1 files changed, 396 insertions, 0 deletions

diff --git a/sprite2gba/src/main.c b/sprite2gba/src/main.c
new file mode 100644
index 0000000..f91ecd0
--- /dev/null
+++ b/sprite2gba/src/main.c
@@ -0,0 +1,396 @@
+#include <getopt.h>
+
+#include "shorthand.h"
+
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
+
+#define TILE_SIZE 8
+#define DEFAULT_PALETTE_SIZE 16
+#define DEFAULT_BG_COLOR 0x0000
+
+typedef u16 Color;
+
+static inline Color
+rgb15(u32 red, u32 green, u32 blue ) {
+    return (blue << 10) | (green << 5) | red;
+}
+
+static inline
+int quantize5(int color) {
+    return color * 31 / 255;
+}
+
+// TODO: Assuming 4bpp tiles. The tile is an index to a palette.
+// TODO: Write more documentation about this.
+typedef u32 Tile[TILE_SIZE];
+
+typedef struct Tiles {
+    Tile *data;
+    size_t size;
+    size_t capacity;
+} Tiles;
+
+typedef struct Palette {
+    Color *data;
+    size_t size;
+    size_t capacity;
+} Palette;
+
+typedef struct Image {
+    unsigned char *data;
+    int width;
+    int height;
+    int n_channels;
+} Image;
+
+u8
+pack_1bb(u32 hex) {
+    u32 low_nibble = hex & 0xFFFF;
+    u32 high_nibble = (hex >> 16) & 0xFFFF;
+    u32 low = (low_nibble & 0x1);
+    low += 2 * ((low_nibble >> 4) & 0x1);
+    low += 4 * ((low_nibble >> 8) & 0x1);
+    low += 8 * ((low_nibble >> 12) & 0x1);
+    u32 high = (high_nibble & 0x1);
+    high += 2 * ((high_nibble >> 4) & 0x1);
+    high += 4 * ((high_nibble >> 8) & 0x1);
+    high += 8 * ((high_nibble >> 12) & 0x1);
+    return (high << 4) | low;
+}
+
+void
+export_c_file(Tiles *tiles, Palette *palette, FILE *file, bool pack_1bpp) {
+    // Output tiles.
+    if (pack_1bpp) {
+        fprintf(file, "u32 packed_tiles[] = {\n    ");
+        size_t counter = 0;
+        for (size_t i = 0; i < tiles->capacity; ++i) {
+            for (size_t j = 0; j < TILE_SIZE; j += 4, counter++) {
+                if (counter == 4) {
+                    counter = 0;
+                    fprintf(file, "\n    ");
+                }
+                u32 tile_a = tiles->data[i][j];
+                u32 tile_b = tiles->data[i][j + 1];
+                u32 tile_c = tiles->data[i][j + 2];
+                u32 tile_d = tiles->data[i][j + 3];
+                u32 packed = pack_1bb(tile_d);
+                packed |= pack_1bb(tile_c) << 8;
+                packed |= pack_1bb(tile_b) << 16;
+                packed |= pack_1bb(tile_a) << 24;
+                fprintf(file, "0x%08x,", packed);
+                if (counter < 3) {
+                    fprintf(file, " ");
+                }
+            }
+        }
+        fprintf(file, "\n};\n");
+        fprintf(file, "\n");
+    } else {
+        fprintf(file, "u32 tiles[%lu][%u] = {\n", tiles->capacity, TILE_SIZE);
+        for (size_t i = 0; i < tiles->capacity; ++i) {
+            fprintf(file, "    {");
+            for (size_t j = 0; j < TILE_SIZE; ++j) {
+                fprintf(file, "0x%08x", tiles->data[i][j]);
+                if (j != (TILE_SIZE - 1)) {
+                    fprintf(file, ", ");
+                }
+            }
+            fprintf(file, "},\n");
+        }
+        fprintf(file, "};\n");
+        fprintf(file, "\n");
+    }
+
+    // Output palette.
+    fprintf(file, "u16 palette[%lu] = {\n", palette->capacity);
+    fprintf(file, "    ");
+    size_t counter = 0;
+    for (size_t i = 0; i < palette->capacity; ++i, ++counter) {
+            if (counter == 4) {
+                counter = 0;
+                fprintf(file, "\n    ");
+            }
+            fprintf(file, "0x%04x,", palette->data[i]);
+            if (counter < 3) {
+                fprintf(file, " ");
+            }
+    }
+    fprintf(file, "\n");
+    fprintf(file, "};\n");
+}
+
+void
+extract_tile(Tiles *tiles, Palette *palette, Image *img,
+        size_t offset_x, size_t offset_y) {
+    for (size_t j = 0; j < TILE_SIZE; ++j) {
+        u32 col_index = 0x00000000;
+        for (size_t i = 0; i < TILE_SIZE; ++i) {
+            size_t pal_index = palette->size;
+            // Find the memory index for this pixel.
