Figured out how to include some missing parts of TSTLT models, though these new parts don't render correctly at all yet.

Author: MeltyPlayer

FinModelUtility/Games/MarioArtist/MarioArtist/src/010/tstlt.bt

@@ -430,11 +430,14 @@ typedef struct (uint fSegmentOffset) {
 typedef struct (uint fSegmentOffset) {
     uint meshSegmentedAddresses[4] <bgcolor=COLOR_OFFSET>;
 
-    local uint firstMeshSegmentedAddress = meshSegmentedAddresses[0];
-    if (firstMeshSegmentedAddress != 0) {
-        local uint meshOffset = fSegmentOffset + (firstMeshSegmentedAddress & 0xffffff);
+    local uint meshI;
+    local uint meshOffset;
+    local uint tempOffset;
+    for (meshI = 0; meshI < 4; ++meshI) {
+        meshOffset = fSegmentOffset + (meshSegmentedAddresses[meshI] & 0xffffff);;
+        
         if (meshOffset < FileSize()) {
-            local uint tempOffset = FTell();
+            tempOffset = FTell();
             FSeek(meshOffset);
             uint firstMeshUint;
             if (firstMeshUint == 0) {

FinModelUtility/Games/MarioArtist/MarioArtist/src/api/TstltModelLoader.cs

@@ -619,9 +619,6 @@ private static IReadOnlyList<IMesh> TryToAddChosenPart0Tuple_(
       var (meshSegmentedAddress,
           vertexDlSegmentedAddress,
           primitiveDlSegmentedAddress) = tuples[i];
-      if (primitiveDlSegmentedAddress == 0) {
-        continue;
-      }
 
       if (meshSegmentedAddress != 0 &&
           n64Hardware.Memory
@@ -644,7 +641,20 @@ private static IReadOnlyList<IMesh> TryToAddChosenPart0Tuple_(
         var imageSectionOffset = sbr.ReadUInt32();
         var vertexSectionOffset = sbr.ReadUInt32();
 
-        sbr.Position = meshBaseOffset + 4 * 14;
+        sbr.Position = meshBaseOffset + 4 * 12;
+        var primitiveDlOffset = sbr.ReadUInt32();
+        var vertexDlOffset = sbr.ReadUInt32();
+
+        // Not really sure why, but sometimes these aren't set.
+        if (primitiveDlSegmentedAddress == 0) {
+          primitiveDlSegmentedAddress
+              = meshSegmentedAddress + primitiveDlOffset;
+        }
+
+        if (vertexDlSegmentedAddress == 0) {
+          vertexDlSegmentedAddress = meshSegmentedAddress + vertexDlOffset;
+        }
+
         var imageCount = sbr.ReadUInt16();
 
         n64Hardware.Memory.SetSegment(
@@ -687,6 +697,10 @@ private static IReadOnlyList<IMesh> TryToAddChosenPart0Tuple_(
                          : chosenPart0.Pattern0MaterialType);
       }
 
+      if (primitiveDlSegmentedAddress == 0) {
+        continue;
+      }
+
       n64Hardware.Rsp.CullingMode
           = GetCullingModeForChosenPartId_(chosenPart0.Id);