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Source/Engine/Streaming/StreamableResource.h

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Core/Types/DateTime.h"
+#include "Engine/Core/Collections/SamplesBuffer.h"
+#include "Config.h"
+
+class StreamingGroup;
+class Task;
+
+/// <summary>
+/// Base class for all resource types that can be dynamically streamed.
+/// </summary>
+class FLAXENGINE_API StreamableResource
+{
+protected:
+
+    StreamingGroup* _group;
+    bool _isDynamic, _isStreaming;
+    StreamingQuality _streamingQuality;
+
+    StreamableResource(StreamingGroup* group);
+    ~StreamableResource();
+
+public:
+
+    /// <summary>
+    /// Gets resource group
+    /// </summary>
+    /// <returns>Streaming Group</returns>
+    FORCE_INLINE StreamingGroup* GetGroup() const
+    {
+        return _group;
+    }
+
+    /// <summary>
+    /// Gets value indicating whenever resource can be used in dynamic streaming (otherwise use always the best quality)
+    /// </summary>
+    /// <returns>Is dynamic streamable</returns>
+    FORCE_INLINE bool IsDynamic() const
+    {
+#if ENABLE_RESOURCES_DYNAMIC_STREAMING
+        return _isDynamic;
+#else
+		return false;
+#endif
+    }
+
+    /// <summary>
+    /// Gets resource streaming quality level
+    /// </summary>
+    /// <returns>Streaming Quality level</returns>
+    FORCE_INLINE StreamingQuality GetStreamingQuality() const
+    {
+        return _streamingQuality;
+    }
+
+    /// <summary>
+    /// Gets resource maximum residency level.
+    /// </summary>
+    /// <returns>Residency</returns>
+    virtual int32 GetMaxResidency() const = 0;
+
+    /// <summary>
+    /// Gets resource current residency level.
+    /// </summary>
+    /// <returns>Residency</returns>
+    virtual int32 GetCurrentResidency() const = 0;
+
+    /// <summary>
+    /// Gets resource allocated residency level.
+    /// </summary>
+    /// <returns>Residency</returns>
+    virtual int32 GetAllocatedResidency() const = 0;
+
+    /// <summary>
+    /// Gets resource target residency level.
+    /// </summary>
+    /// <returns>Residency</returns>
+    int32 GetTargetResidency() const
+    {
+        return Streaming.TargetResidency;
+    }
+
+    /// <summary>
+    /// Gets a value indicating whether this resource has been allocated. 
+    /// </summary>
+    FORCE_INLINE bool IsAllocated() const
+    {
+        return GetAllocatedResidency() != 0;
+    }
+
+public:
+
+    /// <summary>
+    /// Determines whether this instance can be updated. Which means: no async streaming, no pending action in background.
+    /// </summary>
+    /// <returns><c>true</c> if this instance can be updated; otherwise, <c>false</c>.</returns>
+    virtual bool CanBeUpdated() const = 0;
+
+    /// <summary>
+    /// Updates the resource allocation to the given residency level. May not be updated now but in an async operation.
+    /// </summary>
+    /// <param name="residency">The target allocation residency.</param>
+    /// <returns>Async task that updates resource allocation or null if already done it. Warning: need to call task start to perform allocation.</returns>
+    virtual Task* UpdateAllocation(int32 residency) = 0;
+
+    /// <summary>
+    /// Creates streaming task (or tasks sequence) to perform resource streaming for the desire residency level.
+    /// </summary>
+    /// <param name="residency">The target residency.</param>
+    /// <returns>Async task or tasks that update resource residency level. Must be preceded with UpdateAllocation call.</returns>
+    virtual Task* CreateStreamingTask(int32 residency) = 0;
+
+public:
+
+    // Streaming Manager cached variables
+    struct StreamingCache
+    {
+        /// <summary>
+        /// The minimum usage distance since last update (eg. mesh draw distance from camera).
+        /// Used to calculate resource quality.
+        /// </summary>
+        //float MinDstSinceLastUpdate;
+
+        DateTime LastUpdate;
+        int32 TargetResidency;
+        DateTime TargetResidencyChange;
+        SamplesBuffer<StreamingQuality, 5> QualitySamples;
+
+        StreamingCache()
+        //: MinDstSinceLastUpdate(MAX_float)
+            : LastUpdate(0)
+            , TargetResidency(0)
+            , TargetResidencyChange(0)
+        {
+        }
+    };
+
+    StreamingCache Streaming;
+
+    /// <summary>
+    /// Requests the streaming update for this resource during next streaming manager update.
+    /// </summary>
+    void RequestStreamingUpdate()
+    {
+        Streaming.LastUpdate.Ticks = 0;
+    }
+
+protected:
+
+    void startStreaming(bool isDynamic);
+    void stopStreaming();
+};