File:Ледовый многоугольник.png

uses GraphABC; 
const
  N = 4;
  R = 300;
  Inside = true;
  K = 0.5;

procedure RLine(x, y, x1, y1: real):=Line(Round(x), Round(y), Round(x1), Round(y1)); 

procedure Draw(x, y, r, angle: real);
begin
  var angle1 := DegToRad(angle);
  var angle2 := DegToRad(angle - 90);
  
  var x2 := x + r * Cos(angle1); 
  var y2 := y + r * Sin(angle1); 
  var mx := (x + x2) / 2; 
  var my := (y + y2) / 2;
  var r2 := r / 2;
  var r3 := r2 * K;
  var cx := mx + r3 * Cos(angle2);
  var cy := my + r3 * Sin(angle2);
  
  RLine(x, y, x2, y2); 
  RLine(mx, my, cx, cy);
  
  if r > 20 then 
  begin
    Draw(x, y, r2, angle); 
    Draw(mx, my, r2, angle); 
    Draw(mx, my, r3, angle - 90); 
    Draw(cx, cy, r3, angle + 90); 
  end; 
end;

function GetAngle(x, y, x2, y2: real): real;
begin
  var angle := Abs(RadToDeg(ArcTan((y2 - y) / (x2 - x))));
  if (x2 = x) and (y2 = y) then
    Result := 0
  else
    if x2 > x then
      if y2 > y then Result := angle else Result := 360 - angle
    else
      if y2 > y then Result := 180 - angle else Result := 180 + angle;
end;

procedure DrawIce(x, y, x1, y1: real):=Draw(x, y, sqrt(Sqr(x1 - x) + Sqr(y1 - y)), GetAngle(x, y, x1, y1));

begin
  FloodFill(1, 1, clBlack); 
  SetPenColor(clCyan); 
  
  var Angle := 360 / N;
  var W := Window.Width;
  var H := Window.Height;
  
  LockDrawing();
  MaximizeWindow();
  for var i := 0 to N - 1 do
  begin
    var ang1 := DegToRad(Angle * i);
    var ang2 := DegToRad(Angle * (i + 1));
    if not Inside then
      DrawIce(W + R * Cos(ang1), H + R * Sin(ang1), W + R * Cos(ang2), H + R * Sin(ang2))
    else
      DrawIce(W + R * Cos(ang2), H + R * Sin(ang2), W + R * Cos(ang1), H + R * Sin(ang1));
  end;
  Redraw();
end.