You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
103 lines
3.5 KiB
C
103 lines
3.5 KiB
C
#include "colors.h"
|
|
#include <math.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <stdbool.h>
|
|
|
|
int main(int argc, char **argv) {
|
|
if (argc != 6) {
|
|
fprintf(stderr, "usage: %s width height centerx centery magnification", argv[0]);
|
|
return 1;
|
|
}
|
|
long double eps = 1e-17;
|
|
long double Q1LOG2 = 1.44269504088896340735992468100189213742664595415299;
|
|
long double LOG2 = 0.69314718055994530941723212145817656807550013436026;
|
|
int width = atoi(argv[1]);
|
|
int height = atoi(argv[2]);
|
|
char* image = malloc(width*height*3);
|
|
int x, y;
|
|
long double centerx = strtold(argv[3], NULL);
|
|
long double centery = strtold(argv[4], NULL);
|
|
long double bailout = 128;
|
|
long double logLogBailout = log(log(bailout));
|
|
int foundperiods = 0;
|
|
long double magn = strtold(argv[5], NULL);
|
|
long maxiter = width * sqrt(magn);
|
|
long double x0d = 4 / magn / width;
|
|
long double x2 = -2 / magn + centerx;
|
|
long double y1d = -4 / magn / width;
|
|
long double y2 = 2 / magn * height / width + centery;
|
|
int imgidx = 0;
|
|
for (y = 0; y < height; y++) {
|
|
fprintf(stderr, "\r%f %%", (float)imgidx/(width*height*3)*100);
|
|
for (x = 0; x < width; x++) {
|
|
long double px = x*x0d + x2;
|
|
long double py = y*y1d + y2;
|
|
// no Main bulb or Cardoid check to be faster
|
|
long double zx = px;
|
|
long double zy = py;
|
|
long i;
|
|
// Initial maximum period to detect.
|
|
int check = 3;
|
|
// Maximum period doubles every iterations:
|
|
int whenupdate = 10;
|
|
// Period history registers.
|
|
long double hx = 0;
|
|
long double hy = 0;
|
|
long double xx, yy;
|
|
bool inside = true;
|
|
for (i = 1; i <= maxiter; i++) {
|
|
xx = zx * zx;
|
|
yy = zy * zy;
|
|
if (xx + yy > bailout) {
|
|
inside = false;
|
|
break;
|
|
}
|
|
// iterate
|
|
zy = 2 * zx * zy + py;
|
|
zx = xx - yy + px;
|
|
|
|
// periodicity check
|
|
long double d = zx - hx;
|
|
if (d > 0.0 ? d < eps : d > -eps) {
|
|
d = zy - hy;
|
|
if (d > 0.0 ? d < eps : d > -eps) {
|
|
// Period found.
|
|
foundperiods++;
|
|
break;
|
|
}
|
|
}
|
|
if ((i & check) == 0) {
|
|
if (--whenupdate == 0) {
|
|
whenupdate = 10;
|
|
check <<= 1;
|
|
check++;
|
|
}
|
|
// period = 0;
|
|
hx = zx;
|
|
hy = zy;
|
|
}
|
|
}
|
|
|
|
if (inside) {
|
|
image[imgidx++] = 0;
|
|
image[imgidx++] = 0;
|
|
image[imgidx++] = 0;
|
|
} else {
|
|
long double r = sqrtl(zx*zx + zy*zy);
|
|
long double c = i - 1.28 + (logLogBailout - logl(logl(r))) * Q1LOG2;
|
|
int idx = fmodl((logl(c/64+1)/LOG2+0.45), 1)*GRADIENTLENGTH + 0.5;
|
|
image[imgidx++] = colors[idx][0];
|
|
image[imgidx++] = colors[idx][1];
|
|
image[imgidx++] = colors[idx][2];
|
|
}
|
|
}
|
|
}
|
|
// write out image
|
|
printf("P6 %d %d 255\n", width, height);
|
|
fwrite(image, 1, width*height*3, stdout);
|
|
fprintf(stderr, "%d periods found\n", foundperiods);
|
|
|
|
return 0;
|
|
}
|