+            int idx = (i + offset_x) + (j + offset_y) * img->width;
+            idx *= img->n_channels;
+
+            int red = img->data[idx];
+            int green = img->data[idx + 1];
+            int blue = img->data[idx + 2];
+
+            // Quantize to 5 bits per channel.
+            red = quantize5(red);
+            green = quantize5(green);
+            blue = quantize5(blue);
+
+            Color clr = rgb15(red, green, blue);
+            bool found = false;
+            // Brute force search, but since the palette size will likely be
+            // small, shouldn't be a big problem.
+            if (palette->size < palette->capacity) {
+                // If the palette is not full try to find if the color is
+                // already stored.
+                for (size_t p = 0; p < palette->capacity; ++p) {
+                    if (clr == palette->data[p]) {
+                        pal_index = p;
+                        found = true;
+                        break;
+                    }
+                }
+            } else {
+                // If the palette is full, find the closest perceived color
+                // instead.
+                size_t best_index = 0;
+                double best_distance = 1e99;
+                for (size_t p = 0; p < palette->capacity; ++p) {
+                    Color pal_clr = palette->data[p];
+                    int pal_red = pal_clr & 0x1F;
+                    int pal_green = (pal_clr >> 5) & 0x1F;
+                    int pal_blue = (pal_clr >> 10) & 0x1F;
+                    double r = (pal_red - red);
+                    double g = (pal_green - green);
+                    double b = (pal_blue - blue);
+                    double distance = r * r * 0.3 + g * g * 0.59 + b * b * 0.11;
+                    if (distance < best_distance) {
+                        best_distance = distance;
+                        best_index = p;
+                    }
+                }
+                pal_index = best_index;
+                found = true;
+            }
+            if (!found) {
+                palette->data[palette->size++] = clr;
+            }
+            col_index |= pal_index << i * 4; // TODO: FlipH?
+        }
+        tiles->data[tiles->size][j] = col_index;
+    }
+    tiles->size++;
+}
+
+void
+print_usage(void) {
+    printf("Usage: %s [options] <filename>\n", BIN_NAME);
+    printf("\n");
+    printf("\t-b <RRGGBB>\tSelects the background color used for transparency.\n");
+    printf("\t-o <out_file.c>\tPath to the output file. If blank, stdout will be used.\n");
+    printf("\t-x <0>\tStart x position (in pixels).\n");
+    printf("\t-y <0>\tStart y position (in pixels).\n");
+    printf("\t-W <8>\tSelect the sprite width in pixels. Must be a multiple of the tile size.\n");
+    printf("\t-H <8>\tSelect the sprite height in pixels. Must be a multiple of the tile size.\n");
+    printf("\t-1\tBit pack the output to 1bbp (4x size reduction).\n");
+    printf("\t-w <0>\tWidth of region to extract from (x0,y0). Defaults to image width.\n");
+    printf("\t-h <0>\tHeight of region to extract from (x0,y0). Defaults to image height.\n");
+    printf("\n");
+}
+
+// TODO: Support multiple files at once?
+int
+main(int argc, char *argv[]) {
+    // Initialize default parameters.
+    u16 background_color = DEFAULT_BG_COLOR;
+    u16 palette_size = DEFAULT_PALETTE_SIZE;
+    size_t sprite_width = TILE_SIZE;
+    size_t sprite_height = TILE_SIZE;
+    char *out_file_path = NULL;
+    bool pack_1bpp = false;
+    size_t start_x = 0;
+    size_t start_y = 0;
+    size_t width = 0;
+    size_t height = 0;
+
+    int option;
+    while ((option = getopt(argc, argv, "b:o:W:H:1x:y:w:h:")) != -1) {
+        switch (option) {
+            case 'b': {
+                // Background color.
+                char *bg = optarg;
+                if (strlen(bg) != 6) {
+                    fprintf(stderr, "%s: Invalid background color.\n", BIN_NAME);
+                    print_usage();
+                    return EXIT_FAILURE;
+                }
+                unsigned int red = 0;
+                unsigned int green = 0;
+                unsigned int blue = 0;
+
+                // NOTE: Undefined behaviour, here we go! Also, no error checks,
+                // so if an invalid number is given it will be parsed as 0.
+                char r_str[3] = {bg[0], bg[1], '\0'};
+                char g_str[3] = {bg[2], bg[3], '\0'};
+                char b_str[3] = {bg[4], bg[5], '\0'};
+                sscanf(r_str, "%x", &red);
+                sscanf(g_str, "%x", &green);
+                sscanf(b_str, "%x", &blue);
+
+                // Quantize and transform to rgb15.
+                red = quantize5(red);
+                green = quantize5(green);
+                blue = quantize5(blue);
+                background_color = rgb15(red, green, blue);
+            } break;
+            case 'W': {
+                // Sprite width.
+                char *arg = optarg;
+                sprite_width = 0;
+                sprite_width = atoi(arg);
+
+                // Check if a valid number is given.
