textool.cpp

#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#define STB_RECT_PACK_IMPLEMENTATION
#include "stb_image.h"
#include "stb_image_write.h"
#include "stb_rect_pack.h"
#include "bitmap.h"
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

struct Image
{
	const char *name;
	unsigned char *data;
	int width, height;
};

int main(int argc, char **argv)
{
	int capacity = argc - 1;
	stbrp_rect *rects = (stbrp_rect*)calloc(capacity, sizeof(stbrp_rect));
	Image *images = (Image*)calloc(capacity, sizeof(Image));

	int success = 1;

	int count = 0;
	for (int i = 1; i < argc; i++) {
		int width, height, channels;
		unsigned char *data = stbi_load(argv[i], &width, &height, &channels, 4);
		if (channels != 4) {
			fprintf(stderr, "Wrong number of components in file '%s', skipping...\n", argv[i]);
			success = 0;
			continue;
		}

		rects[count].id = count;
		rects[count].w = (stbrp_coord)width;
		rects[count].h = (stbrp_coord)height;

		images[count].name = argv[i];
		images[count].data = data;
		images[count].width = width;
		images[count].height = height;
		count++;
	}

	int atlas_size = 1024;

	stbrp_node *nodes = (stbrp_node*)malloc(sizeof(stbrp_node) * atlas_size);
	stbrp_context rp_ctx;
	stbrp_init_target(&rp_ctx, atlas_size, atlas_size, nodes, atlas_size);

	stbrp_pack_rects(&rp_ctx, rects, count);

	unsigned char *data = (unsigned char*)calloc(atlas_size * atlas_size, 4);

	for (int i = 0; i < count; i++) {
		Image *image = images + rects[i].id;
		if (!rects[i].was_packed) {
			fprintf(stderr, "Could not pack '%s', skipping...\n", image->name);
			success = 0;
			continue;
		}

		int bx = rects[i].x;
		int by = rects[i].y;
		int w = image->width;
		int h = image->height;

		unsigned char *src = images[i].data;

		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {
				int si = (y * w + x) * 4;
				int di = ((by + y) * atlas_size + x + bx) * 4;

				data[di + 0] = src[si + 0];
				data[di + 1] = src[si + 1];
				data[di + 2] = src[si + 2];
				data[di + 3] = src[si + 3];
			}
		}
	}

	free(nodes);

	stbi_write_png("atlas.png", atlas_size, atlas_size, 4, data, atlas_size * 4);

	return success ? 0 : 1;
}