Не могу разобраться с буферизацией в WinApi

LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_PAINT:
    {   
        hdc = BeginPaint(hwnd, &ps);
        memDC = CreateCompatibleDC(hdc);
        memBM = CreateCompatibleBitmap(hdc, clientRect.right - clientRect.left, clientRect.bottom - clientRect.top);
        SelectObject(memDC, memBM);
 
                //что-то рисуется ....
 
        BitBlt(hdc, 0, 0, 1500, 900, memDC, 0, 0, SRCCOPY);
        DeleteObject(memBM);
        DeleteDC(memDC);
        EndPaint(hwnd, &ps);
    }
    return 0;
 
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
 
 
int WINAPI wWinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE , _In_ PWSTR czCmdLine, _In_ int nCmdShow)
{
    HWND hwnd{};
    MSG msg{};
 
    WNDCLASSEX wc{ sizeof(WNDCLASSEX) };
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hbrBackground = reinterpret_cast<HBRUSH>(GetStockObject(DKGRAY_BRUSH));
    wc.hCursor = LoadCursor(nullptr, IDI_APPLICATION);
    wc.hIcon = LoadIcon(nullptr, IDI_APPLICATION);
    wc.hIconSm = LoadIcon(nullptr, IDI_APPLICATION);
    wc.hInstance = hInstance;
    wc.lpfnWndProc = WndProc;
    wc.lpszClassName = L"MyAppClass ";
    wc.lpszMenuName = nullptr;
    wc.style = CS_VREDRAW | CS_HREDRAW;
 
    if (!RegisterClassEx(&wc))
    {
        return EXIT_FAILURE;
    }
 
    hwnd = CreateWindow(wc.lpszClassName, L"Player", WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0, 0, 1500, 900, nullptr, nullptr, nullptr, nullptr);
    if (hwnd == INVALID_HANDLE_VALUE)
    {
        return EXIT_FAILURE;
    }
while (GetMessage(&msg, nullptr, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return static_cast<int>(msg.wParam);
}