SpriteIndexBuffer.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "RenderResource.h"
#include "RHI.h"
#include "RHICommandList.h"
 
template< uint32 NumSprites >
class FSpriteIndexBuffer : public FIndexBuffer
{
public:
    virtual void InitRHI(FRHICommandListBase& RHICmdList) override
    {
        const FRHIBufferCreateDesc CreateDesc =
            FRHIBufferCreateDesc::CreateIndex<uint16>(TEXT("FSpriteIndexBuffer"), 6 * NumSprites)
            .AddUsage(EBufferUsageFlags::Static)
            .SetInitialState(ERHIAccess::VertexOrIndexBuffer)
            .SetInitActionInitializer();
 
        TRHIBufferInitializer<uint16> Indices = RHICmdList.CreateBufferInitializer(CreateDesc);
 
        for (uint32 SpriteIndex = 0; SpriteIndex < NumSprites; ++SpriteIndex)
        {
            Indices[SpriteIndex*6 + 0] = SpriteIndex*4 + 0;
            Indices[SpriteIndex*6 + 1] = SpriteIndex*4 + 3;
            Indices[SpriteIndex*6 + 2] = SpriteIndex*4 + 2;
            Indices[SpriteIndex*6 + 3] = SpriteIndex*4 + 0;
            Indices[SpriteIndex*6 + 4] = SpriteIndex*4 + 1;
            Indices[SpriteIndex*6 + 5] = SpriteIndex*4 + 3;
        }
 
        IndexBufferRHI = Indices.Finalize();
    }
};