float)milliseconds / 20.0f;
      rotation += deltaRotation;
      glControl1.Invalidate();
    }

    double accumulator = 0;
    int idleCounter = 0;
    private void Accumulate(double milliseconds)
    {
      idleCounter++;
      accumulator += milliseconds;
      if (accumulator > 1000)
      {
        label1.Text = idleCounter.ToString();
        accumulator -= 1000;
        idleCounter = 0; // don't forget to reset the counter!
      }
    }

    private double ComputeTimeSlice()
    {
      sw.Stop();
      double timeslice = sw.Elapsed.TotalMilliseconds;
      sw.Reset();
      sw.Start();
      return timeslice;
    }

    private void SetupViewport()
    {
      int w = glControl1.Width;
      int h = glControl1.Height;
      GL.MatrixMode(MatrixMode.Projection);
      GL.LoadIdentity();
      GL.Ortho(0, w, 0, h, -1, 1); // Bottom-left corner pixel has coordinate (0, 0)
      GL.Viewport(0, 0, w, h); // Use all of the glControl painting area
    }

    private void glControl1_Paint(object sender, PaintEventArgs e)
    {
      if (!loaded)
        return;

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

      GL.MatrixMode(MatrixMode.Modelview);
      GL.LoadIdentity();

      GL.Translate(x, 0, 0);

      if (glControl1.Focused)
        GL.Color3(Color.Yellow);
      else
        GL.Color3(Color.Blue);
      GL.Rotate(rotation, Vector3.UnitZ); // OpenTK has this nice Vector3 class!
      GL.Begin(BeginMode.Triangles);
      GL.Vertex2(10, 20);
      GL.Vertex2(100, 20);
      GL.Vertex2(100, 50);
      GL.End();

      glControl1.SwapBuffers();
    }

    int x = 0;
    private void glControl1_KeyDown(object sender, KeyEventArgs e)
    {
      if (e.KeyCode == Keys.Space)
      {
        x++;
        glControl1.Invalidate();
      }
    }

    private void glControl1_Resize(object sender, EventArgs e)
    {
      SetupViewport();
      glControl1.Invalidate();
    }
  }
}

why gl.vector3 doesn't work?

2 Answers2