//
//+----------------------------------------------------------------------+
//+ Program DISKS.CPP                                                    +
//+ By Fausto A. A. Barbuto, BJ06@C53000.PETROBRAS.ANRJ.BR               +
//+ Rio de Janeiro, BRAZIL, on May 14, 1994.                             +
//+                                                                      +
//+ Plots six Julia sets with inner contours in shadings of gray.        +
//+                                                                      +
//+ REFERENCE: Peitgen, H.-O. & Richter, P.H.: "The Beauty of Fractals", +
//+            Springer-Verlag, 1986.                                    +
//+                                                                      +
//+ Needs SVGA256.BGI and SVGA256.H (from SVGABG50 package by Jordan     +
//+ Hargrave).                                                           +
//+                                                                      +
//+ Authorized version for spanky.triumf.ca site (Vancouver, BC, CANADA).+
//+----------------------------------------------------------------------+
//
#include <stdio.h>
#include <conio.h>
#include <graphics.h>
#include <math.h>
#include "Svga256.h"
//void far initgraph(int far *,int far *,char far *);

int Vid;  //Global variable

int huge DetectSVGA256()
{
  printf("\n Which video mode would you like to use? \n\n");
  printf(" 0 - 320x200x256\n");
  printf(" 1 - 640x400x256\n");
  printf(" 2 - 640x480x256\n");
  printf(" 3 - 800x600x256\n");
  printf(" 4 - 1024x768x256\n\n");
  printf(" (Try mode 4, if possible) \n\n > ");
  scanf("%d",&Vid);
  return Vid;
}

void main(void)
{
      double xmin, xmax, ymin, ymax, x, y, x0, y0, R1, I1, Temp;
      double deltax, deltay, p, q, r, a, b;
      double c1[6] = {15.0,18.0,15.0,15.0,18.0,15.0};
      double c2[6] = {1.25e+7,13.0,1.5e+3,38.0,125.0,75.0};
      register int npix, npiy, k, np, nq;
      int Maxit, ipen, index;
      int graphdriver=DETECT, graphmode;

      printf("\n  Program DISKS.CPP \n");
      printf("\n\n  By Fausto A. A. Barbuto, May 14, 1994");
      printf("\n  Rio de Janeiro, Federal Republic of Brazil");
      printf("\n  E-mail: BJ06@C53000.PETROBRAS.ANRJ.BR\n\n");
      printf("\n  Reference: Peitgen, H.-O., and Richter, P.H. :");
      printf("\n  'The Beauty of Fractals', Springer-Verlag, 1986\n\n");
      printf("\n                   Select a Julia set: \n\n");
      printf("   1: c = -0.123750 + 0.565080i  (Map 20, pg. 52) \n");
      printf("   2: c = -0.390540 - 0.586790i  (Map 22 & 25, pgs. 52, 77)\n");
      printf("   3: c =  0.310000 + 0.040000i  (Hmmm... Pretty good!)\n");
      printf("   4: c = -0.481762 - 0.531657i   \n");
      printf("   5: c =  0.273340 + 0.007420i  (Fausto's favourite)\n");
      printf("   6: c = -0.125000 + 0.649250i   \n");
      printf("\n> ");
      scanf("%d",&index);
      if ((index<1) || (index>6)) index = 1;

      if (index == 1) {xmin=-1.40;xmax=1.40;ymin=-1.4;ymax=1.4;Maxit=128;
		       p=-0.123750;q= 0.565080;}
      if (index == 2) {xmin=-1.50;xmax=1.50;ymin=-1.5;ymax=1.5;Maxit=256;
		       p=-0.390540;q=-0.586579;}
      if (index == 3) {xmin=-1.20;xmax=1.20;ymin=-1.2;ymax=1.2;Maxit=256;
		       p= 0.310000;q= 0.040000;}
      if (index == 4) {xmin=-1.50;xmax=1.50;ymin=-1.5;ymax=1.5;Maxit=512;
		       p=-0.481762;q=-0.531657;}
      if (index == 5) {xmin=-1.10;xmax=1.10;ymin=-1.1;ymax=1.1;Maxit=256;
		       p= 0.273340;q= 0.007420;}
      if (index == 6) {xmin=-1.75;xmax=1.75;ymin=-1.5;ymax=1.5;Maxit=512;
		       p=-0.125000;q= 0.649250;}
      clrscr();

      installuserdriver("Svga256",DetectSVGA256);
      initgraph(&graphdriver, &graphmode, "c:\\borlandc\\bgi");
      if (Vid == 0) {npix = 320; npiy = 200;}
      if (Vid == 1) {npix = 640; npiy = 400;}
      if (Vid == 2) {npix = 640; npiy = 480;}
      if (Vid == 3) {npix = 800; npiy = 600;}
      if (Vid == 4) {npix =1024; npiy = 768;}
      if((Vid<0) || (Vid)>4) Vid = 2;

      deltax = (xmax-xmin)/(npix-1);
      deltay = (ymax-ymin)/(npiy-1);

      cleardevice();
      for (np=0; np<=npix-1; np++) {
	x0 = xmin + (double)np*deltax;
	for (nq=0; nq<=npiy-1; nq++) {
	y0 = ymin + (double)nq*deltay;
	x = x0;
	y = y0;
	k  = 0;

	 do {
	   Temp = x*y;
	   R1 = (x-y)*(x+y) + p;
	   I1 = Temp + Temp + q;
	   r = sqrt(R1*R1 + I1*I1);
	   k++;

	   if (r >= Maxit) {   //* Escaped points. *//
	     ipen = 30 + k;
	     putpixel(np,nq,ipen);
	   }

	   if (k == Maxit) {   //* Converged points. *//
//*
//*          The colour shades of the inner contours are defined here
//*          (as function of the distance between the current point [x,y]
//*          and an "invariant" point [x=R(z),y=I(z)]).
//*
	     a = (x-R1)*(x-R1);
	     b = (y-I1)*(y-I1);
	     ipen = c1[index-1] + (int)(c2[index-1]*sqrt(a+b));
	     putpixel(np,nq,ipen);
	   }

	   x = R1;
	   y = I1;
	 } while (r <= Maxit && k<=Maxit);
       }
       if(kbhit()) break;
     }

     getch();
     closegraph();
}