105 lines
3.6 KiB
C
105 lines
3.6 KiB
C
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#include "colors.h"
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#include <quadmath.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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int main(int argc, char **argv) {
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if (argc != 6) {
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fprintf(stderr, "usage: %s width height centerx centery magnification", argv[0]);
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return 1;
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}
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__float128 eps = 1e-17;
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__float128 Q1LOG2, LOG2;
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Q1LOG2 = strtoflt128("1.44269504088896340735992468100189213742664595415299", NULL);
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LOG2 = strtoflt128("0.69314718055994530941723212145817656807550013436026", NULL);
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unsigned int width = atoi(argv[1]);
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unsigned int height = atoi(argv[2]);
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char* image = malloc(width*height*3);
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int x, y;
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__float128 centerx, centery;
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centerx = strtoflt128(argv[3], NULL);
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centery = strtoflt128(argv[4], NULL);
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__float128 bailout = 128;
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__float128 logLogBailout = logq(logq(bailout));
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int foundperiods = 0;
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__float128 magn = strtoflt128(argv[5], NULL);
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long maxiter = width * sqrtq(magn);
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__float128 x0d = 4 / magn / width;
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__float128 x2 = -2 / magn + centerx;
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__float128 y1d = -4 / magn / width;
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__float128 y2 = 2 / magn * height / width + centery;
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int imgidx = 0;
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for (y = 0; y < height; y++) {
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for (x = 0; x < width; x++) {
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fprintf(stderr, "\r%f %%", (float)imgidx/(width*height*3)*100);
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__float128 px = x*x0d + x2;
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__float128 py = y*y1d + y2;
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// no Main bulb or Cardoid check to be faster
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__float128 zx = px;
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__float128 zy = py;
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long i;
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// Initial maximum period to detect.
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int check = 3;
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// Maximum period doubles every iterations:
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int whenupdate = 10;
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// Period history registers.
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__float128 hx = 0;
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__float128 hy = 0;
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__float128 xx, yy;
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bool inside = true;
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for (i = 1; i <= maxiter; i++) {
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xx = zx * zx;
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yy = zy * zy;
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if (xx + yy > bailout) {
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inside = false;
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break;
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}
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// iterate
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zy = 2 * zx * zy + py;
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zx = xx - yy + px;
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// periodicity check
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__float128 d = zx - hx;
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if (d > 0.0 ? d < eps : d > -eps) {
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d = zy - hy;
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if (d > 0.0 ? d < eps : d > -eps) {
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// Period found.
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foundperiods++;
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break;
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}
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}
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if ((i & check) == 0) {
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if (--whenupdate == 0) {
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whenupdate = 10;
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check <<= 1;
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check++;
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}
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// period = 0;
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hx = zx;
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hy = zy;
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}
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}
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if (inside) {
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image[imgidx++] = 0;
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image[imgidx++] = 0;
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image[imgidx++] = 0;
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} else {
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__float128 r = sqrtq(zx*zx + zy*zy);
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__float128 c = i - 1.28 + (logLogBailout - logq(logq(r))) * Q1LOG2;
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int idx = fmodq((logq(c/64+1)/LOG2+0.45), 1)*GRADIENTLENGTH + 0.5;
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image[imgidx++] = colors[idx][0];
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image[imgidx++] = colors[idx][1];
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image[imgidx++] = colors[idx][2];
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}
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}
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}
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// write out image
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printf("P6 %d %d 255\n", width, height);
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fwrite(image, 1, width*height*3, stdout);
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//fprintf(stderr, "%d periods found\n", foundperiods);
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return 0;
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}
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