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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <complex.h>
#include <unistd.h>
#include <pthread.h>
#include <assert.h>
#include "lodepng.h"
#ifndef CMPLX
#define CMPLX(r,i) ((r) + (i)*I)
#endif
const int MAXITER=200;
const double EPS=1e-1;
static double complex att_func(double complex x,double exponent){
#if 0
static const int N=9;
double complex r=1,y=x;
for(int i=1;i<N;i++){
r+=y;
y*=x;
}
r+=y;
return clog(r);
#else
return clog((1-cpow(x,exponent+1))/(1-x));
#endif
}
struct colour{
unsigned char r,g,b;
};
static struct colour make_colour(double complex z){
static const double N=3;
double norm=cabs(z);
if(norm>N)norm=N;
int clrv=(int)(norm/N*255);
return (struct colour){clrv,clrv,clrv};
}
struct config{
double unitsz;
int width,height;
double exponent;
};
struct thread_info{
pthread_t th;
int ystart,yend;
unsigned char *img;
bool do_basins;
struct config cfg;
};
static void* thread_entry(void *arg_vp){
struct thread_info *th_info=arg_vp;
int ystart=th_info->ystart;
int yend=th_info->yend;
unsigned char *img=th_info->img;
bool do_basins=th_info->do_basins;
struct config cfg=th_info->cfg;
int nbasins=0,bsz=0;
double complex *basins=NULL;
if(do_basins){
bsz=16;
basins=malloc(bsz*sizeof(double complex));
assert(basins);
}
printf("Thread: y in [%d,%d)\n",ystart,yend);
for(int iy=ystart;iy<yend;iy++){
for(int ix=0;ix<cfg.width;ix++){
const double complex start=CMPLX(
(double)(ix-cfg.width/2)/cfg.unitsz,
(double)(iy-cfg.height/2)/cfg.unitsz);
double complex z=start;
for(int i=0;i<MAXITER;i++){
z=att_func(z,cfg.exponent);
}
if(do_basins){
int bi;
for(bi=0;bi<nbasins;bi++){
if(cabs(z-basins[bi])<EPS)break;
}
if(bi==nbasins){
if(nbasins==bsz){
bsz*=2;
basins=realloc(basins,bsz*sizeof(double complex));
assert(basins);
}
fprintf(stderr,"New basin at %lf,%lf (from point %lf,%lf)\n",creal(z),cimag(z),creal(start),cimag(start));
basins[bi]=z;
nbasins++;
}
basins[bi]=(basins[bi]+z)/2;
// struct colour clr=make_colour(bi);
}
struct colour clr=make_colour(z);
img[3*(iy*cfg.width+ix)+0]=clr.r;
img[3*(iy*cfg.width+ix)+1]=clr.g;
img[3*(iy*cfg.width+ix)+2]=clr.b;
}
}
pthread_exit(NULL);
}
int main(int argc,char **argv){
struct config cfg={
.unitsz=200,
.width=500, .height=500,
.exponent=8.5
};
if(argc>=2){
cfg.exponent=strtod(argv[1],NULL);
}
const char *fname;
if(argc>=3){
fname=argv[2];
} else {
fname="out.png";
}
unsigned char img[cfg.width*cfg.height*3];
int nthreads=sysconf(_SC_NPROCESSORS_ONLN);
if(nthreads==4)nthreads/=2;
if(nthreads>=999||nthreads<1)nthreads=1;
fprintf(stderr,"Using %d thread%s\n",nthreads,nthreads==1?"":"s");
pthread_attr_t attr;
if(pthread_attr_init(&attr)!=0){
perror("pthread_attr_init");
return 1;
}
struct thread_info ths[nthreads];
for(int i=0;i<nthreads;i++){
ths[i].ystart=i*cfg.height/nthreads;
ths[i].yend=(i+1)*cfg.height/nthreads;
ths[i].img=img;
ths[i].do_basins=nthreads==1;
ths[i].cfg=cfg;
int ret=pthread_create(&ths[i].th,&attr,thread_entry,&ths[i]);
if(ret!=0){
perror("pthread_create");
return 1;
}
}
pthread_attr_destroy(&attr);
for(int i=0;i<nthreads;i++){
int ret=pthread_join(ths[i].th,NULL);
if(ret!=0){
perror("pthread_join");
return 1;
}
}
lodepng_encode_file(fname,img,cfg.width,cfg.height,LCT_RGB,8);
}
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