Load sprites

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/features/map/vswap_parser.dart

@@ -39,4 +39,65 @@ class VswapParser {
 
     return textures;
   }
+
+  /// Extracts the compiled scaled sprites from VSWAP.WL1
+  static List<Matrix<int>> parseSprites(ByteData vswap) {
+    int chunks = vswap.getUint16(0, Endian.little);
+    int spriteStart = vswap.getUint16(2, Endian.little);
+    int soundStart = vswap.getUint16(4, Endian.little);
+
+    List<int> offsets = [];
+    for (int i = 0; i < chunks; i++) {
+      offsets.add(vswap.getUint32(6 + (i * 4), Endian.little));
+    }
+
+    List<Matrix<int>> sprites = [];
+
+    // Sprites are located between the walls and the sounds
+    for (int i = spriteStart; i < soundStart; i++) {
+      int offset = offsets[i];
+      if (offset == 0) continue; // Some chunks are empty placeholders
+
+      // Initialize the 64x64 grid with 255 (The Magenta Transparency Color!)
+      Matrix<int> sprite = List.generate(64, (_) => List.filled(64, 255));
+
+      int leftPix = vswap.getUint16(offset, Endian.little);
+      int rightPix = vswap.getUint16(offset + 2, Endian.little);
+
+      // Read the offsets for each vertical column of the sprite
+      List<int> colOffsets = [];
+      for (int x = leftPix; x <= rightPix; x++) {
+        colOffsets.add(
+          vswap.getUint16(offset + 4 + ((x - leftPix) * 2), Endian.little),
+        );
+      }
+
+      for (int x = leftPix; x <= rightPix; x++) {
+        int colOffset = colOffsets[x - leftPix];
+        if (colOffset == 0) continue;
+
+        int cmdOffset = offset + colOffset;
+
+        // Execute the column drawing commands
+        while (true) {
+          int endY = vswap.getUint16(cmdOffset, Endian.little);
+          if (endY == 0) break; // 0 marks the end of the column
+          endY ~/= 2; // Wolf3D stores Y coordinates multiplied by 2
+
+          int pixelOfs = vswap.getUint16(cmdOffset + 2, Endian.little);
+
+          int startY = vswap.getUint16(cmdOffset + 4, Endian.little);
+          startY ~/= 2;
+
+          for (int y = startY; y < endY; y++) {
+            // The Carmack 286 Hack: pixelOfs + y gives the exact byte address!
+            sprite[x][y] = vswap.getUint8(offset + pixelOfs + y);
+          }
+          cmdOffset += 6; // Move to the next 6-byte instruction
+        }
+      }
+      sprites.add(sprite);
+    }
+    return sprites;
+  }
 }

lib/features/map/wolf_map.dart

@@ -8,9 +8,14 @@ class WolfMap {
   /// The fully parsed and decompressed levels from the game files.
   final List<WolfLevel> levels;
   final List<Matrix<int>> textures;
+  final List<Matrix<int>> sprites;
 
   // A private constructor so we can only instantiate this from the async loader
-  WolfMap._(this.levels, this.textures);
+  WolfMap._(
+    this.levels,
+    this.textures,
+    this.sprites,
+  );
 
   /// Asynchronously loads the map files and parses them into a new WolfMap instance.
   static Future<WolfMap> load() async {
@@ -22,8 +27,13 @@ class WolfMap {
     // 2. Parse the data using the parser we just built
     final parsedLevels = WolfMapParser.parseMaps(mapHead, gameMaps);
     final parsedTextures = VswapParser.parseWalls(vswap);
+    final parsedSprites = VswapParser.parseSprites(vswap);
 
     // 3. Return the populated instance!
-    return WolfMap._(parsedLevels, parsedTextures);
+    return WolfMap._(
+      parsedLevels,
+      parsedTextures,
+      parsedSprites,
+    );
   }
 }