c# - 为什么 gl.vector3 不起作用？

Question

我想在屏幕上显示一个像素。我在 Vs2010 中使用 openTk。这是我在 Windows 窗体应用程序中的代码：

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();
               }

当我运行我的代码时，我只看到一个蓝屏。我不知道出了什么问题！！！

Answer 1

为了显示任何内容，您需要设置投影转换矩阵。在您的代码中，您没有设置任何内容，这意味着渲染将不知道将您的观点放在哪里。

我建议查看一些使用低级 OpenGL 的基本教程。其中大部分应该适用于您的场景。

Answer 2

看看基于 opentk glcontrol 的应用程序

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();
    }
  }
}