const
 Sun   = 1;
 Mars  = 2;
 Earth = 3;
 Moon  = 4;

procedure TGLForm.DrawScene;
begin
glInitNames;
glPushName(0);
...
glLoadName(Sun);
glCallList(SunList);
...
glLoadName(Mars);
glCallList(MarsList);
...
end;

function TGLForm.GetSelectBufferHit : Integer;
var
 SelectBuffer : array[0..512] of TGLUInt;
 Viewport     : TGLArrayi4;
 Hits,i       : Integer;
 HitZValue    : TGLUInt;
 Hit          : TGLUInt;
begin
glGetIntegerv(GL_VIEWPORT, @viewport);
glSelectBuffer(512, @SelectBuffer);
glRenderMode(GL_SELECT);
glInitNames;
glPushName(0);
glMatrixMode(GL_PROJECTION);
glPushMatrix;
 glLoadIdentity;
 gluPickMatrix(mx, viewport[3]-my, 1.0, 1.0, viewport);
 gluPerspective(45.0, ClientWidth/ClientHeight, 0.1, 1000);
 DrawScene;
 glMatrixMode(GL_PROJECTION);
glPopMatrix;
Hits := glRenderMode(GL_RENDER);
Hit       := High(TGLUInt);
HitZValue := High(TGLUInt);
for i := 0 to Hits-1 do
 if SelectBuffer[(i*4)+1] < HitZValue then
  begin
  Hit       := SelectBuffer[(i*4)+3];
  HitZValue := SelectBuffer[(i*4)+1];
  end;
Result := Hit;
end;