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Diffstat (limited to 'main.c')
| -rw-r--r-- | main.c | 281 |
1 files changed, 281 insertions, 0 deletions
@@ -0,0 +1,281 @@ +/********************************************************************* + * kd-forest * + * Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com> * + * * + * This program is free software. It comes without any warranty, to * + * the extent permitted by applicable law. You can redistribute it * + * and/or modify it under the terms of the Do What The Fuck You Want * + * To Public License, Version 2, as published by Sam Hocevar. See * + * the COPYING file or http://www.wtfpl.net/ for more details. * + *********************************************************************/ + +// Number of trailing zero bits on each color chanel, set to zero for all +// 24-bit images +#define ZERO_BITS 0 +// Whether to sort by hue +#define HUE_SORT 1 + +#if HUE_SORT +# define PASSES 16 +# define RANDOMIZE 0 +#else +# define PASSES 1 +# define RANDOMIZE 1 +#endif + +#include "kd-forest.h" +#include "util.h" +#include <errno.h> +#include <math.h> +#include <png.h> +#include <setjmp.h> +#include <stdio.h> +#include <stdlib.h> + +#if __unix__ +#include <unistd.h> +#endif + +unsigned int +rand_in(unsigned int range) +{ + // Compensate for bias if (RAND_MAX + 1) isn't a multiple of range + unsigned int limit = RAND_MAX + 1U - ((RAND_MAX + 1U)%range); + unsigned int res; + do { + res = rand(); + } while (res >= limit); + return res%range; +} + +kd_node_t * +try_neighbor(kd_node_t *node, unsigned int width, unsigned int height, + int which) +{ + int dx = which%3 - 1; + int dy = which/3 - 1; + + if (dx < 0 && node->x < -dx) { + return NULL; + } else if (dx > 0 && node->x + dx >= width) { + return NULL; + } else if (dy < 0 && node->y < -dy) { + return NULL; + } else if (dy > 0 && node->y + dy >= height) { + return NULL; + } + + return node + (int)width*dy + dx; +} + +kd_node_t * +next_neighbor(kd_node_t *node, unsigned int width, unsigned int height) +{ + unsigned int first = rand_in(9); + + for (unsigned int i = first; i < first + 9; ++i) { + int which = i%9; + if (which == 4) { + // Skip self + continue; + } + + kd_node_t *neighbor = try_neighbor(node, width, height, which); + if (neighbor && !neighbor->added) { + return neighbor; + } + } + + return NULL; +} + +void +remove_if_surrounded(kd_forest_t *kdf, kd_node_t *node, unsigned int width, + unsigned int height) +{ + if (node->added && !node->removed + && next_neighbor(node, width, height) == NULL) { + kdf_remove(kdf, node); + } +} + +void +remove_non_boundary(kd_forest_t *kdf, kd_node_t *node, unsigned int width, + unsigned int height) +{ + for (int i = 0; i < 9; ++i) { + kd_node_t *neighbor = try_neighbor(node, width, height, i); + if (neighbor) { + remove_if_surrounded(kdf, neighbor, width, height); + } + } +} + +#if HUE_SORT +#define PI 3.1415926535897932 + +static double +hue(uint32_t color) +{ + int R = (color >> 16) & 0xFF; + int G = (color >> 8) & 0xFF; + int B = color & 0xFF; + + double hue = atan2(sqrt(3.0)*(G - B), 2*R - G - B); + if (hue < 0.0) { + hue += 2.0*PI; + } + return hue; +} + +static int +hue_comparator(const void *a, const void *b) +{ + double ahue = hue(*(uint32_t *)a); + double bhue = hue(*(uint32_t *)b); + return (ahue > bhue) - (ahue < bhue); +} + +#endif + +int +main(void) +{ + const unsigned int jump = 1U << ZERO_BITS; + const unsigned int width = 1U << ((24 - 3*ZERO_BITS + 1)/2); // Round up + const unsigned int height = 1U << ((24 - 