ParticleCurveTexture.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
/*==============================================================================
    ParticleCurveTexture.h: Texture used to hold particle curves.
==============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "RenderResource.h"
 
extern const int32 GParticleCurveTextureSizeX;
extern const int32 GParticleCurveTextureSizeY;
 
/*------------------------------------------------------------------------------
    Texel allocator.
------------------------------------------------------------------------------*/
 
struct FTexelAllocation
{
    uint16 X;
    uint16 Y;
    uint16 Size;
 
    FTexelAllocation()
        : X(0)
        , Y(0)
        , Size(0)
    {
    }
};
 
class FTexelAllocator
{
public:
 
    FTexelAllocator( const int32 InTextureSizeX, const int32 InTextureSizeY );
 
    ~FTexelAllocator();
 
    FTexelAllocation Allocate( int32 Size );
 
    void Free( FTexelAllocation Allocation );
 
private:
 
    struct FBlock
    {
        FBlock* Next;
        uint16 Begin;
        uint16 Size;
    };
 
    FBlock* GetBlock();
 
    void ReturnBlock( FBlock* Block );
 
    TArray<FBlock*> FreeBlocks;
    FBlock* BlockPool;
    int32 BlockCount;
    int32 TextureSizeX;
    int32 TextureSizeY;
    int32 FreeTexels;
};
 
/*-----------------------------------------------------------------------------
    A texture for storing curve samples on the GPU.
-----------------------------------------------------------------------------*/
 
struct FCurveSamples
{
    FColor* Samples;
    FTexelAllocation TexelAllocation;
};
 
class FParticleCurveTexture : public FRenderResource
{
public:
 
    FParticleCurveTexture();
 
    virtual void InitRHI(FRHICommandListBase& RHICmdList) override;
 
    virtual void ReleaseRHI() override;
 
    FTexelAllocation AddCurve( const TArray<FColor>& CurveSamples );
 
    void RemoveCurve( FTexelAllocation TexelAllocation );
 
    FVector4f ComputeCurveScaleBias( FTexelAllocation TexelAllocation );
 
    FRHITexture* GetCurveTexture() { return CurveTextureRHI; }
 
    void SubmitPendingCurves();
 
private:
    FTextureRHIRef CurveTextureRHI;
    FTexelAllocator TexelAllocator;
    TArray<FCurveSamples> PendingCurves;
};
 
extern TGlobalResource<FParticleCurveTexture> GParticleCurveTexture;