[PATCH v2 0/1] MR5687: ddraw: Set dwMaxVertexCount to 2048.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=44863 The bug has been fixed already by moving ddraw4 vertex buffers into system memory. Changing this value makes the game create a smaller buffer, which makes the game fast on video memory buffers. I think we should stay close to what Windows drivers report even though we mitigated the original issue in a different way. -- v2: ddraw: Set dwMaxVertexCount to 2048. https://gitlab.winehq.org/wine/wine/-/merge_requests/5687
From: Stefan Dösinger <stefan(a)codeweavers.com> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=44863 The bug has been fixed already by moving ddraw4 vertex buffers into system memory. Changing this value makes the game create a smaller buffer, which makes the game fast on video memory buffers. I think we should stay close to what Windows drivers report even though we mitigated the original issue in a different way. --- dlls/ddraw/ddraw.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/dlls/ddraw/ddraw.c b/dlls/ddraw/ddraw.c index 5cea4677439..ed342bfd708 100644 --- a/dlls/ddraw/ddraw.c +++ b/dlls/ddraw/ddraw.c @@ -1231,8 +1231,36 @@ void ddraw_d3dcaps1_from_7(D3DDEVICEDESC *caps1, D3DDEVICEDESC7 *caps7) caps1->dpcTriCaps = caps7->dpcTriCaps; caps1->dwDeviceRenderBitDepth = caps7->dwDeviceRenderBitDepth; caps1->dwDeviceZBufferBitDepth = caps7->dwDeviceZBufferBitDepth; + + /* This value is zero on all Windows drivers we have seen so far. */ caps1->dwMaxBufferSize = 0; - caps1->dwMaxVertexCount = 65536; + + /* AMD GPUs on Windows XP and newer report 1024 for HAL devices. + * Nvidia GPUs report 65534. On Windows 9x we have seen 2048 on + * AMD cards and 32768 on Nvidia. The API defined limit is 65536 + * because ddraw only supports 16 bit indices. + * + * Some games, for example Prince of Persia 3D (bug 44863), create a + * vertex buffer to hold as many vertices as we report here. The + * game requests a video memory buffer, maps it, writes a handful + * of vertices and draws. Because IDirect3DVertexBuffer::Lock does + * not allow passing a range, and prior to d3d7 doesn't support + * NOOVERWRITE/DISCARD, the upload becomes slow if the buffer is too + * large. So we don't want to report a value that's too high here. + * + * Why 2048? Windows 9x was the contemporaneous system when d3d 1-4 + * titles were written. + * + * Regardless of this value, we put ddraw4 vertex buffers into + * system memory because games are using them poorly. This mitigates + * negative effects of a large vertex count. + * + * Windows doesn't enforce this limit. A larger vertex buffer can + * be created and used in draws. More vertices than dwMaxVertexCount + * can be rendered in one draw call. SetExecuteData with a vertex + * count exceeding dwMaxVertexCount succeeds too. */ + caps1->dwMaxVertexCount = 2048; + caps1->dwMinTextureWidth = caps7->dwMinTextureWidth; caps1->dwMinTextureHeight = caps7->dwMinTextureHeight; caps1->dwMaxTextureWidth = caps7->dwMaxTextureWidth; -- GitLab https://gitlab.winehq.org/wine/wine/-/merge_requests/5687
I've pushed an updated patch that sets dwMaxVertexCount=2048 but drops the tests (because Windows turns out to be all over the place). I've done some more ad-hoc testing with dwVertexCount in SetExecuteData and found that Windows doesn't enforce the limit (neither do we). -- https://gitlab.winehq.org/wine/wine/-/merge_requests/5687#note_74566
This merge request was approved by Elizabeth Figura. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/5687
participants (2)
-
Elizabeth Figura (＠zfigura) -
Stefan Dösinger