61 lines
2.6 KiB
C++
61 lines
2.6 KiB
C++
// Copyright (c) Wojciech Figat. All rights reserved.
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#pragma once
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#include "../RendererPass.h"
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#include "Engine/Graphics/GPUPipelineStatePermutations.h"
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/// <summary>
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/// Bitonic Sort implementation using GPU compute shaders.
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/// It has a complexity of O(n*(log n)^2), which is inferior to most traditional sorting algorithms, but because GPUs have so many threads,
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/// and because each thread can be utilized, the algorithm can fully load the GPU, taking advantage of its high ALU and bandwidth capabilities.
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/// </summary>
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class BitonicSort : public RendererPass<BitonicSort>
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{
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private:
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AssetReference<Shader> _shader;
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GPUBuffer* _dispatchArgsBuffer = nullptr;
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GPUConstantBuffer* _cb;
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GPUShaderProgramCS* _indirectArgsCS;
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ComputeShaderPermutation<2> _preSortCS;
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GPUShaderProgramCS* _innerSortCS;
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GPUShaderProgramCS* _outerSortCS;
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GPUShaderProgramCS* _copyIndicesCS;
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public:
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/// <summary>
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/// Sorts the specified buffers of index-key pairs.
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/// </summary>
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/// <param name="context">The GPU context.</param>
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/// <param name="indicesBuffer">The sorting indices buffer with an index for each item (sequence of: 0, 1, 2, 3...). After sorting represents actual items order based on their keys. Valid for uint value types - used as RWBuffer.</param>
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/// <param name="keysBuffer">The sorting keys buffer with a sort value for each item (must match order of items in indicesBuffer). Valid for float value types - used as RWBuffer.</param>
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/// <param name="countBuffer">The buffer that contains a items counter value.</param>
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/// <param name="counterOffset">The offset into counter buffer to find count for this list. Must be a multiple of 4 bytes.</param>
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/// <param name="sortAscending">True to sort in ascending order (smallest to largest), otherwise false to sort in descending order.</param>
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/// <param name="maxElements">Optional upper limit of elements to sort. Cna be used to optimize indirect dispatches allocation. If non-zero, then it gets calculated based on the input item buffer size.</param>
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void Sort(GPUContext* context, GPUBuffer* indicesBuffer, GPUBuffer* keysBuffer, GPUBuffer* countBuffer, uint32 counterOffset, bool sortAscending, int32 maxElements = 0);
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public:
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// [RendererPass]
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String ToString() const override;
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bool Init() override;
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void Dispose() override;
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#if COMPILE_WITH_DEV_ENV
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void OnShaderReloading(Asset* obj)
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{
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_preSortCS.Clear();
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_innerSortCS = nullptr;
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_outerSortCS = nullptr;
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invalidateResources();
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}
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#endif
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protected:
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// [RendererPass]
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bool setupResources() override;
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};
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