int y = Screen.PrimaryScreen.Bounds.Height - this.PreferredSize.Height;
        glControl1.Location = new Point(0, y/2);
    private void OpenGL_SizeChanged(object sender, EventArgs e)
    {
        glControl1.Width = this.Width;
        glControl1.Height = this.Height/2;
    }

  private void CreateShaders()
    {
        /***********Vert Shader********************/
        vertShader = GL.CreateShader(ShaderType.VertexShader);
        GL.ShaderSource(vertShader, @"attribute vec3 a_position;
                                varying vec2 vTexCoordIn;
                         //uniform float aspect;
     void main() {
       vTexCoordIn=( a_position.xy+1)/2;
      gl_Position = vec4(a_position,1);
      }");
        GL.CompileShader(vertShader);

        /***********Frag Shader ****************/
        fragShader = GL.CreateShader(ShaderType.FragmentShader);
        GL.ShaderSource(fragShader, @"
uniform sampler2D sTexture;
uniform sampler2D sTexture1;
uniform sampler2D sTexture2;

uniform vec2 sTexSize;
uniform vec2 sTexSize1;
uniform vec2 sTexSize2;
varying vec2 vTexCoordIn;
void main ()
{
vec2 vTexCoord=vec2(vTexCoordIn.x,vTexCoordIn.y);
if ( vTexCoord.x < 1.0/3.0 )
{
    vec2 uv = vec2(vTexCoord.x * 3.0, vTexCoord.y);
    uv.y *= sTexSize.x / sTexSize.y;
    if (uv.y > 1.0)
    discard;
    else
    gl_FragColor = texture2D(sTexture, uv);
}
else if ( vTexCoord.x >= 1.0/3.0 && vTexCoord.x < 2.0/3.0 )
{
 vec2 uv = vec2(vTexCoord.x * 3.0 - 1.0, vTexCoord.y);
 uv.y *= sTexSize1.x / sTexSize1.y;
 if (uv.y > 1.0)
 discard;
 else
 gl_FragColor = texture2D(sTexture1, uv);
}
else if ( vTexCoord.x >= 2.0/3.0 )
{
  vec2 uv = vec2(vTexCoord.x * 3.0 - 2.0, vTexCoord.y);
  uv.y *= sTexSize2.x / sTexSize2.y;
  if (uv.y > 1.0)
  discard;
  else
  gl_FragColor = texture2D(sTexture2, uv);
 }
   }");
  GL.CompileShader(fragShader);
    }