Here a simple example:

uses TeCanvas, TeeGLCanvas;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ComboBox1.Items.Add('OpenGL');
  ComboBox1.Items.Add('GDIPlus');
  ComboBox1.ItemIndex:=0;
  ComboBox1Change(Sender);
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
  case ComboBox1.ItemIndex of
    0: Draw3D1.Canvas:=TGLCanvas.Create;
    1: Draw3D1.Canvas:=TGDIPlusCanvas.Create;
  end;
end;

procedure TForm1.Draw3D1Paint(Sender: TObject; const ARect: TRect);
var c: TCanvas3D;
    tx: array[0..8] of TPoint;
begin
  c:=Draw3D1.Canvas;

  c.Pen.Style := psSolid;
  c.Pen.Color := clBlack;
  c.Pen.Width := 2;
  c.Brush.Color := clLime;
  c.Brush.Style := bsSolid;

  tx[0] := Point(100,200);
  tx[1] := Point(100,500);
  tx[2] := Point(500,500);
  tx[3] := Point(500,100);
  tx[4] := Point(400,100);
  tx[5] := Point(400,400);
  tx[6] := Point(200,400);
  tx[7] := Point(200,200);
  tx[8] := Point(100,200);

  c.PolygonWithZ(tx, 8);
end;