Движение по синусоиде

//---------------------------------------------------------------------------
 
#include <vcl.h>
#include "math.h"
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
int d=2; //скорость вращения
int n=0;//счётчик
int xx=100;
int yy=300;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
  DoubleBuffered = 1;
  Timer1->Interval = 30;
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::Timer1Timer(TObject *Sender) //вращение прямоугольника
{
  Refresh();
  static double angle = 0;
  rectangle(Canvas, clBlack, clPurple, 100, 300, 400, 100, angle++);
}
//---------------------------------------------------------------------------
 
 
void TForm1::rectangle(TCanvas * canvas, TColor pen_color, TColor brush_color, int x1, int y1, int x2, int y2, double angle)
{
  angle *= M_PI/180;
  canvas->Pen->Color = pen_color;
  canvas->Brush->Color = brush_color;
  int half_difx = abs(x2-x1)/2, half_dify = abs(y2-y1)/2, r = sqrt(half_difx * half_difx + half_dify * half_dify);
  int minx = x1 < x2 ? x1 : x2, miny = y1 < y2 ? y1 : y2;
  TPoint center = TPoint(minx+half_difx, miny+half_dify);
  double angle2 = atan(1.*half_dify / half_difx);
  canvas->MoveTo(center.x - r*cos(angle2 + angle), center.y + r*sin(angle2 + angle));
  canvas->LineTo(center.x + r*cos(angle2 - angle), center.y + r*sin(angle2 - angle));
  canvas->LineTo(center.x + r*cos(angle2 + angle), center.y - r*sin(angle2 + angle));
  canvas->LineTo(center.x - r*cos(angle2 - angle), center.y - r*sin(angle2 - angle));
  canvas->LineTo(center.x - r*cos(angle2 + angle), center.y + r*sin(angle2 + angle));
  canvas->FloodFill(center.x, center.y, canvas->Pixels[center.x][center.y], fsSurface);
}
 
void __fastcall TForm1::Timer2Timer(TObject *Sender) //движение прямоугольника по синусоиде
{
   xx+=d;
   yy = (int)(sin(xx/10)*(Form1->Height/10)+(Form1->Height/2));
   Form1->Timer2->Interval = 40;
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Timer2Timer(TObject *Sender)
{
   xx+=d;
   yy = (int)(sin(xx/10.)*(Form1->Height/10)+(Form1->Height/2)); // Внимательно!!! Там точка добавлена
   Form1->Timer2->Interval = 40;
}
//---------------------------------------------------------------------------
 
void TForm1::rectangle(TCanvas * canvas, TColor pen_color, TColor brush_color, int x1, int y1, int x2, int y2, double angle)
{
  angle *= M_PI/180;
  canvas->Pen->Color = pen_color;
  canvas->Brush->Color = brush_color;
  int half_difx = abs(x2-x1)/2, half_dify = abs(y2-y1)/2, r = sqrt(half_difx * half_difx + half_dify * half_dify);
  int minx = x1 < x2 ? x1 : x2, miny = y1 < y2 ? y1 : y2;
  TPoint center = TPoint(minx+half_difx, miny+half_dify);
  double angle2 = atan(1.*half_dify / half_difx);
  canvas->MoveTo((xx-100)+center.x - r*cos(angle2 + angle), yy/*center.y*/ + r*sin(angle2 + angle));
  canvas->LineTo((xx-100)+center.x + r*cos(angle2 - angle), yy/*center.y*/ + r*sin(angle2 - angle));
  canvas->LineTo((xx-100)+center.x + r*cos(angle2 + angle), yy/*center.y*/ - r*sin(angle2 + angle));
  canvas->LineTo((xx-100)+center.x - r*cos(angle2 - angle), yy/*center.y*/ - r*sin(angle2 - angle));
  canvas->LineTo((xx-100)+center.x - r*cos(angle2 + angle), yy/*center.y*/ + r*sin(angle2 + angle));
  canvas->FloodFill((xx-100)+center.x, yy/*center.y*/, canvas->Pixels[(xx-100)+center.x][yy/*center.y*/], fsSurface);
}

// новая функция
void rectangle2(TCanvas *canvas, TColor pen_color, TColor brush_color, TPoint center, int width, int height, double angle)
{
  angle *= M_PI/180;
  canvas->Pen->Color = pen_color;
  canvas->Brush->Color = brush_color;
  int r = sqrt(width * width / 4 + height * height / 4);
  double angle2 = atan(1.*height / width);
  canvas->MoveTo(center.x - r*cos(angle2 + angle), center.y + r*sin(angle2 + angle));
  canvas->LineTo(center.x + r*cos(angle2 - angle), center.y + r*sin(angle2 - angle));
  canvas->LineTo(center.x + r*cos(angle2 + angle), center.y - r*sin(angle2 + angle));
  canvas->LineTo(center.x - r*cos(angle2 - angle), center.y - r*sin(angle2 - angle));
  canvas->LineTo(center.x - r*cos(angle2 + angle), center.y + r*sin(angle2 + angle));
  canvas->FloodFill(center.x, center.y, canvas->Pixels[center.x][center.y], fsSurface);
}

void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
  Refresh();
  static double angle = 0, x = 250, y = 200, radius = 15, period = 2.5;
//  rectangle(Canvas, clBlack, clBlue, 100, 300, 400, 100, angle++);  // вращение без перемещения ("старая" функция)
//  rectangle2(Canvas, clBlack, clBlue, TPoint(x, y), 300, 200, angle++);  // такое же вращение без перемещения
//  rectangle2(Canvas, clBlack, clBlue, TPoint(x++, y++), 300, 200, angle++);  // вращение с движением по наклонной линии
  rectangle2(Canvas, clBlack, clBlue, TPoint(x++, y+radius*sin(angle/period)), 300, 200, angle++);  // по синусоиде
//  rectangle2(Canvas, clBlack, clBlue, TPoint(x+radius*cos(angle/period), y+radius*sin(angle/period)), 300, 200, angle++);  // по окружности
}