feat(math): Route game logic math through WWMath with 3-mode deterministic support

[Okladnoj]

Rework of #2602, incorporating review feedback:

• GameMath via FetchContent (per @stephanmeesters, @OmniBlade recommendation)
• Trig.cpp preserved, redirected to WWMath instead of deleted (per @xezon request for standalone change)
• 3 math modes: VC6 (x87 inline asm), CRT (standard library), GameMath deterministic (per @Mauller recommendation)
• USE_DETERMINISTIC_MATH unconditional for non-VC6 — missing gmath.h is now a compile error instead of silent fallback to x87/CRT
• Clean history from main

CI: win32 + vc6 ✅, replay checks ✅

Open question: Replay checks pass both with and without USE_DETERMINISTIC_MATH, even though golden replays were recorded with an x87 build. The replays may not contain MSG_LOGIC_CRC messages, meaning the check only validates absence of crashes rather than game state CRC parity. If anyone has insight on this — please share.

Testing results

Cross-platform deterministic math parity verified with SimulationMathCrc::runBenchmark — computes CRC over 10 000 iterations of sin/cos/tan/atan2/sqrt/pow across a fixed input set.

System	Compiler	Math Library	CRC	Perf (10 000 iters)
Win32 x86	MSVC (modern)	fdlibm (deterministic)	🟩 76B53840	~6 ms
macOS ARM64	Apple Clang	fdlibm (deterministic)	🟩 76B53840	~11 ms
Win32 x86	MSVC (modern)	system math (native)	🟦 E8B6385A	~3 ms
macOS ARM64	Apple Clang	system math (native)	🟦 E8B6385A	~5 ms
Win32 x86	VC6 (legacy)	x87 CRT (no fdlibm)	🟧 B7B83850	~17 ms
Win32 x86	VC6 (legacy)	system math (native)	🟥 8BB5B841	~5 ms

• 🟩 cross-platform deterministic parity achieved (Win32 modern = macOS ARM64)
• 🟦 native system math match (Win32 modern = macOS ARM64)
• 🟧 VC6 deterministic (x87 CRT, separate group — fdlibm not supported)
• 🟥 VC6 native (x87 CRT, separate group)

Key fix: -ffp-contract=off in cmake/compilers.cmake — prevents Clang from emitting FMA instructions (fmadd) that skip intermediate rounding, breaking bit-exact parity with MSVC's /fp:precise default.

[greptile-apps]

Greptile Summary

Routes all game-logic floating-point math through a new WWMath abstraction layer that selects between three modes at compile time: fdlibm deterministic (non-VC6), CRT native (non-VC6 fallback when gmath.h is absent), and x87 inline-asm (VC6 legacy). GameMath is fetched via CMake FetchContent and pinned to a specific commit; -ffp-contract=off is added for Clang to prevent FMA contraction that would break cross-platform CRC parity with MSVC /fp:precise.

• wwmath.h gains two inline wrapper families: *_Trig (replacing bare CRT calls from Trig.cpp) and *_Origin (replacing standalone sqrt/fabs/atan2 etc. across ~40 game-logic files); USE_DETERMINISTIC_MATH is set via __has_include(\"gmath.h\") so targets without the include path fall back silently.
• cmake/gamemath.cmake declares the FetchContent dependency, forces GM_ENABLE_INTRINSICS=OFF for bit-exact cross-arch parity, and uses include_directories globally so the __has_include guard fires consistently.
• SimulationMathCrc is split into a deterministic and a native CRC path, with a new runBenchmark diagnostic (defaulted off via RUN_MATH_BENCHMARK_REPLAY400_FLAG=0) used to produce the CRC table in the PR description.

Confidence Score: 5/5

Safe to merge; the routing changes are mechanical substitutions with no altered semantics, verified by cross-platform CRC benchmarks in the PR description.

The diff is a large but uniform mechanical rerouting of math calls through well-tested wrapper functions. The -ffp-contract=off flag and pinned GameMath commit address the key cross-platform reproducibility risk. All call sites pass float-width values so the documented double-to-float narrowing in the _Origin double overloads is lossless. CI passes for both win32 and VC6 paths.

No files require special attention; wwmath.h is the most complex changed file but its structure is straightforward conditional compilation.

