MODULE Anim2;

PROC an := New(bg, perm, ephem) IS 
  an := [1, bg, perm, ephem] 
END;

PROC Play(an) IS 
  IF 
    VAR t = 0, t0 = 0, start, dur, bg, perm, ephem IN 
      an = [dur, bg, perm, ephem] -> 
        IF bg # NIL -> APPLY(bg) | SKIP FI; 
        PS.SavePage(); 
        start := Time.Now(); 
        DO 
          t < dur -> 
            PS.RestorePage(); 
            IF 
              perm # NIL -> 
                APPLY(perm, t, t0); PS.SavePage() 
            | SKIP 
            FI; 
            IF 
              ephem # NIL -> APPLY(ephem, t) | SKIP 
            FI; 
            t0, t := t, Time.Now() - start; 
            PS.ShowPage() 
        OD; 
        PS.RestorePage(); 
        IF 
          perm # NIL -> APPLY(perm, t, t0) | SKIP 
        FI; 
        IF ephem # NIL -> APPLY(ephem, t) | SKIP FI 
    END 
  FI 
END;

PRIVATE PROC SeqBg(a1, a2, d1) IS SKIP END;

PROC an := Seq(a1, a2) IS 
  IF 
    VAR 
      d1, bg1, perm1, ephem1, d2, bg2, perm2, ephem2 
    IN 
      a1 = [d1, bg1, perm1, ephem1] AND 
      a2 = [d2, bg2, perm2, ephem2] -> SKIP 
    END 
  FI 
END;

PROC an := Co(a1, a2) IS SKIP END;

PROC an := Scale(a, dur) IS SKIP END;