Свет в OpenGL. Не выводится изображение на экран.

  glClearColor(1, 1, 1, 1);
  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
  //================
  glEnable(GL_TEXTURE_2D);
  glEnable(GL_BLEND);
  
  glColor3f(1-LightLevel, 1-LightLevel, 1-LightLevel);
 
  case LightFlag of
    0:  begin
          Inc(DayTime);
          if DayTime = 48 then LightFlag := 1;
        end;
    1:  begin
          LightLevel := LightLevel + 0.005;
          if LightLevel >= 1 then LightFlag := 2;
        end;
    2:  begin
          Dec(DayTime);
          if DayTime = 0 then LightFlag := 3;
        end;
    3:  begin
          LightLevel := LightLevel - 0.005;
          if LightLevel <= 0 then LightFlag := 0;
        end;
  end;      
 
  cX := CameraX div PointSize;
  cY := CameraY div PointSize;
 
  for i := cX to cX + SEE_AREA_X do
    for j := cY to cY + SEE_AREA_Y do begin
      if Matrix[i,j].tGround <> -1 then
        DrawImage(-CameraX + i * PointSize, -CameraY + j * PointSize, PointSize,
        PointSize, GroundLib[Matrix[i,j].tGround]);
    end;
 
  glColor3f(0.7, 0.7, 0.7);
  DrawImage(100, 100, 300, 300, Light);
 
  glDisable(GL_BLEND);
  glDisable(GL_TEXTURE_2D);
  //================
  glColor3f(LightLevel, LightLevel, LightLevel);
  glBegin(GL_LINES);
  for i := 0 to SEE_AREA_X do
    for j := 0 to SEE_AREA_Y do begin
      glVertex2f(i * PointSize, 0);
      glVertex2f(i * PointSize, STANDART_HEIGHT);
      glVertex2f(0, j * PointSize);
      glVertex2f(STANDART_WIDTH, j*PointSize);
    end;
  glEnd;
  //===============
 
  SwapBuffers(MainDC);