Fix wall texture loading and improve loading times

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

packages/wolf_3d_dart/lib/src/data/wl_parser.dart

@@ -196,13 +196,25 @@ abstract class WLParser {
   // --- Private Helpers ---
 
   static Sprite _parseWallChunk(ByteData vswap, int offset) {
-    final pixels = Uint8List(64 * 64);
-    for (int x = 0; x < 64; x++) {
-      for (int y = 0; y < 64; y++) {
-        // Flat 1D index: x * 64 + y
-        pixels[x * 64 + y] = vswap.getUint8(offset + (x * 64) + y);
-      }
+    // --- SAFETY CHECK ---
+    // Prevent crashes from corrupted VSWAP offsets or dummy EOF chunks
+    if (offset + 4096 > vswap.lengthInBytes) {
+      // Return a blank transparent sprite if the data is invalid
+      return Sprite(Uint8List(4096)..fillRange(0, 4096, 255));
     }
+
+    // --- OPTIMIZATION ---
+    // Instead of looping 4,096 times, we slice the exact memory block instantly.
+    // Because Wolf3D walls are natively stored in column-major order on disk,
+    // they perfectly match our 1D Sprite array layout without any math!
+    final rawView = vswap.buffer.asUint8List(
+      vswap.offsetInBytes + offset,
+      4096,
+    );
+
+    // Create a new Uint8List copy so we don't hold the entire file in memory
+    final pixels = Uint8List.fromList(rawView);
+
     return Sprite(pixels);
   }
 
@@ -225,7 +237,6 @@ abstract class WLParser {
     }
 
     for (int x = leftPix; x <= rightPix; x++) {
-      // REVERTED to your original, correct math!
       int colOffset = vswap.getUint16(
         offset + 4 + ((x - leftPix) * 2),
         Endian.little,
@@ -249,7 +260,6 @@ abstract class WLParser {
       if (endY == 0) break;
       endY ~/= 2;
 
-      // THE FIX: This MUST be a signed integer (getInt16) to handle DOS wraparound
       int pixelOfs = vswap.getInt16(cmdOffset + 2, Endian.little);
 
       int startY = vswap.getUint16(cmdOffset + 4, Endian.little);