/* Hoppy's animated Juliaset program
 * Displays Julia set and varies the parameters from frame to frame
 * Displays frame rate
 * Quit with key press
/*
#include "allegro.h"
#include <math.h> 

#define XRES 320
#define YRES 200
#define XSIZE 290
#define YSIZE 180
#define ITER 50

volatile int blitflag=0;
volatile int times=0;
volatile int otimes=0;

void blittime() {
    blitflag=1;
}
END_OF_FUNCTION(blittime);

void calltimes() {
   otimes=times;
   times=0;

}
END_OF_FUNCTION(calltimes);

void main() {

   float x0,y0,p,q,xs,ys,xsq,ysq,xmin,xmax,ymin,ymax;   
   int x,y,iter=ITER,s=3;
   int xoff,yoff;
   register unsigned int i;
   long a;
   char *msg;
   BITMAP *temp;
   xmin=-1.5;
   ymin=-1.5;
   xmax=1.5;
   ymax=1.5;

   allegro_init();
   install_keyboard();
   install_timer();
   
   LOCK_VARIABLE(blitflag);
   LOCK_FUNCTION(blittime);
   

   set_gfx_mode(GFX_VGA, XRES, YRES, 0, 0);

   install_int(blittime, 20);
   install_int(calltimes, 1000);
   
   xoff=(XRES-XSIZE)>>1;
   yoff=(YRES-YSIZE)>>1;

   temp=create_bitmap(XSIZE+1,YSIZE+1);

   xs=(xmax-xmin)/XSIZE;
   ys=(ymax-ymin)/YSIZE;
   while (!keypressed()) {
      a++;
      p=1.5-sin(a/26.6)*3;
      q=1.5-cos(a/31.15)*3;
      for (y=0;y<=YSIZE/2;y++) {
         for (x=0;x<=XSIZE;x++) {
            y0=ymax-y*ys;
            x0=xmin+x*xs;
            for (i=1;i<iter && (ysq=y0*y0)+(xsq=x0*x0)<4;i++) {
               y0=q+(x0*y0)+(x0*y0);
               x0=p+xsq-ysq;
            }
            i=(i==ITER) ? 1 : --i%255; 
            _putpixel (temp,x,y,i+1); 
            _putpixel (temp,XSIZE-x,YSIZE-y,i+1); 
         }
      } 
      times++;
      if (blitflag) {
         sprintf(msg,"Frames/sec:%d",otimes);
         textout (screen,font,msg,0,0,128);     
         blit (temp,screen,0,0,xoff,yoff,XSIZE,YSIZE);
         blitflag=0;
      }
      
   }
   set_gfx_mode(GFX_TEXT, 80, 25, 0, 0); 
}