/**************************************************************
*                   BEAUTY  OF  CHAOS                         *
* ----------------------------------------------------------- *
*   The two scientists Gumowski and Mira proposed in their    *
* publications the following iterative model:                 *
*                                                             *
*           x n+1 = b.y n + F(x n)                            *
*           y n+1 =  -x n + F(x n+1)                          *
*                                                             *
*     with  F(x)  = a.x + (2(1-a)x²)/(1+x²)                   *
*                                                             *
*   According to the value of parameters a and b, and the     *
* coordinates of the starting point, the achieved drawing can *
* have a surprising beauty.                                   *
* ----------------------------------------------------------- *
* Some interesting combinations:                              *
* a=0.1 b=0.99 x0=3 yy0=0 iter=30000 f1=-8 f2=8 f3=-6 f4=6    *
* a=0.01 b=0.96 x0=5 yy0=0 iter=25000 f1=-12 f2=12 f3=-8 f4=8 *
* a=0.32 b=1 x0=-5 yy0=0 iter=30000 f1=-16 f2=16 f3=-12 f4=12 *
* a=0.31 b=1 x0=12 yy0=0 iter=30000 f1=-40 f2=40 f3=-25 f4=25 *
* Can you find other ones ?                                   *
* ----------------------------------------------------------- *
* From "Graphisme dans le plan et dans l'espace avec Turbo    *
*       Pascal 4.0 de R. Dony - MASSON 1990, page 198"        *
*       [BIBLI 12].                                           *
*                                                             *
*                    Visual C++ version by J-P Moreau, Paris  *
*                               (www.jpmoreau.fr)             *
*                                                             *
* Uses: Mira.mak, Gr2d.cpp                                    *
**************************************************************/
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

HDC  hdc;
RECT rect;


//Functions used here of module Gr2D.cpp
void Fenetre(double,double,double,double); 
void Cloture(int,int,int,int); 
void Bordure();
void PleinEcran();
void MoveXY(double,double);
void LineXY(double,double);

//"home made" graphic commands for hdc environment used by above functions
void DrawPixel(int ix,int iy) {
  //sorry, no other available command found
  Rectangle(hdc,rect.left+ix,rect.top+iy,
	            rect.left+ix+2,rect.top+iy+1);
}

void Swap(int *i1,int *i2) {
  int it;
  it=*i1; *i1=*i2; *i2=it;
}

void DrawLine(int ix1,int iyy1,int ix2,int iy2) {
  int i,il,ix,iy;
  double dx,dy;
  if (ix2<ix1) {
	Swap(&ix1,&ix2); Swap(&iyy1,&iy2);
  }
  il=(int) sqrt((ix2-ix1)*(ix2-ix1)+(iy2-iyy1)*(iy2-iyy1));
  dx=(double) (ix2-ix1)/il; 
  dy=(double) (iy2-iyy1)/il;
  ix=ix1; iy=iyy1;
  for (i=1;i<il+1; i++) {
	DrawPixel(ix,iy);
	ix=(int) (ix1+i*dx); 
	iy=(int) (iyy1+i*dy);
  }
}

void OutText(int ix,int iy,char *s) {
  RECT rct;
  rct.left=ix; rct.right=ix+10*strlen(s);
  rct.top=iy-5; rct.bottom=iy+15;
  DrawText(hdc, s, -1, &rct,
                DT_SINGLELINE | DT_CENTER | DT_VCENTER);
}

double  a,b,dx,x0,yy0,x1,yy1;
double  f1,f2,f3,f4;
int     n, niter;

extern  MaxX, MaxY;


double F(double x) {
  return (a*x+(1.0-a)*(2.0*x*x/(1.0+x*x)));
}


void Draw_Mira() {
    char s[60];
    //data section (values may be changed by user)
    a=0.31; b=1; x0=12; yy0=0; niter=30000;
    f1=-40; f2=40; f3=-25; f4=25;

    //drawing section

    //client drawing zone in pixels
    MaxX=(rect.right-rect.left);
    MaxY=(rect.bottom-rect.top);

    dx=(f2-f1)/MaxX;
    
    Fenetre(f1,f2,f3,f4);
    Cloture(15,MaxX-15,25,MaxY-15);
    Bordure();

    sprintf(s,"a=%2.2f  b=%2.2f  x0=%3.1f  y0=%3.1f  niter=%d",a,b,x0,yy0,niter);
    OutText(100,MaxY-15,s);

    //main drawing loop
    for (n=1; n<=niter; n++) {
      MoveXY(x0,yy0);
      LineXY(x0+dx,yy0);
      x1=b*yy0 + F(x0);
      yy1=F(x1)- x0;
      x0=x1; yy0=yy1;
    }
} // Draw_Mira()

//Handle Windows Paint and Destroy messages
long FAR PASCAL /*_export*/ WndProc(HWND hwnd,
    UINT message, UINT wParam, LONG lParam) 
{
    HPEN hpen, hpenOld;   
    PAINTSTRUCT ps;

    switch (message) {
        case WM_PAINT:
	    hdc = BeginPaint(hwnd, &ps);
	    GetClientRect(hwnd, &rect);
            hpen = CreatePen(PS_SOLID, 1, RGB(0, 0, 255));
            hpenOld = SelectObject(hdc,hpen);

            Draw_Mira();
               
            SelectObject(hdc,hpenOld);
            DeleteObject(hpen);
            EndPaint(hwnd, &ps);
            return 0;
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}

// main program
int PASCAL WinMain(HANDLE hInstance, HANDLE hPrevInstance,
    LPSTR lpszCmdParam, int nCmdShow)
{
    static char szAppName[] = "Mira";
    HWND        hwnd;
    MSG         msg;
    WNDCLASS    wndclass;

    if (!hPrevInstance) {
        wndclass.style         = CS_HREDRAW | CS_VREDRAW;
        wndclass.lpfnWndProc   = WndProc;
        wndclass.cbClsExtra    = 0;
        wndclass.cbWndExtra    = 0;
        wndclass.hInstance     = hInstance;
        wndclass.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
        wndclass.hCursor       = LoadCursor(NULL, IDC_ARROW);
        wndclass.hbrBackground = GetStockObject(WHITE_BRUSH);
        wndclass.lpszMenuName  = NULL;
        wndclass.lpszClassName = szAppName;

        RegisterClass(&wndclass);
    }

    hwnd = CreateWindow(szAppName,  // window class name
        " MIRA'S CHAOS",            // window caption
        WS_OVERLAPPEDWINDOW,        // window style                       
        CW_USEDEFAULT,              // initial x position
        CW_USEDEFAULT,              // initial y position
        CW_USEDEFAULT,              // initial x size
        CW_USEDEFAULT,              // initial y size
        NULL,                       // parent window handle
        NULL,                       // window menu handle
        hInstance,                  // program instance handle
        NULL);                      // creation parameters

   ShowWindow(hwnd, nCmdShow);
   UpdateWindow(hwnd);

   while (GetMessage(&msg, NULL, 0, 0)) {
       TranslateMessage(&msg);
       DispatchMessage(&msg);
   }
   return msg.wParam;
}

//end of file mira.cpp