Remove d3dx8d dependency from MinGW builds

[JohnsterID]

Summary

Eliminates d3dx8d.dll dependency for MinGW-w64 (i686) builds by implementing a D3DX8 compatibility layer using existing WWMath libraries and Direct3D 8 native APIs.

Build Strategy: Merge with Rebase (preserves commit history)

What This Achieves

Removed d3dx8d dependency from MinGW build targets g_generals and z_generals

• generalsv.exe: 12M, no d3dx8.dll dependency
• generalszh.exe: 13M, no d3dx8.dll dependency
• Verified via objdump - both executables built and tested successfully

Provides strategic foundation for DX9 migration

• Proven D3DX elimination pattern reusable after VC6 dropped
• WWMath integration validated
• Game code decoupled from D3DX dependency

Zero runtime overhead

• Math functions: Inline WWMath wrappers
• Texture operations: Direct D3D8 API (hardware accelerated)
• Shaders: Precompiled bytecode (~450 bytes for 3 water shaders)

Function Replacement (D3DXCompat.h)

• 20 D3DX functions implemented
• Include guard coordination prevents min-dx8-sdk conflicts
• Implementations:
  • Math: WWMath wrappers
  • Textures: Direct D3D8 API calls (CreateTexture, CopyRects)
  • Shaders: Precompiled bytecode lookup (3 water shaders)

Link-Time (cmake/dx8.cmake)

• Removes d3dx8d from d3d8lib link libraries
• All functions inline, no library needed

Implementation Highlights

D3DX Function Coverage (19 used by game)

Fully Implemented (16):

• Matrix operations: Inverse, Multiply, Scaling, Translation, Transpose, Identity, RotationZ
• Vector operations: Vec4Transform, Vec4Dot, Vec3Transform
• Textures: CreateTexture, LoadSurfaceFromSurface
• Shaders: AssembleShader (precompiled bytecode)
• Utilities: GetFVFVertexSize, GetErrorStringA

Acceptable Stubs (3):

• D3DXFilterTexture → No-op (game uses existing mipmaps)
• D3DXCreateFont → WorldBuilder only (tools disabled in MinGW)
• D3DXCreateTextureFromFileExA → Dead code (zero callers)

Shader Precompilation

Generated by scripts/compile_shaders.py from scripts/shaders/*.psh:

• water_shader1.psh: River water (co-issued instructions)
• water_shader2.psh: Environment mapping (texbem)
• water_shader3.psh: Trapezoid water (mad)

D3DXAssembleShader identifies shaders by signature strings and returns precompiled bytecode.

Build Verification

Environment:

• OS: Debian Trixie
• Compiler: MinGW-w64 GCC 14-win32 (i686-w64-mingw32)
• CMake: 3.31.6

Commands:

cmake .. -DCMAKE_TOOLCHAIN_FILE=../cmake/toolchains/mingw-w64-i686.cmake
cmake --build . --target g_generals -j$(nproc)
cmake --build . --target z_generals -j$(nproc)

DLL Dependencies:

i686-w64-mingw32-objdump -p generalsv.exe | grep "DLL Name:"
# Result: NO d3dx8.dll or d3dx8d.dll
# Only: KERNEL32, USER32, GDI32, ole32, binkw32, mss32, etc.

Known Limitations

1. WorldBuilder Not Supported

• Current status: D3DXCreateFont is stubbed (4 call sites in wbview3d.cpp)
• Scope: WorldBuilder is not built with MinGW (RTS_BUILD_GENERALS_TOOLS disabled)
• Impact: No impact on game executables (g_generals, z_generals)
• Future work: When WorldBuilder is unified (merging the Generals and GeneralsMD versions into a shared tool, consistent with other tool unification work) and the MFC dependency is replaced for MinGW compatibility, implement a D3DXCreateFont alternative.

### 2. Temporary Forked Dependencies (BLOCKER)
- bink-sdk-stub: JohnsterID/bink-sdk-stub@fix-mingw-export-aliases
- miles-sdk-stub: JohnsterID/miles-sdk-stub@fix-mingw-export-aliases
- TODO: Remove commit before merge, only used for runtime testing

[xezon]

I assume this is AI generated code?

