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unit mainform;
{$mode objfpc}{$H+}
interface
uses
Classes, Forms, ExtCtrls, StdCtrls, ComCtrls;
type
{ TForm1 }
TForm1 = class(TForm)
Label1: TLabel;
timerRedraw: TTimer;
trackSpeed: TTrackBar;
procedure FormPaint(Sender: TObject);
procedure timerRedrawTimer(Sender: TObject);
procedure trackSpeedChange(Sender: TObject);
private
public
CurStep: Double;
procedure RotatePolygon(var APoints: array of TPoint; AAngle: Double);
function RotatePoint(APoint, ACenter: TPoint; AAngle: Double): TPoint;
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
uses
Math;
{ TForm1 }
procedure TForm1.timerRedrawTimer(Sender: TObject);
begin
CurStep := CurStep + 0.1;
if CurStep > 360 then CurStep := 0;
Form1.Invalidate;
end;
procedure TForm1.trackSpeedChange(Sender: TObject);
begin
timerRedraw.Interval := 1000 div trackSpeed.Position;
end;
procedure TForm1.RotatePolygon(var APoints: array of TPoint; AAngle: Double);
var
lCenter: TPoint;
i: Integer;
begin
lCenter := Point(0, 0);
for i := 0 to Length(APoints)-1 do
begin
lCenter.X := lCenter.X + APoints[i].X;
lCenter.Y := lCenter.Y + APoints[i].Y;
end;
lCenter.X := lCenter.X div Length(APoints);
lCenter.Y := lCenter.Y div Length(APoints);
for i := 0 to Length(APoints)-1 do
APoints[i] := RotatePoint(APoints[i], lCenter, AAngle);
end;
function TForm1.RotatePoint(APoint, ACenter: TPoint; AAngle: Double): TPoint;
var
dx, dy: Double;
sinAngle, cosAngle: Double;
begin
SinCos(AAngle, sinAngle, cosAngle);
dx := ACenter.Y * sinAngle - ACenter.X * cosAngle + ACenter.X + 10;
dy := -ACenter.X * sinAngle - ACenter.Y * cosAngle + ACenter.Y + Height div 4;
Result.X := Round(APoint.X * cosAngle - APoint.Y * sinAngle + dx);
Result.Y := Round(APoint.X * sinAngle + APoint.Y * cosAngle + dy);
end;
procedure TForm1.FormPaint(Sender: TObject);
var
lPoints: array[0..2] of TPoint;
begin
lPoints[0].X := Self.Width div 4;
lPoints[0].Y := Self.Height div 4;
lPoints[1].X := Self.Width div 2;
lPoints[1].Y := 0;
lPoints[2].X := Self.Width div 2;
lPoints[2].Y := Self.Height div 2;
RotatePolygon(lPoints, CurStep);
Canvas.Polygon(lPoints);
end;
end.
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