ref: d0346f42fdad3ec4f6c6652812829034ac10742d
dir: /test/gfx/randtilegen.c/
/* * This file is part of RGBDS. * * Copyright (c) 2022, Eldred Habert and RGBDS contributors. * * SPDX-License-Identifier: MIT * * Originally: * // This program is hereby released to the public domain. * // ~aaaaaa123456789, released 2022-03-15 * https://gist.github.com/aaaaaa123456789/3feccf085ab4f82d144d9a47fb1b4bdf * * This was modified to use libpng instead of libplum, as well as comments and style changes. */ #include <assert.h> #include <errno.h> #include <limits.h> #include <png.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "platform.h" #define STR(x) #x #define XSTR(x) STR(x) struct Attributes { unsigned char palette; unsigned char nbColors; }; static unsigned long long randbits = 0; static unsigned char randcount = 0; static _Noreturn void fatal(char const *error) { fprintf(stderr, "FATAL: %s\n", error); exit(1); } static FILE *seed; static unsigned long long getRandomBits(unsigned count) { while (count > randcount) { // Get new random bytes from stdin (assumed to be a stream of random data) to fulfill the // random bits request int data = getc(seed); if (data == EOF) { exit(0); } randbits |= (unsigned long long)data << randcount; randcount += 8; } unsigned long long result = randbits & ((1ull << count) - 1); randbits >>= count; randcount -= count; return result; } static void generate_tile_attributes(struct Attributes * restrict attributes) { /* * Images have ten colors, grouped into two groups of 5 colors. The palette index indicates two * things: which one of those groups will be used, and which colors out of those 5 will be used * by the tile. The low bit indicates the group, and the rest of the value indicates the subset * of colors. The remainder of the number is treated as a bitfield, where each bit represents a * color: for instance, a value of 13 in the upper bits (binary 01101) indicates that colors 0, * 2 and 3 from that group will be used. Values of 0 and 31 are naturally invalid because they * indicate zero and five colors respectively, and 30 is also excluded to ensure that the * particular subset of colors 1, 2, 3 and 4 never shows up. This guarantees that every tile * will be representable using a palette containing color 0 (since those that don't contain * color 0 will have three colors at most), which in turn ensures that only 4 palettes per group * (and thus 8 total) are needed to cover the image: 0, 1, 2, 3; 0, 1, 2, 4; 0, 1, 3, 4; and 0, * 2, 3, 4. This also implies that making color 0 transparent (in both groups) adds a * transparent color to every palette. */ unsigned char pal; do { pal = getRandomBits(5); } while (pal == 0 || (pal > 29)); attributes->palette = 2 * pal + getRandomBits(1); // Use an array to look up the number of colors in the palette; this is faster (and simpler) // than doing a population count over the bits static char const popcount[] = {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4}; attributes->nbColors = popcount[pal]; } static void generate_tile_data(unsigned char tiledata[ARR_QUALS(restrict) MIN_NB_ELMS(8)][8], unsigned colorcount) { switch (colorcount) { case 2: // 1bpp for (uint8_t y = 0; y < 8; y++) { for (uint8_t x = 0; x < 8; x++) { tiledata[y][x] = getRandomBits(1); } } break; case 4: // 2bpp for (uint8_t y = 0; y < 8; y++) { for (uint8_t x = 0; x < 8; x++) { tiledata[y][x] = getRandomBits(2); } } break; case 3: // 2bpp with resampling for (uint8_t y = 0; y < 8; y++) { for (uint8_t x = 0; x < 8; x++) { do { tiledata[y][x] = getRandomBits(2); } while (tiledata[y][x] == 3); } } } } // Can't mark as `const`, as the array type is otherwise not compatible (augh) static void copy_tile_data(unsigned char destination[ARR_QUALS(restrict) MIN_NB_ELMS(8)][8], unsigned char /* const */ source[ARR_QUALS(restrict) MIN_NB_ELMS(8)][8]) { // Apply a random rotation to the copy // coord ^ 7 = inverted coordinate; coord ^ 0 = regular coordinate unsigned xmask = getRandomBits(1) * 7; unsigned ymask = getRandomBits(1) * 7; for (unsigned y = 0; y < 8; y++) { for (unsigned x = 0; x < 8; x++) { destination[y][x] = source[y ^ ymask][x ^ xmask]; } } } static void generate_palettes(uint16_t palettes[ARR_QUALS(restrict) MIN_NB_ELMS(60)][4]) { uint16_t colors[10]; // Generate 10 random colors (two groups of 5 colors) for (unsigned p = 0; p < 10; p++) { colors[p] = getRandomBits(15); } // Potentially make the first color of each group transparent if (!getRandomBits(2)) { colors[0] |= 0x8000; colors[5] |= 0x8000; } for (unsigned p = 0; p < 60; p++) { uint16_t const *group = colors + 5 * (p & 1); uint16_t *palette = palettes[p]; for (unsigned index = 0; index < 5; index++) { if (p & (2 << index)) { *(palette++) = group[index]; } } } } /** * Expand a 5-bit color component to 8 