How RenderTexture_RenderThread work?

I am writing a stere rendering plugin? I see the sampleHMD and OSVR etc , but i don’t know when or how to let RenderTexture_RenderThread works . As you I can see MyCode:
void FKDXStereHMD::RenderTexture_RenderThread(FRHICommandListImmediate& RHICmdList, FTexture2DRHIParamRef BackBuffer, FTexture2DRHIParamRef SrcTexture) const
{
//check(IsInRenderingThread());
//const uint32 viewportWidth = BackBuffer->GetSizeX();
//const uint32 viewportHeight = BackBuffer->GetSizeY();

//FGraphicsPipelineStateInitializer GraphicsPSOInit;
//SetRenderTarget(RHICmdList, BackBuffer, FTextureRHIRef());
//RHICmdList.ApplyCachedRenderTargets(GraphicsPSOInit);
//RHICmdList.SetViewport(0, 0, 0, viewportWidth, viewportHeight, 1.0f);
//GraphicsPSOInit.BlendState = TStaticBlendState<>::GetRHI();
//GraphicsPSOInit.RasterizerState = TStaticRasterizerState<>::GetRHI();
//GraphicsPSOInit.DepthStencilState = TStaticDepthStencilState<false, CF_Always>::GetRHI();
//const auto featureLevel = GMaxRHIFeatureLevel;
//auto shaderMap = GetGlobalShaderMap(featureLevel);
//TShaderMapRef<FScreenVS> vertexShader(shaderMap);
//TShaderMapRef<FScreenPS> pixelShader(shaderMap);
//GraphicsPSOInit.BoundShaderState.VertexDeclarationRHI = RendererModule->GetFilterVertexDeclaration().VertexDeclarationRHI;
//GraphicsPSOInit.BoundShaderState.VertexShaderRHI = GETSAFERHISHADER_VERTEX(*vertexShader);
//GraphicsPSOInit.BoundShaderState.PixelShaderRHI = GETSAFERHISHADER_PIXEL(*pixelShader);
//GraphicsPSOInit.PrimitiveType = PT_TriangleList;
//SetGraphicsPipelineState(RHICmdList, GraphicsPSOInit);
//pixelShader->SetParameters(RHICmdList, TStaticSamplerState<SF_Bilinear>::GetRHI(), SrcTexture);
//RendererModule->DrawRectangle(
//	RHICmdList,
//	0, 0, // X, Y
//	viewportWidth, viewportHeight, // SizeX, SizeY
//	0.0f, 0.0f, // U, V
//	1.0f, 1.0f, // SizeU, SizeV
//	FIntPoint(viewportWidth, viewportHeight), // TargetSize
//	FIntPoint(1, 1), // TextureSize
//	*vertexShader,
//	EDRF_Default);

KDXLog(TEXT("RenderTexture_RenderThread:%s"), *FString("True"));

}