[PATCH 1/5] d3d9: Support drawing from D3DPOOL_SYSTEMMEM vertex buffers.

[Józef Kucia]

On Wed, Dec 12, 2018 at 5:10 PM Matteo Bruni <mbruni at codeweavers.com> wrote:
> +static void d3d9_device_upload_sysmem_buffers(struct d3d9_device *device,
> +        unsigned int start_vertex, unsigned int vertex_count)
> +{
> +    struct wined3d_box box = {0, 0, 0, 1, 0, 1};
> +    struct d3d9_vertexbuffer *d3d9_buffer;
> +    unsigned int i, offset, stride, map;
> +    struct wined3d_buffer *dst_buffer;
> +    HRESULT hr;
> +
> +    map = device->upload_map;
> +    while (map)
> +    {
> +        i = ffs(map) - 1;
> +        map ^= 1u << i;
> +
> +        if (FAILED(hr = wined3d_device_get_stream_source(device->wined3d_device, i, &dst_buffer, &offset, &stride)))
> +            ERR("Failed to get stream source.\n");
> +        d3d9_buffer = wined3d_buffer_get_parent(dst_buffer);
> +        box.left = offset + start_vertex * stride;
> +        box.right = box.left + vertex_count * stride;
> +        if (FAILED(hr = wined3d_device_copy_sub_resource_region(device->wined3d_device,
> +                wined3d_buffer_get_resource(dst_buffer), 0, box.left, 0, 0,
> +                wined3d_buffer_get_resource(d3d9_buffer->wined3d_buffer), 0, &box, 0)))
> +            ERR("Failed to update buffer.\n");
> +    }
> +}

It looks like this might stall the rendering pipeline frequently, i.e.
we will be updating the same draw buffers continuously between
subsequent draw calls with system memory buffers. I am not sure how
important it is in practice.