bits with minimal bias */ static uint8_t _5to8(uint8_t five) { return five << 3 | five >> 2; } // Can't mark as `const`, as the array type is otherwise not compatible (augh) static void write_image(char const *filename, uint16_t /* const */ palettes[MIN_NB_ELMS(60)][4], unsigned char /* const */ (*tileData)[8][8], struct Attributes const *attributes, uint8_t width, uint8_t height) { uint8_t const nbTiles = width * height; png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); png_infop pngInfo = png_create_info_struct(png); if (setjmp(png_jmpbuf(png))) { fprintf(stderr, "FATAL: An error occurred while writing image \"%s\"", filename); exit(1); } FILE *file = fopen(filename, "wb"); if (file == NULL) { fprintf(stderr, "FATAL: Failed to open \"%s\": %s\n", filename, strerror(errno)); exit(1); } png_init_io(png, file); png_set_IHDR(png, pngInfo, width * 8, height * 8, 8, PNG_COLOR_TYPE_RGB_ALPHA, getRandomBits(1) ? PNG_INTERLACE_NONE : PNG_INTERLACE_ADAM7, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); // While it would be nice to write the image little by little, I really don't want to handle // interlacing myself. (We're doing interlacing to test that RGBGFX correctly handles it.) uint8_t const SIZEOF_PIXEL = 4; // Each pixel is 4 bytes (RGBA @ 8 bits/component) assert(width != 0); assert(height != 0); uint8_t *data = malloc(height * 8 * width * 8 * SIZEOF_PIXEL); uint8_t **rowPtrs = malloc(height * 8 * sizeof(*rowPtrs)); if (data == NULL || rowPtrs == NULL) { fatal("Out of memory"); } for (uint8_t y = 0; y < height * 8; ++y) { rowPtrs[y] = &data[y * width * 8 * SIZEOF_PIXEL]; } for (uint8_t p = 0; p < nbTiles; p++) { uint8_t const tx = 8 * (p % width), ty = 8 * (p / width); for (uint8_t y = 0; y < 8; y++) { uint8_t * const row = rowPtrs[ty + y]; for (uint8_t x = 0; x < 8; x++) { uint8_t * const pixel = &row[(tx + x) * SIZEOF_PIXEL]; uint16_t const color = palettes[attributes[p].palette][tileData[p][y][x]]; pixel[0] = _5to8(color & 0x1F); pixel[1] = _5to8(color >> 5 & 0x1F); pixel[2] = _5to8(color >> 10 & 0x1F); pixel[3] = color & 0x8000 ? 0x00 : 0xFF; } } } png_set_rows(png, pngInfo, rowPtrs); png_write_png(png, pngInfo, PNG_TRANSFORM_IDENTITY, NULL); fclose(file); free(rowPtrs); free(data); png_destroy_write_struct(&png, &pngInfo); } static void generate_random_image(char const *filename) { #define MIN_TILES_PER_SIDE 3 #define MAX_TILES ((MIN_TILES_PER_SIDE + 7) * (MIN_TILES_PER_SIDE + 7)) struct Attributes attributes[MAX_TILES]; unsigned char tileData[MAX_TILES][8][8]; uint8_t width = getRandomBits(3) + MIN_TILES_PER_SIDE, height = getRandomBits(3) + MIN_TILES_PER_SIDE; for (uint8_t tile = 0; tile < (width * height); tile++) { generate_tile_attributes(attributes + tile); // If a tile contains only one color, then there's no tile data to generate: all pixels will // use color 0 if (attributes[tile].nbColors < 2) { memset(tileData[tile], 0, sizeof(tileData[tile])); continue; } // Find tiles with the same number of colors unsigned index = 0, total = 0; for (; index < tile; index++) { if (attributes[index].nbColors == attributes[tile].nbColors) { total++; } } assert(index == tile); // This is used as a sentinel later on to indicate no tile was found if (total) { // If there are such tiles, there's a random chance that this tile will replicate one of // those tiles (potentially rotated) index = getRandomBits(8); if (index < total) { total = index + 1; for (index = 0; total; index++) { if (attributes[index].nbColors == attributes[tile].nbColors) { total--; } } if (total == 0) { index--; } } else { index = tile; // Restore the sentinel } } if (index == tile) { generate_tile_data(tileData[tile], attributes[index].nbColors); } else { copy_tile_data(tileData[tile], tileData[index]); } } uint16_t palettes[60][4]; generate_palettes(palettes); write_image(filename, palettes, tileData, attributes, width, height); } int main(int argc, char **argv) { if (argc < 3 || argc > 4) { fprintf(stderr, "usage: %s <input file> <basename> [<maxcount>]\n", argv[0]); return 2; } seed = fopen(argv[1], "rb"); if (!seed) { fprintf(stderr, "FATAL: Cannot open seed file (%s)\n", strerror(errno)); return 1; } size_t const nameLen = strlen(argv[2]); unsigned long long maxcount = ULLONG_MAX; if (argc > 3) { char *error; maxcount = strtoull(argv[3], &error, 0); if (*error != '\0') { fatal("invalid count"); } } char *filename = malloc(nameLen + sizeof(XSTR(ULLONG_MAX) ".png")); if (!filename) { fatal("out of memory"); } memcpy(filename, argv[2], nameLen); for (unsigned long long count = 0; count < maxcount; count++) { sprintf(&filename[nameLen], "%llu.png", count); generate_random_image(filename); // Reset the global random state so that subsequent images don't share a random byte randbits = 0; randcount = 0; } return 0; }