From efc9d163376bc02f5b2862c5da74e97491582050 Mon Sep 17 00:00:00 2001
From: fallenoak <git@fallenoak.me>
Date: Sun, 31 Dec 2023 15:54:56 -0600
Subject: [PATCH] fix(map): correct various splat issues when loading map
 chunks

---
 src/lib/map/MapArea.ts | 41 ++++++++++++++++++++++++-----------------
 src/lib/map/const.ts   |  1 +
 2 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/src/lib/map/MapArea.ts b/src/lib/map/MapArea.ts
index 1db7dae..8072cf9 100644
--- a/src/lib/map/MapArea.ts
+++ b/src/lib/map/MapArea.ts
@@ -75,23 +75,30 @@ class MapArea {
     for (const { textureId, properties, alphaOffset, effectId } of chunkData.get('MCLY') ?? []) {
       const texture = textures[textureId];
 
-      // Normalize all MCAL splats into 8-bit depth splats
-      let splat: Uint8Array;
-      if (!alpha || alpha.length === 0) {
-        splat = null;
-      } else if (this.#layerSplatDepth === 4) {
-        const rawSplat = new Uint8Array(
-          alpha.buffer,
-          alpha.byteOffset + alphaOffset,
-          MAP_LAYER_SPLAT_SIZE / 2,
-        );
-        const needsFix = (chunkHeader.flags & MAP_CHUNK_FLAG.FIXED_LAYER_SPLAT) === 0;
-        splat = splat4To8(rawSplat, needsFix);
-      } else if (properties & MAP_LAYER_PROPERTY.SPLAT_COMPRESSED) {
-        const rawSplat = new Uint8Array(alpha.buffer, alpha.byteOffset, alphaOffset);
-        splat = splatCompressedTo8(rawSplat);
-      } else {
-        splat = new Uint8Array(alpha.buffer, alpha.byteOffset + alphaOffset, MAP_LAYER_SPLAT_SIZE);
+      let splat: Uint8Array = null;
+      const hasSplat = (properties & MAP_LAYER_PROPERTY.HAS_SPLAT) !== 0;
+
+      if (hasSplat && alpha && alpha.length > 0) {
+        // Normalize 4-bit and compressed splats into 8-bit depth splats
+
+        if (this.#layerSplatDepth === 4) {
+          const rawSplat = new Uint8Array(
+            alpha.buffer,
+            alpha.byteOffset + alphaOffset,
+            MAP_LAYER_SPLAT_SIZE / 2,
+          );
+          const needsFix = (chunkHeader.flags & MAP_CHUNK_FLAG.FIXED_LAYER_SPLAT) === 0;
+          splat = splat4To8(rawSplat, needsFix);
+        } else if (properties & MAP_LAYER_PROPERTY.SPLAT_COMPRESSED) {
+          const rawSplat = new Uint8Array(alpha.buffer, alpha.byteOffset + alphaOffset);
+          splat = splatCompressedTo8(rawSplat);
+        } else {
+          splat = new Uint8Array(
+            alpha.buffer,
+            alpha.byteOffset + alphaOffset,
+            MAP_LAYER_SPLAT_SIZE,
+          );
+        }
       }
 
       const layer = new MapLayer(texture, splat, effectId);
diff --git a/src/lib/map/const.ts b/src/lib/map/const.ts
index 2ba63b2..4774175 100644
--- a/src/lib/map/const.ts
+++ b/src/lib/map/const.ts
@@ -38,6 +38,7 @@ enum MAP_CHUNK_FLAG {
 }
 
 enum MAP_LAYER_PROPERTY {
+  HAS_SPLAT = 0x100,
   SPLAT_COMPRESSED = 0x200,
 }