Add script for generating collision maps from PNGs

.gitignore

@@ -1,4 +1,5 @@
+*.o
+*.2bpp
 is.gb
 is.gb.sym
-*.o
-*.2bpp
+png/map/*.s

Makefile

@@ -1,12 +1,15 @@
-PNGFILES := $(shell find png -type f -name '*.png')
+PNGFILES := $(shell find png/sprite -type f -name '*.png')
 IMGFILES := $(PNGFILES:%.png=%.2bpp)
 
+COLLFILES := $(shell find png/map -type f -name '*_coll.png')
+BUILT_COLLFILES := $(COLLFILES:%_coll.png=%.s)
+
 SFILES := $(shell find src -type f -name '*.s')
 OFILES := $(SFILES:%.s=%.o)
 
 .PHONY: clean
 
-is.gb is.gb.sym: $(IMGFILES) $(OFILES)
+is.gb is.gb.sym: $(IMGFILES) $(OFILES) $(BUILT_COLLFILES)
 	rgblink -o $@ -n $@.sym $(OFILES)
 	rgbfix -v $@
 
@@ -15,8 +18,11 @@ $(OFILES): $(IMGFILES)
 %.o: %.s
 	rgbasm -i inc -o $@ $<
 
-%.2bpp: %.png
+png/map/%.s: png/map/%_coll.png
+	python scripts/generate_coll_map.py -o $@ $<
+
+png/sprite/%.2bpp: png/sprite/%.png
 	rgbgfx -o $@ $<
 
 clean:
-	rm -f is.gb is.gb.sym $(IMGFILES) $(OFILES)
+	rm -f is.gb is.gb.sym $(IMGFILES) $(OFILES) $(BUILT_COLLFILES)

scripts/generate_coll_map.py

@@ -0,0 +1,71 @@
+import argparse
+import pathlib
+import sys
+
+from PIL import Image
+
+GREEN = (0, 255, 0)
+RED = (255, 0, 0)
+
+
+def generate_coll_map(in_path: str, out_path: str) -> None:
+    png = Image.open(in_path).convert("RGB")
+    assert png.height % 8 == 0 and png.width % 8 == 0
+
+    out_bytes = []
+    bits = []
+
+    for y in range(png.height // 8):
+        for x in range(png.width // 8):
+            pixel = png.getpixel((x * 8, y * 8))
+
+            bit = None
+            if pixel == RED:
+                bit = 1
+            elif pixel == GREEN:
+                bit = 0
+            else:
+                print(f"unsupported pixel in collision map {pixel}", file=sys.stderr)
+                return
+
+            bits.append(bit)
+            if len(bits) == 8:
+                byte = sum([bit << i for i, bit in enumerate(bits)])
+                out_bytes.append(byte)
+                bits = []
+
+    lines = []
+    for line_no in range(0, len(out_bytes), 16):
+        line = out_bytes[line_no : line_no + 16]
+        lines.append("    DB " + ", ".join(["$%02X" % b for b in line]))
+
+    section = pathlib.Path(in_path).name.replace("_coll.png", "")
+    all_lines = "\n".join(lines)
+
+    with open(out_path, "wb") as outf:
+        outf.write(
+            f"""SECTION "{section.upper()} MAP", ROM0
+
+; Values are provided in tiles
+DEF {section}_width  EQU {png.width // 8}
+DEF {section}_height EQU {png.height // 8}
+
+{section}_collision_map::
+{all_lines}
+""".encode(
+                "utf-8"
+            )
+        )
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser("generate_coll_map")
+    parser.add_argument("-o", "--output", required=True)
+    parser.add_argument("png")
+
+    args = parser.parse_args()
+    generate_coll_map(args.png, args.output)
+
+
+if __name__ == "__main__":
+    main()

src/player.s

@@ -9,7 +9,7 @@ playerWorldY: dw
 Section "Player Code", ROM0
 
 spriteData:
-    INCBIN "png/player.2bpp"
+    INCBIN "png/sprite/player.2bpp"
 
 DEF SPRITE_IDX EQU 32
 DEF SPRITE_WIDTH EQU 2