animations and QOL

MshLib/Msh0x13.cs

@@ -0,0 +1,53 @@
+using System.Buffers.Binary;
+using NResLib;
+
+namespace MshLib;
+
+public static class Msh0x13
+{
+    public static Msh0x13Component ReadComponent(FileStream mshFs, NResArchive archive)
+    {
+        var entry = archive.Files.FirstOrDefault(x => x.FileType == "13 00 00 00");
+
+        if (entry is null)
+        {
+            throw new Exception("Archive doesn't contain animation map component (0x13)");
+        }
+
+        if (entry.ElementSize < 2)
+        {
+            throw new Exception("Animation map component (0x13) element size is too small");
+        }
+
+        var data = new byte[entry.FileLength];
+        mshFs.Seek(entry.OffsetInFile, SeekOrigin.Begin);
+        mshFs.ReadExactly(data, 0, data.Length);
+
+        var elementCount = checked((int)entry.ElementCount);
+        var entries = new List<MshAnimationMapEntry>(elementCount);
+        var span = data.AsSpan();
+        for (var i = 0; i < elementCount; i++)
+        {
+            var elementOffset = i * entry.ElementSize;
+            entries.Add(new MshAnimationMapEntry(
+                BinaryPrimitives.ReadUInt16LittleEndian(span.Slice(elementOffset, 2))));
+        }
+
+        return new Msh0x13Component(entry.ElementSize, entries)
+        {
+            MaxAnimationTime = entry.Magic1
+        };
+    }
+}
+
+public readonly record struct MshAnimationMapEntry(
+    ushort KeyframeIndex
+);
+
+public sealed record Msh0x13Component(
+    int ElementSize,
+    List<MshAnimationMapEntry> Entries
+)
+{
+    public int MaxAnimationTime { get; init; }
+}