3*ZERO_BITS)/2); // Round down + const unsigned int size = width*height; + + printf("Generating a %ux%u image (%u pixels)\n", width, height, size); + + // Generate all the colors + uint32_t *colors = xmalloc(size*sizeof(uint32_t)); + for (unsigned int b = 0, i = 0; b < 0x100; b += jump) { + for (unsigned int g = 0; g < 0x100; g += jump) { + for (unsigned int r = 0; r < 0x100; r += jump, ++i) { + colors[i] = (r << 16) | (g << 8) | b; + } + } + } + srand(0); +#if RANDOMIZE + // Fisher-Yates shuffle + for (unsigned int i = size; i-- > 0;) { + unsigned int j = rand_in(i + 1); + uint32_t temp = colors[i]; + colors[i] = colors[j]; + colors[j] = temp; + } +#endif +#if HUE_SORT + qsort(colors, size, sizeof(uint32_t), hue_comparator); +#endif + + // Make a pool of potential k-d nodes + kd_node_t *nodes = xmalloc(size*sizeof(kd_node_t)); + for (unsigned int y = 0, i = 0; y < height; ++y) { + for (unsigned int x = 0; x < width; ++x, ++i) { + kd_node_init(nodes + y*width + x, x, y); + } + } + + // Make the forest + kd_forest_t kdf; + kdf_init(&kdf); + +#if __unix__ + bool tty = isatty(1); + const char *clear_line = tty ? "\033[2K\r" : ""; + const char *new_line = tty ? "" : "\n"; +#else + const char *clear_line = ""; + const char *new_line = "\n"; +#endif + + size_t max_size = 0; + + // Do multiple passes to get rid of artifacts in HUE_SORT mode + for (unsigned int i = 0, progress = 0; i < PASSES; ++i) { + for (unsigned int j = i; j < size; j += PASSES, ++progress) { + if (progress%width == 0) { + printf("%s%.2f%%\t| boundary size: %zu\t| max boundary size: %zu%s", + clear_line, 100.0*progress/size, kdf.size, max_size, new_line); + fflush(stdout); + } + + uint32_t color = colors[j]; + + kd_node_t target; + kd_node_set_color(&target, color); + + kd_node_t *new_node; + if (j == 0) { + // First node goes in the center + new_node = nodes + size/2 + width/2; + } else { + kd_node_t *nearest = kdf_find_nearest(&kdf, &target); + new_node = next_neighbor(nearest, width, height); + } + + kd_node_set_color(new_node, color); + kdf_insert(&kdf, new_node); + remove_non_boundary(&kdf, new_node, width, height); + + if (kdf.size > max_size) { + max_size = kdf.size; + } + } + } + printf("%s%.2f%%\t| boundary size: 0\t| max boundary size: %zu\n", + clear_line, 100.0, max_size); + + FILE *file = fopen("kd-forest.png", "wb"); + if (!file) { + abort(); + } + + png_structp png_ptr = + png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); + if (!png_ptr) { + abort(); + } + + png_infop info_ptr = png_create_info_struct(png_ptr); + if (!info_ptr) { + abort(); + } + + // libpng will longjmp here if it encounters an error from now on + if (setjmp(png_jmpbuf(png_ptr))) { + abort(); + } + + png_init_io(png_ptr, file); + png_set_IHDR(png_ptr, info_ptr, width, height, 8, + PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, + PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); + png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, PNG_sRGB_INTENT_ABSOLUTE); + + png_write_info(png_ptr, info_ptr); + + uint8_t *row = xmalloc(3*width*sizeof(uint8_t)); + for (unsigned int y = 0; y < height; ++y) { + for (unsigned int x = 0; x < width; ++x) { + kd_node_t *node = nodes + y*width + x; + row[3*x] = node->coords[0]; + row[3*x + 1] = node->coords[1]; + row[3*x + 2] = node->coords[2]; + } + png_write_row(png_ptr, (png_bytep)row); + } + + png_write_end(png_ptr, info_ptr); + + free(row); + png_destroy_write_struct(&png_ptr, &info_ptr); + fclose(file); + kdf_destroy(&kdf); + free(nodes); + free(colors); + return 0; +} |