スワップチェインで切り替えようとしたんだけど、このコードでは上手くいかない… 真っ暗…
lpSwapChain[1]をlpSwapChain[0]に変えると正しく描画される。これじゃダメなんでしょうか？

D3DPresentParam.BackBufferWidth = Width;
D3DPresentParam.BackBufferHeight = Height;
D3DPresentParam.BackBufferFormat = D3DFMT_A8R8G8B8;
D3DPresentParam.BackBufferCount = BackCount;
D3DPresentParam.MultiSampleType = D3DMULTISAMPLE_NONE
D3DPresentParam.MultiSampleQuality = 0;
D3DPresentParam.SwapEffect = D3DSWAPEFFECT_DISCARD;
D3DPresentParam.hDeviceWindow = hWnd;
D3DPresentParam.Windowed = TRUE;
D3DPresentParam.EnableAutoDepthStencil = FALSE;
D3DPresentParam.AutoDepthStencilFormat = D3DFMT_D24S8;
D3DPresentParam.Flags = 0;
D3DPresentParam.FullScreen_RefreshRateInHz = 0;
D3DPresentParam.PresentationInterval = D3DPRESENT_INTERVAL_IMMEDIATE;

lpD3D->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd, D3DCREATE_HARDWARE_VERTEXPROCESSING | D3DCREATE_MULTITHREADED, &D3DPresentParam, &lpD3DDev);

lpD3DDev->GetSwapChain(0, &lpSwapChain[0]);
D3DPresentParam.PresentationInterval = D3DPRESENT_INTERVAL_DEFAULT;
lpD3DDev->CreateAdditionalSwapChain(&D3DPresentParam, &lpSwapChain[1]);

lpSwapChain[1]->GetBackBuffer(0, D3DBACKBUFFER_TYPE_MONO, &lpBackBuffer);
lpD3DDev->SetRenderTarget(0, lpBackBuffer);
lpBackBuffer->Release();

lpD3DDev->BeginScene();
ここで色々描画
lpD3DDev->EndScene();
lpD3DDev->Present(NULL, NULL, NULL, NULL);