Important Files Changed

Filename	Overview
Core/Libraries/Source/WWVegas/WWMath/wwmath.h	Core of the PR: adds conditional gmath.h include via __has_include, USE_DETERMINISTIC_MATH macro, and two new families of inline wrappers (*_Trig and *_Origin) routing all trig/math calls to fdlibm in deterministic mode or CRT otherwise.
cmake/gamemath.cmake	New FetchContent declaration for the GameMath fdlibm fork; pins to a specific commit SHA, disables intrinsics (FORCE) for cross-arch determinism, and uses global include_directories so __has_include fires consistently.
cmake/compilers.cmake	Adds -ffp-contract=off for non-MSVC compilers to prevent FMA contraction that would break bit-exact CRC parity between MSVC /fp:precise and Clang.
Core/GameEngine/Source/Common/Diagnostic/SimulationMathCrc.cpp	Splits into two distinct CRC functions (deterministic vs native) and adds a runBenchmark utility gated behind RUN_MATH_BENCHMARK_REPLAY400_FLAG=0. Two if (i == 0) guards have statement bodies on the same line as the condition.
Core/Libraries/Include/Lib/BaseType.h	Routes sqrt calls in Coord2D, ICoord2D, Coord3D, ICoord3D helper methods to the new Sqrt() free function from trig.h, which delegates to WWMath::Sqrt_Origin.
Core/Libraries/Include/Lib/trig.h	Adds double Sqrt(double x) declaration alongside the existing trig function declarations; implementation lives in Trig.cpp.
Core/GameEngine/Source/GameLogic/AI/AIPathfind.cpp	Mechanical substitution of raw sqrt/fabs calls with WWMath::Sqrt_Origin/FAbs_Origin throughout pathfinding cost calculations.
Core/Libraries/Source/WWVegas/WWMath/CMakeLists.txt	Links core_wwmath against the gamemath FetchContent target (PUBLIC, non-VC6 only), propagating deterministic math headers to all consumers.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Game Logic call site] --> B{WWMath wrapper e.g. Sqrt_Origin / Sin_Trig}
    B --> C{USE_DETERMINISTIC_MATH defined?}
    C -- Yes non-VC6 + gmath.h found --> D[fdlibm / GameMath gm_sqrtf / gm_sinf CRC: 76B53840]
    C -- No non-VC6 gmath.h absent --> E[CRT system math sqrtf / sinf CRC: E8B6385A]
    C -- VC6 build IS_VS6_BUILD --> F[x87 inline asm or CRT CRC: B7B83850]
    D --> G[float result]
    E --> G
    F --> G
    G --> H[Game State / CRC]

Loading

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
Core/GameEngine/Source/Common/Diagnostic/SimulationMathCrc.cpp:121-138
Both `if (i == 0)` checks place the statement body on the same line as the condition, violating the project's style rule requiring bodies on a separate line for precise debugger breakpoint placement.

```suggestion
        if (i == 0)
            crcDet = xfer.getCRC();
    }
    _fpreset();
    clock_t endDet = clock();
    double timeDetMs = (double)(endDet - startDet) / CLOCKS_PER_SEC * 1000.0;

    clock_t startNat = clock();
    UnsignedInt crcNat = 0;
    
    setFPMode();

    for (i = 0; i < iterations; ++i)
    {
        XferCRC xfer;
        xfer.open("SimMathNat");
        appendSimulationMathCrc_Native(xfer);
        xfer.close();
        if (i == 0)
            crcNat = xfer.getCRC();
```

_{Reviews (7): Last reviewed commit: "refactor(math): Address xezon review fee..." | Re-trigger Greptile}

[Okladnoj]

Here is what replay playback looks like at the moment.

I’m testing this on a separate branch:
https://github.com/Okladnoj/GeneralsGameCode/okji/test/deterministic-math-v2

I slightly adjusted the CI there so I can run Win32 and get access to the game resources.

[Skyaero42]

You did not review the changes you made with AI. It has issues that you should fix before asking it to be reviewed.

[Okladnoj]

reviwed all changes

[xezon]

This change does too many things. It is better to first consolidate trig and wwmath and maybe other sources of math, before going into gamemath territory.

[Okladnoj]

This change does too many things. It is better to first consolidate trig and wwmath and maybe other sources of math, before going into gamemath territory.

@xezon Hey! I understand your point, but the reason I didn't fully consolidate trig and wwmath in this PR is exactly to avoid doing too many things at once.

As we saw in PR #2602, fully removing trig.h and replacing it with WWMath across the codebase touches over 120 files. Mixing a massive 120+ file architectural refactoring with a core feature addition (GameMath) made the previous PR extremely difficult to review and broke compilation for some standalone utilities, because trig.h is used outside of just game math.

That's exactly why I chose this "routing" approach for this PR. By keeping the trig.h interface intact and just routing its internal implementation to WWMath, we achieve the deterministic math goals with a much smaller and safer footprint.

Perhaps the best option would be to test this PR first, and if everything is fine — merge it. And only after that, we can focus on a second PR dedicated purely to the architectural cleanup (removing trig.h across all 120+ files)?