1 files changed, 59 insertions, 0 deletions
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..665d3c8
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,59 @@
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
+#include <stdio.h>
+
+#define RGB(r, g, b) (((r) << 11) | ((g) << 5) | (b))
+
+static void
+output_tile(const uint8_t *data, int x, int y, int w)
+{
+	for (int iy = 0; iy < 16; iy += 1) {
+		putchar('\t');
+		for (int ix = 0; ix < 16; ix += 1) {
+			const int i = (ix + x + (iy + y) * w) * 3;
+			const int v = RGB(data[i]/8, data[i+1]/4, data[i+2]/8);
+			printf("%04x ", v);
+		}
+		putchar('\n');
+	}
+}
+
+int
+main(int argc, char **argv)
+{
+	if (argc != 1) {
+		fprintf(stderr, "usage: %s < tileset.png\n", argv[0]);
+		return 1;
+	}
+
+	/* Load image. */
+	int w, h, chans;
+	uint8_t *const data = stbi_load_from_file(stdin, &w, &h, &chans, 3);
+	if (data == NULL) {
+		fprintf(stderr, "stbi_load_from_file failed\n");
+		return 1;
+	}
+
+	if ((w & 15) || (h & 15)) {
+		fprintf(stderr, "invalid dimensions %dx%d, "
+		                "expected dimensions divisible by 16\n",
+		                w, h);
+		goto panic;
+	}
+	if (chans != 3) {
+		fprintf(stderr, "my lame utility only supports "
+		                "images using 3 color channels, "
+		                "yours has %d channels. too bad\n", chans);
+		goto panic;
+	}
+
+	for (int y = 0; y < h; y += 16)
+		for (int x = 0; x < w; x += 16)
+			output_tile(data, x, y, w);
+
+	stbi_image_free(data);
+	return 0;
+panic:
+	stbi_image_free(data);
+	return 0;
+}