1 files changed, 122 insertions, 6 deletions

diff --git a/gfx-iso/asset/mkasset.py b/gfx-iso/asset/mkasset.py
index 15f7912..b4e335f 100644
--- a/gfx-iso/asset/mkasset.py
+++ b/gfx-iso/asset/mkasset.py
@@ -1,15 +1,24 @@
-# Converts tile sets and tile maps to binary formats (.TS, .TM) for the engine.
+# Converts assets to binary formats (.ts, .tm, .ss) for the engine.
 #
-# Currently handles Tiled's .tsx and .tmx file formats.
+# Input file formats:
+#  - Tiled tile set (.tsx)
+#  - Tiled tile map (.tmx)
+#  - Sprite sheets (.jpg, .png, etc), 1 row per animation.
+#
+# Output file formats:
+#  - Binary tile set file (.ts)
+#  - Binary tile map file (.tm)
+#  - Binary sprite sheet file (.ss)
 #
-# The output is a binary tile set file (.TS) or a binary tile map file (.TM).
 import argparse
 import ctypes
+import os
 from PIL import Image
 import sys
 from xml.etree import ElementTree
 
 # Maximum length of path strings in .TS and .TM files.
+# Must match the engine's value.
 MAX_PATH_LENGTH = 128
 
 
@@ -133,20 +142,127 @@ def convert_tmx(input_filepath, output_filepath):
                         output.write(ctypes.c_uint16(int(tile_id)))
 
 
+def get_num_cols(image, sprite_width):
+    """Return the number of non-empty columns in the image.
+
+    Assumes no gaps in the columns.
+    """
+    assert (image.width % sprite_width == 0)
+    num_cols = image.width // sprite_width
+
+    # Start the search from right to left.
+    for col in reversed(range(1, num_cols)):
+        left = (col - 1) * sprite_width
+        right = col * sprite_width
+        rect = image.crop((left, 0, right, image.height))
+        min_max = rect.getextrema()
+        for (channel_min, channel_max) in min_max:
+            if channel_min != 0 or channel_max != 0:
+                # 'col' is the rightmost non-empty column.
+                # Assuming no gaps, col+1 is the number of non-empty columns.
+                return col + 1
+
+    return 0
+
+
+def get_sprite_sheet_rows(input_filepath, sprite_width, sprite_height):
+    """Gets the individual rows of a sprite sheet.
+
+    The input sprite sheet can have any number of rows.
+
+    Returns a list of lists [[sprite bytes]], one inner list for the columns in
+    each row.
+    """
+    with Image.open(input_filepath) as im:
+        # Sprite sheet's width and height must be integer multiples of the
+        # sprite's width and height.
+        assert (im.width % sprite_width == 0)
+        assert (im.height % sprite_height == 0)
+
+        num_rows = im.height // sprite_height
+
+        rows = []
+        for row in range(num_rows):
+            # Get the number of columns.
+            upper = row * sprite_height
+            lower = (row + 1) * sprite_height
+            whole_row = im.crop((0, upper, im.width, lower))
+            num_cols = get_num_cols(whole_row, sprite_width)
+            assert (num_cols > 0)
+
+            # Crop the row into N columns.
+            cols = []
+            for i in range(num_cols):
+                left = i * sprite_width
+                right = (i + 1) * sprite_width
+                sprite = im.crop((left, upper, right, lower))
+                cols.append(sprite)
+
+            sprite_bytes = [sprite.convert('RGBA').tobytes() for sprite in cols]
+            assert (len(sprite_bytes) == num_cols)
+            rows.append(sprite_bytes)
+
+        return rows
+
+
+def convert_sprite_sheet(input_file_paths, sprite_width, sprite_height,
+                         output_filepath):
+    """Converts a set of sprite sheet images into a binary sprite sheet file
+    (.ss).
+
+    The input sprite sheets can have any number of rows, one row per animation.
+    All rows from all sprite sheets are concatenated in the output file.
+
+    The sprite's width and height is assumed constant throughout the input
+    sprite sheets.
+    """
+    rows = []
+
+    for sprite_sheet in input_file_paths:
+        rows.extend(
+            get_sprite_sheet_rows(sprite_sheet, sprite_width, sprite_height))
+
+    with open(output_filepath, 'bw') as output:
+        output.write(ctypes.c_uint16(sprite_width))
+        output.write(ctypes.c_uint16(sprite_height))
+        output.write(ctypes.c_uint16(len(rows)))
+
+        print(f"Sprite width:  {sprite_width}")
+        print(f"Sprite height: {sprite_height}")
+        print(f"Rows:          {len(rows)}")
+
+        for sprites in rows:
+            output.write(ctypes.c_uint16(len(sprites)))
+            for sprite_bytes in sprites:
+                output.write(sprite_bytes)
+
+
 def main():
     parser = argparse.ArgumentParser()
-    parser.add_argument("input", help="Input file (.tsx, .tmx)")
+    parser.add_argument("input",
+                        nargs="+",
+                        help="Input file (.tsx, .tmx) or path regex (sprite sheets)")
+    parser.add_argument("--width", type=int, help="Sprite width in pixels")
+    parser.add_argument("--height", type=int, help="Sprite height in pixels")
+    parser.add_argument("--out", help="Output file (sprite sheets)")
     args = parser.parse_args()
 
-    output_filepath_no_ext = drop_extension(args.input)
     if ".tsx" in args.input:
+        output_filepath_no_ext = drop_extension(args.input)
         output_filepath = output_filepath_no_ext + ".ts"
         convert_tsx(args.input, output_filepath)
     elif ".tmx" in args.input:
+        output_filepath_no_ext = drop_extension(args.input)
         output_filepath = output_filepath_no_ext + ".tm"
         convert_tmx(args.input, output_filepath)
     else:
-        print(f"Unhandled file format: {args.input}")
+        # Sprite sheets.
+        if not args.width or not args.height:
+            print("Sprite width and height must be given")
+            return 1
+        output_filepath = args.out if args.out else "out.ss"
+        convert_sprite_sheet(args.input, args.width, args.height,
+                             output_filepath)
 
     return 0