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Source/Engine/Content/Upgraders/MaterialInstanceUpgrader.h

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "BinaryAssetUpgrader.h"
+#include "Engine/Core/Core.h"
+#include "Engine/Platform/Platform.h"
+#include "Engine/Serialization/MemoryReadStream.h"
+#include "Engine/Serialization/MemoryWriteStream.h"
+
+/// <summary>
+/// Material Instance Upgrader
+/// </summary>
+/// <seealso cref="BinaryAssetUpgrader" />
+class MaterialInstanceUpgrader : public BinaryAssetUpgrader
+{
+public:
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="MaterialInstanceUpgrader"/> class.
+    /// </summary>
+    MaterialInstanceUpgrader()
+    {
+        static const Upgrader upgraders[] =
+        {
+            { 1, 3, &Upgrade_1_To_3 },
+            { 3, 4, &Upgrade_3_To_4 },
+        };
+        setup(upgraders, ARRAY_COUNT(upgraders));
+    }
+
+private:
+
+    // ============================================
+    //                  Version 4:
+    // Designed: 5/18/2017
+    // Custom Data: not used
+    // Chunk 0:
+    //   - Parent material: Guid
+    //   - Material Params
+    // ============================================
+    //                  Version 3:
+    // Designed: 1/24/2016
+    // Custom Data: not used
+    // Chunk 0:
+    //   - Magic Code: int32 ('MI\0@', 1073760589)
+    //   - Version: int32
+    //   - Parent material: Guid
+    //   - Material Params
+    //   - Ending char: 1 byte (~)
+    // ============================================
+
+    static bool Upgrade_1_To_3(AssetMigrationContext& context)
+    {
+        ASSERT(context.Input.SerializedVersion == 1 && context.Output.SerializedVersion == 3);
+
+        auto chunk = context.Input.Header.Chunks[0];
+        if (chunk == nullptr || chunk->IsMissing())
+        {
+            LOG(Warning, "Missing material instance data chunk.");
+            return true;
+        }
+        if (context.AllocateChunk(0))
+            return true;
+        context.Output.Header.Chunks[0]->Data.Copy(chunk->Data);
+
+        return false;
+    }
+
+    static bool Upgrade_3_To_4(AssetMigrationContext& context)
+    {
+        ASSERT(context.Input.SerializedVersion == 3 && context.Output.SerializedVersion == 4);
+
+        auto chunk = context.Input.Header.Chunks[0];
+        if (chunk == nullptr || chunk->IsMissing())
+        {
+            LOG(Warning, "Missing material instance data chunk.");
+            return true;
+        }
+        if (context.AllocateChunk(0))
+            return true;
+        MemoryReadStream inStream(chunk->Data.Get(), chunk->Data.Length());
+        MemoryWriteStream outStream(chunk->Size());
+
+        // Header
+        int32 magicCode;
+        inStream.ReadInt32(&magicCode);
+        int32 version;
+        inStream.ReadInt32(&version);
+        if (magicCode != 1073760589 || version != 3)
+        {
+            LOG(Warning, "Invalid material instance header.");
+            return true;
+        }
+
+        // Parent material + Params
+        // TODO: add tool function to copy stream -> stream
+        while (inStream.CanRead())
+        {
+            byte b = inStream.ReadByte();
+            outStream.WriteByte(b);
+        }
+        context.Output.Header.Chunks[0]->Data.Copy(outStream.GetHandle(), outStream.GetPosition());
+
+        return false;
+    }
+};