PresleyDias
Reputation: 3711
openTK c# roatating cube example
i am using C# (visual studio 2008) to develop a slot machine, using OpenTK for using openGL in my project we have done the basic functionality but the we cant get a code to draw a cube that can rotate.
THe cude needs to rotate for some time, but i cant figure out how to do it.
we have tried this Cube
but this we want to draw it on a form
Upvotes: 0
Views: 17361
Answers (2)
jackw11111
Reputation: 1547
Here is an example of a rotating cube in C# using OpenTK:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;
using OpenTK.Input;
// adapted from : dreamstatecoding.blogspot.com
namespace RotatingCube
{
public struct Vertex
{
public const int Size = (4 + 4) * 4; // size of struct in bytes
private readonly Vector4 _position;
private readonly Color4 _color;
public Vertex(Vector4 position, Color4 color)
{
_position = position;
_color = color;
}
}
public sealed class MainWindow : GameWindow
{
private readonly string _title;
private int _width;
private int _height;
private int _program;
private double _time;
private bool _initialized;
private int _vertexArray;
private int _buffer;
private int _verticeCount;
private Matrix4 _model;
private Matrix4 _view;
private Matrix4 _projection;
private float _FOV = 45.0f;
private float _lastTimestamp = Stopwatch.GetTimestamp();
private float _freq = Stopwatch.Frequency;
private float _angle;
public MainWindow()
: base(750, // initial width
500, // initial height
GraphicsMode.Default,
"", // initial title
GameWindowFlags.Default,
DisplayDevice.Default,
3, // OpenGL major version
3, // OpenGL minor version
GraphicsContextFlags.ForwardCompatible)
{
_width = 750;
_height = 500;
_title += "Spinning Cube, OpenGL Version: " + GL.GetString(StringName.Version);
}
protected override void OnLoad(EventArgs e)
{
_model = Matrix4.Identity;
Vertex[] vertices =
{
new Vertex(new Vector4(-0.5f, -0.5f, -0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4( 0.5f, -0.5f, -0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4( 0.5f, 0.5f, -0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4( 0.5f, 0.5f, -0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4(-0.5f, 0.5f, -0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4(-0.5f, -0.5f, -0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4(-0.5f, -0.5f, 0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4( 0.5f, -0.5f, 0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4( 0.5f, 0.5f, 0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4( 0.5f, 0.5f, 0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4(-0.5f, 0.5f, 0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4(-0.5f, -0.5f, 0.5f, 1.0f), Color4.Blue),
new Vertex(new Vector4(-0.5f, 0.5f, 0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4(-0.5f, 0.5f, -0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4(-0.5f, -0.5f, -0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4(-0.5f, -0.5f, -0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4(-0.5f, -0.5f, 0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4(-0.5f, 0.5f, 0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4( 0.5f, 0.5f, 0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4( 0.5f, 0.5f, -0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4( 0.5f, -0.5f, -0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4( 0.5f, -0.5f, -0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4( 0.5f, -0.5f, 0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4( 0.5f, 0.5f, 0.5f, 1.0f), Color4.Red),
new Vertex(new Vector4(-0.5f, -0.5f, -0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4( 0.5f, -0.5f, -0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4( 0.5f, -0.5f, 0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4( 0.5f, -0.5f, 0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4(-0.5f, -0.5f, 0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4(-0.5f, -0.5f, -0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4(-0.5f, 0.5f, -0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4( 0.5f, 0.5f, -0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4( 0.5f, 0.5f, 0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4( 0.5f, 0.5f, 0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4(-0.5f, 0.5f, 0.5f, 1.0f), Color4.Green),
new Vertex(new Vector4(-0.5f, 0.5f, -0.5f, 1.0f), Color4.Green),
};
_verticeCount = vertices.Length;
_vertexArray = GL.GenVertexArray();
_buffer = GL.GenBuffer();
GL.BindVertexArray(_vertexArray);
GL.BindBuffer(BufferTarget.ArrayBuffer, _vertexArray);
// create first buffer: vertex
GL.NamedBufferStorage(
_buffer,
Vertex.Size*vertices.Length, // the size needed by this buffer
vertices, // data to initialize with
BufferStorageFlags.MapWriteBit); // at this point we will only write to the buffer
GL.VertexArrayAttribBinding(_vertexArray, 0, 0);
GL.EnableVertexArrayAttrib(_vertexArray, 0);
GL.VertexArrayAttribFormat(
_vertexArray,
0, // attribute index, from the shader location = 0
4, // size of attribute, vec4
VertexAttribType.Float, // contains floats
false, // does not need to be normalized as it is already, floats ignore this flag anyway
