PolygonRotation.cpp

#include <vcl.h>
#pragma hdrstop

#include "PolygonRotate.h"
#include <math.h>
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;

int  X_old;
int  Y_old;

POINT Poly1a[5]  = {{100, 100}, {300, 100}, {300, 300}, {100, 300}, {100,100}};
POINT *pPoly1a   = Poly1a;

POINT Poly1b[5]  = {{500, 100}, {700, 100}, {700, 300}, {500, 300}, {500,100}};
POINT *pPoly1b   = Poly1b;

POINT Poly2a[5];
POINT* pPoly2a = Poly2a;

POINT Poly2b[5];
POINT* pPoly2b = Poly2b;


//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
    Position = poScreenCenter;
    Width = 800;
    Height = 600;
    Color = (TColor)0xabcdef;  // Cream
}
//---------------------------------------------------------------------------

void Translate(POINT* pin, POINT* pout, long DX, long DY)
{
    for (int i = 0; i < 5; i++)
    {
        (pout+i)->x = (pin+i)->x + DX;
        (pout+i)->y = (pin+i)->y + DY;
    }
}

void Rotate(POINT* pin, POINT* pout, float Alpha, long xr, long yr,
            int NumberOfPoints)
{
//Rotate Polygon about a given point P whose coordinates are (xr, yr)

   // Degrees to radians
   float const K = -0.01745329;  // 2*3.141592653/360

    for (int i = 0; i < NumberOfPoints; i++)
    {
        (pout+i)->x = (long)(xr + (((pin+i)->x - xr) * cos(K*Alpha))
                                - (((pin+i)->y - yr) * sin(K*Alpha)));

        (pout+i)->y = (long)(yr + (((pin+i)->x - xr) * sin(K*Alpha))
                                + (((pin+i)->y - yr) * cos(K*Alpha)));
    }
}
//---------------------------------------------------------------------------

void Translate(POINT* pin, POINT* pout, long xt, long yt,
               int NumberOfPoints)
{
//Tanslate Polygon

    for (int i = 0; i< NumberOfPoints; i++)
    {
        (pout+i)->x = (long)((pin+i)->x + xt);

        (pout+i)->y = (long)((pin+i)->y + yt);
    }
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormMouseDown(TObject *Sender, TMouseButton Button,
      TShiftState Shift, int X, int Y)
{
       X_old = X;
       Y_old = Y;
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormMouseMove(TObject *Sender, TShiftState Shift,
      int X, int Y)
{

       if (X_old != X)
       {
           // Convert X mouse movement into polygon rotation
           Rotate(pPoly1a, pPoly2a, X, 200, 200, 5);
           Polygon(Canvas->Handle, pPoly2a, 5);     //Win32 API
       }

       if (Y_old != Y)
       {
           // Convert Y mouse movement into polygon rotation           
           Rotate(pPoly1b, pPoly2b, Y, 600, 200, 5);
           Polygon(Canvas->Handle, pPoly2b, 5);     //Win32 API
       }

       X_old = X;
       Y_old = Y;
}
//---------------------------------------------------------------------------

PolygonRotation.h

#ifndef PolygonRotateH
#define PolygonRotateH
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <ExtCtrls.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:	// IDE-managed Components
        void __fastcall FormMouseDown(TObject *Sender, TMouseButton Button,
          TShiftState Shift, int X, int Y);
        void __fastcall FormMouseMove(TObject *Sender, TShiftState Shift,
          int X, int Y);
private:	// User declarations
public:		// User declarations
        __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif