From e80af7bdda47a3deab7306e91423188ea9bc4d7c Mon Sep 17 00:00:00 2001
From: Luke Hubmayer-Werner <ld.hubmayer.werner@gmail.com>
Date: Sat, 12 Aug 2023 23:12:28 +0930
Subject: [PATCH] Make battle tilemap code more idiomatic

---
 scripts/loaders/snes/battle_bgs.gd | 61 +++++++++++++++---------------
 1 file changed, 31 insertions(+), 30 deletions(-)

diff --git a/scripts/loaders/snes/battle_bgs.gd b/scripts/loaders/snes/battle_bgs.gd
index aab68b4..107317d 100644
--- a/scripts/loaders/snes/battle_bgs.gd
+++ b/scripts/loaders/snes/battle_bgs.gd
@@ -1,43 +1,38 @@
 extends Node
-const LENGTH := 0x500 / 2  # Expanded length 0x500, RLE step produces 0x280 bytes
+const LENGTH := 0x500 / 2  # Expanded length 0x500, RLE step produces 0x280 tile mappings
 
-func decompress_battle_tilemap(buffer: StreamPeerBuffer) -> PoolByteArray:
+func decompress_battle_tilemap(buffer: StreamPeerBuffer) -> Array:
 	# Decompresses the tilemap for a battle background.
 	# Battle BGs use a type of RLE with 2byte repeat and 1byte incremental repeat.
-	var o1 := PoolByteArray()
-	while len(o1) < LENGTH:
+	var mappings := []
+	while len(mappings) < LENGTH:
 		var byte := buffer.get_u8()
 		if byte != 0xFF:
-			o1.append(byte)
+			mappings.append(TileMapping.from_battle_byte(byte))
 		else:  # Byte begins a repeat code
 			var repeat_code := buffer.get_u8()
 			var repeat := repeat_code & 0x3F
 			byte = buffer.get_u8()
 			if repeat_code & 0x80:  # Repeat 2 tiles
-				var b := buffer.get_u8()
+				var byte2 := buffer.get_u8()
 				for i in repeat:
-					o1.append(byte)
-					o1.append(b)
+					mappings.append(TileMapping.from_battle_byte(byte))
+					mappings.append(TileMapping.from_battle_byte(byte2))
 			else:  # Incremental repeat
 				var inc := buffer.get_u8()
 				if repeat_code & 0x40:  # Negative increment
 					inc = -inc
 				for i in repeat:
-					o1.append(byte + (inc * i))
-	var output := PoolByteArray()
-	for byte in o1:
-		# 0bYXXXXXXX -> 0b0000YY00_1XXXXXXX
-		output.append(byte | 0x80)
-		output.append(((1+(byte>>7)) << 2) & 0xDF)
-	return output
+					mappings.append(TileMapping.from_battle_byte(byte))
+					byte += inc
+	return mappings
 
-func apply_battle_tilemap_flips(buffer: StreamPeerBuffer, id: int, tilemap: PoolByteArray):
+func apply_battle_tilemap_flips(buffer: StreamPeerBuffer, id: int, tilemap: Array):
 	if id==0xFF:
-		return tilemap
+		return
 	buffer.seek(0x14C736+(id*2))
 	var ptr := 0x140000 + buffer.get_u16()
 	buffer.seek(ptr)
-	var output = tilemap
 	var tile_i := 0
 	while tile_i < LENGTH:
 		var a := buffer.get_u8()
@@ -46,22 +41,28 @@ func apply_battle_tilemap_flips(buffer: StreamPeerBuffer, id: int, tilemap: Pool
 		else:
 			# Each bit is a tile, 1 means flip horizontally
 			for b in range(7, -1, -1):
-				var tile_flip := (a>>b) & 0x01
-				output[(tile_i*2)+1] |= tile_flip << 6  # Set the OAM flag for this tile
+				tilemap[tile_i].h_flip = bool((a>>b) & 0x01)
 				tile_i += 1
-	return output
 
 
 class TileMapping:
 	var tile_index: int
 	var palette: int
-	var priority: int
-	var h_flip: int
-	var v_flip: int
+	var priority: bool
+	var h_flip: bool
+	var v_flip: bool
 
-	func _init(w: int):
-		self.tile_index = w & 0x03FF
-		self.palette = (w & 0x1C00) >> 10
-		self.priority = (w & 0x2000) >> 13
-		self.h_flip = (w & 0x4000) >> 14
-		self.v_flip = (w & 0x8000) >> 15
+	static func from_tilemap_word(w: int) -> TileMapping:
+		var t := TileMapping.new()
+		t.tile_index = w & 0x03FF
+		t.palette = (w & 0x1C00) >> 10
+		t.priority = bool(w & 0x2000)
+		t.h_flip = bool(w & 0x4000)
+		t.v_flip = bool(w & 0x8000)
+		return t
+
+	static func from_battle_byte(b: int) -> TileMapping:
+		var t := TileMapping.new()
+		t.tile_index = b | 0x80
+		t.palette = 1 + (b >> 7)
+		return t