87 lines
2.6 KiB
C++
87 lines
2.6 KiB
C++
// Copyright (c) Wojciech Figat. All rights reserved.
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#pragma once
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#include "Engine/Core/Math/Matrix.h"
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#include "Engine/Core/Collections/Array.h"
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#include "Engine/Graphics/Config.h"
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GPU_CB_STRUCT(OcclusionCullingData {
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Matrix ViewProjectionMatrix;
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float RTSizeX;
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float RTSizeY;
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float MaxMipLevel;
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uint32 CullCount;
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});
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/// <summary>
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/// Utility for occlusion culling implementations to manage stable CullingId for objects with state tracking (over multiple frames).
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/// </summary>
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template<typename Item>
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class OcclusionCullingItems : public Array<Item>
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{
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private:
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volatile int64 _freeItemsCount = 0;
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volatile int64 _newItemsCount = 0;
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Array<uint32> _freeItems;
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Array<uint32> _freedItems;
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public:
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void BeginFrame()
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{
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// Remove used free items
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_freeItems.Resize(Math::Max((int32)_freeItemsCount, 0));
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// Put back freed items to the free list
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_freeItems.Add(_freedItems);
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_freedItems.Clear();
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// Allocate new items (as requested during the previous frame)
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if (_newItemsCount > 0)
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{
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int32 itemsStart = this->Count(), count = (int32)_newItemsCount, freeStart = _freeItems.Count();
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if (itemsStart == 0)
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count++; // 0 is invalid for cullingId
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this->AddZeroed(count);
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_freeItems.AddUninitialized(count);
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for (int32 i = 0; i < count; i++)
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_freeItems.Get()[freeStart + i] = itemsStart + i;
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if (itemsStart == 0)
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_freeItems.RemoveAt(0); // 0 is invalid for cullingId
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_newItemsCount = 0;
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}
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_freeItemsCount = _freeItems.Count();
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}
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bool GetCullingId(uint32& cullingId)
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{
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// Check if object doesn't have ID assigned yet
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if (cullingId == 0 || cullingId >= (uint32)this->Count())
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{
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int64 freeIndex = Platform::InterlockedDecrement(&_freeItemsCount);
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if (freeIndex >= 0)
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{
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// Use the ID from the free list
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ASSERT_LOW_LAYER(freeIndex < _freeItems.Count());
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cullingId = _freeItems.Get()[freeIndex];
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}
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else
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{
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// Count space needed to contain all objects (for the next frame)
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Platform::InterlockedIncrement(&_newItemsCount);
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return true;
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}
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}
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return false;
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}
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void FreeObject(uint32 cullingId)
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{
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ASSERT(cullingId > 0 && cullingId < (uint32)this->Count());
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_freedItems.Add(cullingId);
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auto& item = this->Get()[cullingId];
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Platform::MemoryClear(&item, sizeof(item));
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}
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};
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