0); // relative offset, first item
GL.VertexArrayAttribBinding(_vertexArray, 1, 0);
GL.EnableVertexArrayAttrib(_vertexArray, 1);
GL.VertexArrayAttribFormat(
_vertexArray,
1, // attribute index, from the shader location = 1
4, // size of attribute, vec4
VertexAttribType.Float, // contains floats
false, // does not need to be normalized as it is already, floats ignore this flag anyway
16); // relative offset after a vec4
// link the vertex array and buffer and provide the stride as size of Vertex
GL.VertexArrayVertexBuffer(_vertexArray, 0, _buffer, IntPtr.Zero, Vertex.Size);
_initialized = true;
CursorVisible = true;
try
{
_program = GL.CreateProgram();
var shaders = new List<int>();
ShaderType type = ShaderType.VertexShader;
var shader = GL.CreateShader(type);
string src = @"#version 330 core
layout (location = 0) in vec4 position;
layout(location = 1) in vec4 color;
out vec4 vs_color;
out vec3 original_normal;
out vec3 transformed_normal;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main(void)
{
gl_Position = projection * view * model * position;
vs_color = color;
original_normal = vec3(color);
mat3 normal_matrix = transpose(inverse(mat3(view * model)));
transformed_normal = normal_matrix * original_normal;
}";
GL.ShaderSource(shader, src);
GL.CompileShader(shader);
var info = GL.GetShaderInfoLog(shader);
if (!string.IsNullOrWhiteSpace(info))
throw new Exception($"CompileShader {type} had errors: {info}");
shaders.Add(shader);
type = ShaderType.FragmentShader;
shader = GL.CreateShader(type);
src = @"#version 330 core
in vec4 vs_color;
in vec3 original_normal;
in vec3 transformed_normal;
out vec4 color;
void main(void)
{
float lighting = abs(dot(transformed_normal, vec3(0,0,-1)));
color = vs_color * lighting;
}";
GL.ShaderSource(shader, src);
GL.CompileShader(shader);
info = GL.GetShaderInfoLog(shader);
if (!string.IsNullOrWhiteSpace(info))
throw new Exception($"CompileShader {type} had errors: {info}");
shaders.Add(shader);
foreach (var shader_ in shaders)
GL.AttachShader(_program, shader_);
GL.LinkProgram(_program);
var info_ = GL.GetProgramInfoLog(_program);
if (!string.IsNullOrWhiteSpace(info_))
throw new Exception($"CompileShaders ProgramLinking had errors: {info}");
foreach (var shader_ in shaders)
{
GL.DetachShader(_program, shader_);
GL.DeleteShader(shader_);
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
throw;
}
GL.Enable(EnableCap.DepthTest);
GL.PolygonMode(MaterialFace.Front, PolygonMode.Fill);
GL.PatchParameter(PatchParameterInt.PatchVertices, 3);
Closed += OnClosed;
}
private void OnClosed(object sender, EventArgs eventArgs)
{
Exit();
}
public override void Exit()
{
Debug.WriteLine("Exit called");
GL.DeleteVertexArray(_vertexArray);
GL.DeleteBuffer(_buffer);
GL.DeleteProgram(_program);
base.Exit();
}
protected override void OnResize(EventArgs e)
{
// Resize the viewport to match the window size.
GL.Viewport(0, 0, Width, Height);
base.OnResize(e);
}
private float[] Matrix4ToArray(Matrix4 matrix)
{
float[] data = new float[16];
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
data[i*4+j] = matrix[i, j];
}
}
return data;
}
private void PrintMatrix(Matrix4 matrix)
{
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
Console.WriteLine(matrix[i,j]);
}
}
}
protected override void OnRenderFrame(FrameEventArgs e)
{
var timeStamp = Stopwatch.GetTimestamp();
_angle += (float)((timeStamp - _lastTimestamp) / (double)_freq);
_lastTimestamp = timeStamp;
GL.ClearColor(0.0f, 0.0f, 0.0f, 1.0f);
// Clear the color buffer.
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
// Bind the VBO
GL.BindBuffer(BufferTarget.ArrayBuffer, _buffer);
// Bind the VAO
GL.BindVertexArray(_vertexArray);
// Use/Bind the program
GL.UseProgram(_program);
_model = Matrix4.CreateFromAxisAngle(new Vector3(1.0f, 0.0f, 1.0f), _angle);
_view = Matrix4.LookAt(new Vector3(0.0f,0.0f,5.0f), new Vector3(0.0f,0.0f,0.0f), Vector3.UnitY);
_projection = Matrix4.CreatePerspectiveFieldOfView((float)Math.PI * (_FOV/180f), _width / (float)_height, 0.2f, 256.0f);
int location = GL.GetUniformLocation(_program, "model");
GL.UniformMatrix4(location, 1, false, Matrix4ToArray(_model));
location = GL.GetUniformLocation(_program, "view");
GL.UniformMatrix4(location, 1, false, Matrix4ToArray(_view));
location = GL.GetUniformLocation(_program, "projection");
GL.UniformMatrix4(location, 1, false, Matrix4ToArray(_projection));
// This draws the triangle.
GL.DrawArrays(PrimitiveType.Triangles, 0, _verticeCount);
// Swap the front/back buffers so what we just rendered to the back buffer is displayed in the window.
Context.SwapBuffers();
base.OnRenderFrame(e);
}
[STAThread]
static void Main()
{
new MainWindow().Run(60);
}
}
}
Result:
Upvotes: 0
Robert Rouhani
Reputation: 14688
OpenTK provides a Windows Forms control called GLControl. It has no built-in main loop, but getting continuous rendering to work on the control isn't that hard if you follow this GLControl tutorial.
Once you have continuous rendering working, you can move over the code to render a cube and it will be continuously rotating on a form.
Upvotes: 3
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