+                if (sprite_width == 0 || sprite_width % TILE_SIZE != 0) {
+                    fprintf(stderr, "%s: Invalid sprite width.\n", BIN_NAME);
+                    print_usage();
+                    return EXIT_FAILURE;
+                }
+            } break;
+            case 'H': {
+                // Sprite height.
+                char *arg = optarg;
+                sprite_height = 0;
+                sprite_height = atoi(arg);
+
+                // Check if a valid number is given.
+                if (sprite_height == 0 || sprite_height % TILE_SIZE != 0) {
+                    fprintf(stderr, "%s: Invalid sprite height.\n", BIN_NAME);
+                    print_usage();
+                    return EXIT_FAILURE;
+                }
+            } break;
+            case 'o': {
+                // Output file.
+                out_file_path = optarg;
+            } break;
+            case '1': {
+                // Pack output to 1bpp.
+                pack_1bpp = true;
+            } break;
+            case 'x': {
+                // Start x position in pixels.
+                start_x = atoi(optarg);
+            } break;
+            case 'y': {
+                // Start y position in pixels.
+                start_y = atoi(optarg);
+            } break;
+            case 'w': {
+                // Width of region to extract from (x0,y0).
+                width = atoi(optarg);
+            } break;
+            case 'h': {
+                // Height of region to extract from (x0,y0).
+                height = atoi(optarg);
+            } break;
+            default: {
+                print_usage();
+                return EXIT_FAILURE;
+            } break;
+        }
+    }
+
+    // Get the path to the file to be exported.
+    if (optind != argc - 1) {
+        fprintf(stderr, "%s: No filename given.\n", BIN_NAME);
+        print_usage();
+        return EXIT_FAILURE;
+    }
+    char *file_name = argv[optind];
+
+    // Fill the palette with the background color if one was given.
+    Palette palette = {
+        .data = malloc(palette_size * sizeof(Color)),
+        .size = 1,
+        .capacity = palette_size,
+    };
+    for (size_t i = 0; i < palette_size; ++i) {
+        palette.data[i] = background_color;
+    }
+
+    Image img = {0};
+
+    // Open the given file.
+    FILE *input_file = fopen(file_name, "rb");
+    if (input_file == NULL) {
+        fprintf(stderr, "%s: can't open input file: %s\n", BIN_NAME, file_name);
+        return EXIT_FAILURE;
+    }
+    img.data = stbi_load_from_file(input_file, &img.width, &img.height, &img.n_channels, 0);
+    fclose(input_file);
+
+    // TODO: Implement support for different file inputs.
+    if (img.n_channels != 3) {
+        fprintf(stderr, "File format not supported. Only 3 channel files for now.\n");
+        return EXIT_FAILURE;
+    }
+
+    if (width == 0) {
+        width = img.width;
+    }
+    if (height == 0) {
+        height = img.height;
+    }
+    size_t n_tiles_x = width / TILE_SIZE;
+    size_t n_tiles_y = height / TILE_SIZE;
+    size_t n_tiles = n_tiles_x * n_tiles_y;
+
+    // Allocate memory for the tiles in this file, with zero-initialization.
+    Tiles tiles = {
+        .data = calloc(n_tiles, sizeof(Tile)),
+        .size = 0,
+        .capacity = n_tiles,
+    };
+
+    int offset_x = start_x;
+    int offset_y = start_y;
+    size_t n_sprites_x = width / sprite_width;
+    size_t n_sprites_y = height / sprite_height;
+    size_t n_sprite_tiles_x = sprite_width / TILE_SIZE;
+    size_t n_sprite_tiles_y = sprite_height / TILE_SIZE;
+    for (size_t p = 0; p < n_sprites_y; ++p) {
+        for (size_t k = 0; k < n_sprites_x; ++k) {
+            for (size_t j = 0; j < n_sprite_tiles_y; ++j) {
+                int offset_x = start_x + k * sprite_width;
+                int offset_y = start_y + p * sprite_height + j * TILE_SIZE;
+                for (size_t i = 0; i < n_sprite_tiles_x; ++i) {
+                    extract_tile(&tiles, &palette, &img, offset_x, offset_y);
+                    offset_x += TILE_SIZE;
+                }
+            }
+        }
+    }
+
+    if (out_file_path == NULL) {
+        export_c_file(&tiles, &palette, stdout, pack_1bpp);
+    } else {
+        FILE *file = fopen(out_file_path, "w");
+        if (!file) {
+            fprintf(stderr, "%s: can't open output file: %s\n", BIN_NAME, out_file_path);
+            return EXIT_FAILURE;
+        }
+        export_c_file(&tiles, &palette, file, pack_1bpp);
+        fclose(file);
+    }
+
+    // Cleanup resources and exit.
+    free(tiles.data);
+    free(palette.data);
+    stbi_image_free(img.data);
+    return EXIT_SUCCESS;
+}