116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/*
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* fractal
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* Written in 2020 by Lucas
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* CC0 1.0 Universal/Public domain - No rights reserved
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*
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* To the extent possible under law, the author(s) have dedicated all
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* copyright and related and neighboring rights to this software to the
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* public domain worldwide. This software is distributed without any
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* warranty. You should have received a copy of the CC0 Public Domain
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* Dedication along with this software. If not, see
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* <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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/* gepopt visibility for GLIBC */
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#if !defined(__OpenBSD__)
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#define _DEFAULT_SOURCE
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#endif
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#include <limits.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "palette.h"
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#include "pnmout.h"
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#include "util.h"
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#define CLAMP(x, a, b) ((x) < (a) ? (a) : (x) > (b) ? (b) : (x))
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static double
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bezier3(double t, double p0, double p1, double p2, double p3)
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{
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double u = 1.0 - t;
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return u * u * u * p0
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+ 3.0 * u * u * t * p1
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+ 3.0 * u * t * t * p2
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+ t * t * t * p3;
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}
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static double
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bezier4(double t, double p0, double p1, double p2, double p3)
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{
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return (1.0 - t) * bezier3(t, p0, p1, p2, p3)
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+ t * bezier3(t, p1, p2, p3, p0);
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}
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struct color *
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palette_gen(size_t n)
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{
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struct color *palette;
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double p[12] = {
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drand48(), drand48(), drand48(),
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drand48(), drand48(), drand48(),
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drand48(), drand48(), drand48(),
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drand48(), drand48(), drand48(),
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};
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double r, g, b, t;
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size_t i;
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if ((palette = malloc(n * sizeof(*palette))) == NULL)
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errx(1, "out of memory");
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for (i = 0; i < n; i++) {
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t = i / (double)n;
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r = bezier4(t, p[0], p[3], p[6], p[9]);
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g = bezier4(t, p[1], p[4], p[7], p[10]);
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b = bezier4(t, p[2], p[5], p[8], p[11]);
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palette[i].r = 65535.0 * CLAMP(r, 0.0, 1.0);
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palette[i].g = 65535.0 * CLAMP(g, 0.0, 1.0);
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palette[i].b = 65535.0 * CLAMP(b, 0.0, 1.0);
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}
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return palette;
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}
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static void
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usage(void)
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{
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fprintf(stderr, "Usage: %s palette [-h height] [-w width]\n",
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xgetprogname());
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exit(1);
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}
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int
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palette_main(int argc, char *argv[])
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{
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struct color *palette;
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int ch, i, j, width, height;
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height = 50;
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width = 500;
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while ((ch = getopt(argc, argv, "h:w:")) != -1)
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switch (ch) {
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case 'h':
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height = parse_integer(optarg, 1, 65535);
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break;
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case 'w':
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width = parse_integer(optarg, 1, 65535);
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break;
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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if (argc > 1)
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usage();
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palette = palette_gen(width);
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pnmout_header(stdout, width, height);
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for (i = 0; i < height; i++)
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for (j = 0; j < width; j++)
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pnmout_pixel(stdout, palette[j]);
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free(palette);
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return !(fflush(stdout) == 0);
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}
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