CONST 
  BarWidth = 0.3 * Unit.In, 
  HoleRad = 0.05 * Unit.In, 
  LineWidth = 1.5, 
  Len1 = 0.75 * Unit.In, 
  Len2 = 1.5 * Unit.In, 
  Len3 = 2 * Unit.In, 
  Len4 = 2.5 * Unit.In;

PRED IsLink1(a, b) IS 
  Geometry.Dist(a, b) = Len1 
END;

UI PointTool(IsLink1);

PRED IsLink2(a, b) IS 
  Geometry.Dist(a, b) = Len2 
END;

UI PointTool(IsLink2);

PRED IsLink3(a, b) IS 
  Geometry.Dist(a, b) = Len3 
END;

UI PointTool(IsLink3);

PRED IsLink4(a, b) IS 
  Geometry.Dist(a, b) = Len4 
END;

UI PointTool(IsLink4);

PRIVATE PROC DrawHole(a) IS 
  VAR b IN 
    b := R2.Plus(a, (HoleRad, 0)); 
    Circle.DrawCC(a, b) 
  END 
END;

UI PointTool(DrawHole);

PRIVATE PROC FillBody() IS 
  SAVE PS IN 
    PS.SetColor(Color.Grey50); PS.Fill() 
  END; 
  PS.SetWidth(LineWidth); 
  PS.Stroke() 
END;

UI PointTool(FillBody);

PROC DrawLink(a, b) IS 
  IF 
    VAR 
      c ~ (1, 0.08052) REL (a, b), 
      d = Geometry.Mid(a, b), 
      e ~ (1, 0.08052) REL (b, a) 
    IN 
      Angle.Right(a, b, c) AND 
      BarWidth = 2 * Geometry.Dist(b, c) AND 
      d = Geometry.Mid(c, e) -> 
        PS.MoveTo(c); 
        Circle.DrawQuarter(b); 
        Circle.DrawQuarter(b); 
        PS.LineTo(e); 
        Circle.DrawQuarter(a); 
        Circle.DrawQuarter(a); 
        PS.Close(); 
        DrawHole(a); 
        DrawHole(b); 
        FillBody() 
    END 
  FI 
END;

UI PointTool(DrawLink);

PROC LabelLink(a, b, txt) IS 
  VAR c IN 
    c := Geometry.Mid(a, b); 
    TypeLinesC.Center(c, txt) 
  END 
END;

UI TextTool(LabelLink);

PROC DrawTriBody(a, b, c) IS 
  IF 
    VAR 
      d ~ (1, 0.12) REL (a, c), 
      e ~ (0, 0.2) REL (c, b), 
      f ~ (1, 0.2) REL (c, b), 
      g ~ (0, 0.138) REL (b, a), 
      h ~ (1, 0.1333) REL (b, a), 
      i ~ (0, 0.2805) REL (a, c) 
    IN 
      Angle.Right(a, c, d) AND 
      Angle.Right(c, a, i) AND 
      Angle.Right(b, c, e) AND 
      Angle.Right(c, b, f) AND 
      Angle.Right(a, b, g) AND 
      Angle.Right(b, a, h) AND 
      BarWidth = 2 * Geometry.Dist(c, d) AND 
      (c, d) CONG (a, h) AND 
      (c, d) CONG (b, f) -> 
        PS.MoveTo(d); 
        Arc.Draw(c, e); 
        PS.LineTo(f); 
        Arc.Draw(b, g); 
        PS.LineTo(h); 
        Arc.Draw(a, i); 
        PS.Close(); 
        DrawHole(c); 
        DrawHole(b); 
        DrawHole(a); 
        FillBody() 
    END 
  FI 
END;

UI PointTool(DrawTriBody);

PROC LabelTriBody(a, b, c, txt) IS 
  VAR d IN 
    d := Triangle.InCenter(a, b, c); 
    TypeLinesC.Center(d, txt) 
  END 
END;

UI TextTool(LabelTriBody);

PROC BrunkhartFig17() IS 
  IF 
    VAR 
      a = (-23.48, 8.343), 
      b = (-91.64, 69.02), 
      c = (75.74, -33.37), 
      d ~ (-36.46, 161.9), 
      e ~ (-23.16, 62.34), 
      f ~ (64.97, 124.8), 
      g ~ (84.18, 74.3), 
      h = (-21.96, 264) 
    IN 
      IsLink1(a, e) AND 
      IsLink2(c, g) AND 
      IsLink2(d, f) AND 
      IsLink2(b, d) AND 
      IsLink2(g, e) AND 
      IsLink2(e, f) AND 
      IsLink1(f, g) AND 
      Geometry.Colinear(a, e, h) -> 
        PS.SetFontSize(PS.Small); 
        PS.SetFontFace("Times-Bold"); 
        DrawLink(a, e); 
        LabelLink(a, e, "I"); 
        DrawLink(c, g); 
        LabelLink(c, g, "III"); 
        DrawTriBody(e, g, f); 
        LabelTriBody(e, g, f, "II"); 
        DrawLink(b, d); 
        LabelLink(b, d, "V"); 
        DrawLink(d, f); 
        LabelLink(d, f, "IV") 
    END 
  FI 
END;

UI Template(BrunkhartFig17);

PROC FourBarLinkage() IS 
  IF 
    VAR 
      a = (-90.89, 56.63), 
      b ~ (-86.75, 110.5), 
      c ~ (20.06, 126.5), 
      d = (45.44, -15.28) 
    IN 
      IsLink1(a, b) AND 
      IsLink2(b, c) AND 
      IsLink3(c, d) -> 
        DrawLink(a, b); 
        DrawLink(b, c); 
        DrawLink(c, d) 
    END 
  FI 
END;

UI Template(FourBarLinkage);

PROC Cmd0() IS 
  IF 
    VAR 
      a = (-90.89, 56.63), b ~ (-61.2, 101.7), c ~ (43.38, 128.7), 
      d = (45.44, -15.28) 
    IN 
      IsLink1(a, b) AND IsLink2(b, c) AND IsLink3(c, d) -> 
        DrawLink(a, b); DrawLink(b, c); DrawLink(c, d) 
    END 
  FI 
END;