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Source/Engine/Graphics/RenderTargetPool.cpp

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+#include "RenderTargetPool.h"
+#include "GPUDevice.h"
+#include "Engine/Engine/Engine.h"
+
+struct Entry
+{
+    bool IsOccupied;
+    GPUTexture* RT;
+    uint64 LastFrameTaken;
+    uint64 LastFrameReleased;
+    uint32 DescriptionHash;
+};
+
+namespace
+{
+    Array<Entry> TemporaryRTs(64);
+}
+
+void RenderTargetPool::Flush(bool force)
+{
+    const uint64 framesOffset = 10;
+    const uint64 maxReleaseFrame = Engine::FrameCount - framesOffset;
+    force |= Engine::ShouldExit();
+
+    for (int32 i = 0; i < TemporaryRTs.Count(); i++)
+    {
+        auto& tmp = TemporaryRTs[i];
+
+        if (!tmp.IsOccupied && (force || (tmp.LastFrameReleased < maxReleaseFrame)))
+        {
+            // Release
+            tmp.RT->DeleteObjectNow();
+            TemporaryRTs.RemoveAt(i);
+            i--;
+
+            if (TemporaryRTs.IsEmpty())
+                break;
+        }
+    }
+}
+
+GPUTexture* RenderTargetPool::Get(const GPUTextureDescription& desc)
+{
+    // Find free render target with the same properties
+    const uint32 descHash = GetHash(desc);
+    for (int32 i = 0; i < TemporaryRTs.Count(); i++)
+    {
+        auto& tmp = TemporaryRTs[i];
+
+        if (!tmp.IsOccupied && tmp.DescriptionHash == descHash)
+        {
+            ASSERT(tmp.RT);
+
+            // Mark as used
+            tmp.IsOccupied = true;
+            tmp.LastFrameTaken = Engine::FrameCount;
+            return tmp.RT;
+        }
+    }
+
+#if !BUILD_RELEASE
+    if (TemporaryRTs.Count() > 2000)
+    {
+        LOG(Fatal, "Too many textures allocated in RenderTargetPool. Know your limits, sir!");
+        return nullptr;
+    }
+#endif
+
+    // Create new rt
+    const String name = TEXT("TemporaryRT_") + StringUtils::ToString(TemporaryRTs.Count());
+    auto newRenderTarget = GPUDevice::Instance->CreateTexture(name);
+    if (newRenderTarget->Init(desc))
+    {
+        LOG(Error, "Cannot create temporary render target. Description: {0}", desc.ToString());
+        return nullptr;
+    }
+
+    // Create temporary rt entry
+    Entry entry;
+    entry.IsOccupied = true;
+    entry.LastFrameReleased = 0;
+    entry.LastFrameTaken = Engine::FrameCount;
+    entry.RT = newRenderTarget;
+    entry.DescriptionHash = descHash;
+    TemporaryRTs.Add(entry);
+
+    return newRenderTarget;
+}
+
+void RenderTargetPool::Release(GPUTexture* rt)
+{
+    if (!rt)
+        return;
+
+    for (int32 i = 0; i < TemporaryRTs.Count(); i++)
+    {
+        auto& tmp = TemporaryRTs[i];
+
+        if (tmp.RT == rt)
+        {
+            // Mark as free
+            ASSERT(tmp.IsOccupied);
+            tmp.IsOccupied = false;
+            tmp.LastFrameReleased = Engine::FrameCount;
+            return;
+        }
+    }
+
+    LOG(Error, "Trying to release temporary render target which has not been registred in service!");
+}