From: Henri Verbeet <hverbeet@gmail.com>
Subject: Re: [PATCH] ddraw: Allow GPU access to D3DVBCAPS_SYSTEMMEMORY vertex buffers.
Message-Id: <CAOsNvwxDR=Pq4sArO=GwMQ+gWEyWSLwkfG-QpuCJu9BCPHLEJQ@mail.gmail.com>
Date: Mon, 15 Oct 2018 19:11:51 +0330
In-Reply-To: <20181015150245.18903-1-mbruni@codeweavers.com>
References: <20181015150245.18903-1-mbruni@codeweavers.com>

On Mon, 15 Oct 2018 at 18:33, Matteo Bruni <mbruni@codeweavers.com> wrote:
> The original Deus Ex uses a D3DVBCAPS_SYSTEMMEMORY buffer with
> DrawPrimitiveVB() and expects it to work.
>
> It should also help with bug 45279 and 45486.
>
> The device is probably created with
> D3DCREATE_SOFTWARE_VERTEXPROCESSING, which would explain why this is
> accepted on Windows. With core profile we need to create a VBO anyway
> so I think this is the correct fix in practice.
>
> This is an alternative to
> https://source.winehq.org/patches/data/152581, main difference is
> fixing the issue in ddraw instead of wined3d.
>
This is probably fine, but note that one other alternative would be to
implement DrawPrimitiveVB() calls with SYSTEMMEMORY buffers on top of
regular DrawPrimitive(). The main advantage of that would be that we'd
only impose a penalty on applications that actually do draws like
that, and we'd avoid issues with applications doing small draws from
large/huge SYSTEMMEMORY buffers.