[Bug 26617] Need for Speed Shift 2: large black squares appear in cockpit, obscuring much of the screen

[wine-bugs at winehq.org]

https://bugs.winehq.org/show_bug.cgi?id=26617

--- Comment #34 from Paul Gofman <gofmanp at gmail.com> ---
(In reply to mo78 from comment #33)

> Why it can't go upstream?

See https://bugs.winehq.org/show_bug.cgi?id=34266#c6.

The performance impact of a generic patch like this is disastrous, I can
imagine 5-10 times drop in shader performance. It is not an option to consider.
There are less invasive approaches, like avoiding infinity in 1/x, 1/sqrt(x)
functions, but these are:

- not universal, it will help some games suffering from this problem, but won't
help some other;
- can cause bugs in the other games;
- still affect performance.

Unfortunately we can't expect this problem to be solved through d3d9 to Vulkan
translation also, Vulkan math (and Microsoft d3d10+) follow IEEE fp conventions
like opengl.

So for now such patch like this can probably only appear as an app specific
hack in special builds. I am not sure, maybe we can discuss if some hack like
this can be considered for Staging as configurable option, at least to give a
way to diagnose this easily. Yet I am not sure I would want to suggest to add
such a registry key, people will leave it on just in case in recycled Wine
prefixes and then report terrible performance. Don't know, maybe through the
environment variable, so it couldn't be set persistent for Wine prefix.

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