procedure TfmMain.Draw2D;
var
  i : integer;
const
  W=512; H= 512;
begin
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  glLoadIdentity;

  glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);


  glBindTexture(GL_TEXTURE_2D, BackTex);
  glColor3ub($FF, $CC, $CC);
  glBegin(GL_QUADS);
    {glTexCoord2f(0.0,0.0);} glVertex2f(0, 0);
    {glTexCoord2f(0.0,1.0);} glVertex2f(0, H);
    {glTexCoord2f(1.0,1.0);} glVertex2f(W, H);
    {glTexCoord2f(1.0,0.0);} glVertex2f(W, 0);
  glEnd();


	// Draw the line segments
  glColor3ub($CC, $FF, $FF); 
  glBegin(GL_LINE_STRIP);
  for i := Low(Points) to High(Points) do
    glVertex3f(Points[i].X, Points[i].Y,0.1);
  glEnd();

	// Draw the interpolated points second.
  glColor3ub($FF, $FF, $CC);			
  glBegin(GL_POINTS);
  for i := Low(Points) to High(Points) do
    glVertex3f(Points[i].X, Points[i].Y,0.2);
  glEnd();

  glFlush();

  SwapBuffers(wglGetCurrentDC);
end;