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ParkanPlayground/Msh0x04.cs

@@ -0,0 +1,54 @@
+using NResLib;
+
+namespace ParkanPlayground;
+
+/// <summary>
+/// MSH-компонент 0x04: упакованные нормали вершин. clamp(component / 127.0, -1..1).
+/// </summary>
+public static class Msh0x04
+{
+    public static List<Msh04Normal> ReadComponent(FileStream mshFs, NResArchive archive)
+    {
+        var entry = archive.Files.FirstOrDefault(x => x.FileType == "04 00 00 00");
+
+        if (entry is null)
+        {
+            throw new Exception("Archive doesn't contain file (04)");
+        }
+
+        if (entry.ElementSize != 4)
+        {
+            throw new Exception("Packed normals file (04) element size is not 4");
+        }
+
+        if (entry.FileLength % entry.ElementSize != 0)
+        {
+            throw new Exception("Packed normals component (0x04) payload size is not divisible by element size");
+        }
+
+        var data = new byte[entry.FileLength];
+        mshFs.Seek(entry.OffsetInFile, SeekOrigin.Begin);
+        mshFs.ReadExactly(data, 0, data.Length);
+
+        var elements = new List<Msh04Normal>(entry.FileLength / entry.ElementSize);
+        for (var i = 0; i < entry.FileLength / entry.ElementSize; i++)
+        {
+            var offset = i * 4;
+            elements.Add(new Msh04Normal(
+                unchecked((sbyte)data[offset + 0]),
+                unchecked((sbyte)data[offset + 1]),
+                unchecked((sbyte)data[offset + 2]),
+                unchecked((sbyte)data[offset + 3])));
+        }
+
+        return elements;
+    }
+}
+
+/// <summary>Упакованная нормаль: четыре int8-компоненты (length = 4).</summary>
+/// <param name="X">[0x00..0x01] X-компонента.</param>
+/// <param name="Y">[0x01..0x02] Y-компонента.</param>
+/// <param name="Z">[0x02..0x03] Z-компонента.</param>
+/// <param name="W">[0x03..0x04] W-компонента.</param>
+public readonly record struct Msh04Normal(sbyte X, sbyte Y, sbyte Z, sbyte W)
+;