问texture2d资源在directx11中的读取

EN

//(all HRESULT checked already)
    int WIDTH = 10, HEIGHT = 2;

    ID3D11Texture2D* resource; // create texture------------------------------
    D3D11_TEXTURE2D_DESC texDesc;
    texDesc.BindFlags = D3D11_BIND_SHADER_RESOURCE;
    texDesc.Usage = D3D11_USAGE_IMMUTABLE;
    texDesc.Format = DXGI_FORMAT_R32G32B32A32_FLOAT;
    texDesc.Width = WIDTH;
    texDesc.Height = HEIGHT;
    texDesc.CPUAccessFlags = 0;
    texDesc.ArraySize = 1;
    texDesc.MipLevels = 1;
    texDesc.SampleDesc.Count = 1;
    texDesc.SampleDesc.Quality = 0;
    texDesc.MiscFlags = 0;

    XMFLOAT4* initValues = new XMFLOAT4[WIDTH * HEIGHT];
    for (int i = 0; i < WIDTH * HEIGHT; ++i) {
        initValues[i] = XMFLOAT4(1,1,1,1);
    }
    D3D11_SUBRESOURCE_DATA data;
    data.pSysMem = initValues;
    data.SysMemPitch = sizeof(XMFLOAT4)*WIDTH;
    data.SysMemSlicePitch = 0;
    device->CreateTexture2D(
        &texDesc,
        &data,
        &resource);

    ID3D11Texture2D* staging; // create texture for reading --------------------
    D3D11_TEXTURE2D_DESC stgDesc;
    stgDesc.BindFlags = 0;
    stgDesc.Usage = D3D11_USAGE_STAGING;
    stgDesc.Format = DXGI_FORMAT_R32G32B32A32_FLOAT;
    stgDesc.Width = WIDTH;
    stgDesc.Height = HEIGHT;
    stgDesc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
    stgDesc.ArraySize = 1;
    stgDesc.MipLevels = 1;
    stgDesc.SampleDesc.Count = 1;
    stgDesc.SampleDesc.Quality = 0;
    stgDesc.MiscFlags = 0;
    device->CreateTexture2D(
        &stgDesc,
        nullptr,
        &staging);

    XMFLOAT4* outputArr = new XMFLOAT4[WIDTH*HEIGHT]; // READ-------------------
    dContext->CopyResource(staging, resource);
    D3D11_MAPPED_SUBRESOURCE mappedResource;
    ZeroMemory(&mappedResource, sizeof(D3D11_MAPPED_SUBRESOURCE));
    dContext->Map(staging, 0, D3D11_MAP_READ, 0, &mappedResource);

    outputArr = reinterpret_cast<XMFLOAT4*>(mappedResource.pData);
    std::vector<XMFLOAT4> testV;
    for (int y = 0; y < HEIGHT; ++y)
    {
        for (int x = 0; x < WIDTH; ++x)
        {
            int idx = y * WIDTH + x;

            testV.push_back(outputArr[idx]);
        }
    }

    dContext->Unmap(staging, 0);