ref: 797f8bc3a2be6ddec3497496e9989ab66d21800e
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;
}