VBO: Triangle + Shader + Uniform

using System;
using System.Drawing;
using OpenTK;
using OpenTK.Graphics;
using OpenTK.Graphics.OpenGL;
 
namespace OpenTKUniformVariables
{
	class Program : GameWindow
	{
		string vertexShaderSource = @"
#version 330
 
layout (location = 0) in vec3 Position;
 
uniform float scale;
 
void main()
{
	gl_Position = vec4(scale * Position.x,
	                   scale * Position.y,
	                   Position.z, 1.0);
}";
 
		string fragmentShaderSource = @"
#version 330
 
out vec4 FragColor;
 
void main()
{
	FragColor = vec4(0.5, 0.8, 1.0, 1.0);
}";
 
 
		int vbo, 
			shaderProgramHandle, vertexShaderHandle, fragmentShaderHandle;
 
		int uniformScale;
		float variableScale;
 
		double time;
 
		void CreateVertexBuffer()
		{
			Vector3[] vertices = new Vector3[3];
			vertices[0] = new Vector3(-1f, -1f, 0f);
			vertices[1] = new Vector3( 1f, -1f, 0f);
			vertices[2] = new Vector3( 0f,  1f, 0f);
 
			GL.GenBuffers(1, out vbo);
			GL.BindBuffer(BufferTarget.ArrayBuffer, vbo);
			GL.BufferData<Vector3>(BufferTarget.ArrayBuffer,
			                       new IntPtr(vertices.Length * Vector3.SizeInBytes),
			                       vertices, BufferUsageHint.StaticDraw);
		}
 
		void CreateShaders()
		{
			shaderProgramHandle = GL.CreateProgram();
 
			vertexShaderHandle = GL.CreateShader(ShaderType.VertexShader);
			fragmentShaderHandle = GL.CreateShader(ShaderType.FragmentShader);
 
			GL.ShaderSource(vertexShaderHandle, vertexShaderSource);
			GL.ShaderSource(fragmentShaderHandle, fragmentShaderSource);
 
			GL.CompileShader(vertexShaderHandle);
			GL.CompileShader(fragmentShaderHandle);
			Console.WriteLine(GL.GetShaderInfoLog(vertexShaderHandle));
			Console.WriteLine(GL.GetShaderInfoLog(fragmentShaderHandle));
 
			GL.AttachShader(shaderProgramHandle, vertexShaderHandle);
			GL.AttachShader(shaderProgramHandle, fragmentShaderHandle);
			GL.LinkProgram(shaderProgramHandle);
			Console.WriteLine(GL.GetProgramInfoLog(shaderProgramHandle));
			GL.UseProgram(shaderProgramHandle);
 
			uniformScale = GL.GetUniformLocation(shaderProgramHandle, "scale");
		}
 
		protected override void OnLoad(EventArgs e)
		{
			GL.ClearColor(Color.Brown);
			CreateVertexBuffer();
			CreateShaders();
		}
 
		protected override void OnRenderFrame(FrameEventArgs e)
		{
			GL.Clear(ClearBufferMask.ColorBufferBit);
 
			time = (time >= Math.PI) ? 0.0 : time + e.Time;
 
			variableScale = (float)(Math.Sin(time));
			GL.Uniform1(uniformScale, variableScale);
 
			GL.EnableVertexAttribArray(0);
			GL.BindBuffer(BufferTarget.ArrayBuffer, vbo);
			GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, 0, 0);
 
			GL.DrawArrays(BeginMode.Triangles, 0, 3);
 
			GL.DisableVertexAttribArray(0);
 
			SwapBuffers();
		}
 
		public static void Main()
		{
			using (Program p = new Program())
			{
				p.Run(60);
			}
		}
	}
}