CNC-DDRAW instant desync for RA2YR

[CnCRAZER]

Some players are experiencing instant desyncs when using this renderer on RA2YR as of client version 9.0.0.

I officially support any and all players to no longer use this until a fix is resolved.

This causes a desync for all players during an online game even if other players are using different renders or their own systems aren't affected from some unknown reason.

As they are desyncs the logs and crashes are very difficult to determine.

This should be diagnosed and remedied

[FunkyFr3sh]

Does that only happen with the latest cnc-ddraw build? Experimental?

[Starkku]

Confirmed to happen on 7.1.0.0, appears to be some kind of interference with game's CRT functions (or at least sscanf) using floats or at least that is what it was isolated to by testing.

[FunkyFr3sh]

Could you test older versions as well? If we can find out which version introduced the bug then it may easy to fix - otherwise it would take some time to get it fixed (limited time/motivation atm) Starkku ***@***.***> schrieb am So., 23. Nov. 2025, 00:40:

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*Starkku* left a comment (FunkyFr3sh/cnc-ddraw#453) <#453 (comment)> Confirmed to happen on 7.1.0.0, appears to be some kind of interference with game's CRT functions (or at least sscanf) or at least that is what it was isolated to by testing. — Reply to this email directly, view it on GitHub <#453 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB7X3JLJI2YR4TEDFQTXNFD36DX6PAVCNFSM6AAAAACMJGKFPKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKNRXGE2TCMJRGY> . You are receiving this because you commented.Message ID: ***@***.***>

[universal963]

I'm guessing if it is related to a removed setting "fpupreserve", since this setting seems to have an influence on floating point precision.

[CnCRAZER]

Per testing with the affected player, the direct3d9 and direct3d9on12 cause desyncs. Bisection using direct3d9 shows that the earliest appearance for the issue is in version 6.3.0.0 (the desync happens pretty quickly once the first chrono miner is up, usually before even war factory; we considered around 3-5 harvesters on map without desyncs to be a success)

Experimental release still has same issue
@FunkyFr3sh

[FunkyFr3sh]

Does he use windows 11 and the steam version of the game?

[ZivDero]

Does he use windows 11 and the steam version of the game?

Here are the user's specs:

Processor Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz (2.59 GHz)
Graphics Card NVIDIA GeForce RTX 2080 with Max-Q Design 8GB
Installed RAM 16.0 GB
System type 64-bit operating system, x64-based processor
Windows 11 Home

Since we're redistributing our own gamemd.exe in CnCNet we don't think it matters a lot whether it was from Steam version? The EXE is from old Origin version, @Belonit may correct me if I am wrong.

[FunkyFr3sh]

If I remember right the steam version sets a compatibility mode into the registry, which did break the direct3d renderer. That's why cnc-ddraw would always use direct3d9on12 now in that case.

My guess is that the direct3d9on12 renderer never actually worked for YR multi-player.

Would be easy to test - find someone who does not have the sync issues and let him try a game with direct3d9on12.

[Belonit]

Since we're redistributing our own gamemd.exe in CnCNet we don't think it matters a lot whether it was from Steam version? The EXE is from old Origin version, @Belonit may correct me if I am wrong.

@FunkyFr3sh, We are using vanilla (CD version) gamemd.exe, renamed to gamemd-spawn.exe, so compatibility modes should not apply

[FunkyFr3sh]

Hmm... Can you guys upload some logs?

#44

[MahBoiDeveloper]

If I remember right the steam version sets a compatibility mode into the registry, which did break the direct3d renderer. That's why cnc-ddraw would always use direct3d9on12 now in that case.

My guess is that the direct3d9on12 renderer never actually worked for YR multi-player.

Would be easy to test - find someone who does not have the sync issues and let him try a game with direct3d9on12.

One of our devs with Win11 24H2 and Radeon 780M tried renderer=direct3d9on12 it in a lobby with 6 people and did not desync under same circumstances.

[MahBoiDeveloper]

Hmm... Can you guys upload some logs?

#44

Sure, we'll collect logs a bit later.

[Shero83]

Does he use windows 11 and the steam version of the game?

I’m the player that tested with CNC devs (with the specs in the thread). I do not use steam, I got the game through the EA store app.

[ZivDero]

@FunkyFr3sh
Here are the logs. No .dmp files generated by cnc-ddraw as it wasn't a crash.

logs_notdesyncing_player.zip

logs_desyncing_player.zip

[FunkyFr3sh]

The desync logs got the Win7RTM compat mode enabled, that's exactly the one that steam also sets. It breaks the Direct3D renderer.