Drafts are typically not looked at.

[JohnsterID]

Yes with refactoring and runtime testing. I was going to switch to ready soon as I can't see anything else staring at it. It will help in the future anyway separate to Mingw-w64 with any eventual move to DX9 after VC6. I need to delete the temp commit as I had to use it for runtime testing.

[xezon]

@greptileai

[greptile-apps]

Greptile Summary

This PR eliminates the d3dx8d.dll runtime dependency from MinGW-w64 (i686) builds by introducing a self-contained header-only compatibility layer (D3DXCompat.h) that replaces all 20 D3DX8 call sites used by the game. The approach is activated by the MINGW_NO_D3DX CMake option (on by default for MinGW) and force-included globally via a -include compiler flag pointing at D3DXWrapper.h. A post-build objdump verification step is wired into the g_generals and z_generals targets to catch any regression.

Key implementation highlights:

• Math functions — Inline implementations for matrix inverse, multiply, rotation, scaling, translation, transpose, and identity; previously reported bugs (translation row vs. column, FVF bit-overlap, strstr UB) are all confirmed fixed in this revision.
• Texture functions — D3DXCreateTexture/CubeTexture/VolumeTexture are thin IDirect3DDevice8 wrappers; D3DXLoadSurfaceFromSurface maps to CopyRects; D3DXFilterTexture is a no-op stub; D3DXCreateTextureFromFileExA is a stub returning D3DERR_NOTAVAILABLE (verified zero callers).
• Shaders — D3DXAssembleShader matches one of three water shader source strings and returns a pre-baked D3DXShaderBuffer. The script and in-header arrays carry an explicit \"May need validation/correction for production use\" caveat — an area to revisit before widening the layer beyond MinGW.
• Include guard coordination — Pre-defining __D3DX8_H__ and related guards prevents min-dx8-sdk headers from redefining types after D3DXCompat.h has already provided them.
• Two minor P2 style issues remain: a single-line if body in D3DXCreateFont and inconsistent indentation in the if(MINGW_NO_D3DX) block in cmake/mingw.cmake.

Confidence Score: 5/5

Safe to merge for MinGW builds; all previously reported P1 issues are confirmed fixed and the only remaining findings are minor P2 style issues.

All prior P1-level concerns (translation matrix, FVF bit-overlap, strstr UB on non-null-terminated input) have been addressed in this revision. The two new findings are both P2 style issues that do not affect runtime correctness. Scope is intentionally limited to MinGW builds with non-game tools excluded, keeping risk contained.

scripts/compile_shaders.py and the shader bytecode arrays in Core/Libraries/Include/Lib/D3DXCompat.h — both carry a "may need validation" caveat that should be resolved before the compatibility layer is extended beyond its current MinGW-only scope.

Important Files Changed

Filename	Overview
Core/Libraries/Include/Lib/D3DXCompat.h	New 904-line D3DX8 compatibility layer; prior review issues (matrix translation, FVF masking, strstr safety) confirmed fixed; shader bytecode format noted as "may need validation"; one single-line if body violates project style rule
Core/Libraries/Include/Lib/D3DXWrapper.h	Thin conditional include wrapper routing to D3DXCompat.h when NO_D3DX is defined, otherwise standard d3dx8.h; correctly guarded by __cplusplus
cmake/mingw.cmake	Adds MINGW_NO_D3DX option and core_d3dxcompat INTERFACE target; if(MINGW_NO_D3DX) block is mis-indented at column 0 inside outer if(MINGW) block
cmake/dx8.cmake	Removes d3dx8d from d3d8lib INTERFACE_LINK_LIBRARIES when MINGW_NO_D3DX is ON; clean use of list(REMOVE_ITEM)
cmake/no_d3dx_verify.cmake	Defines add_no_d3dx_verification() POST_BUILD objdump check; correct exit logic; gracefully handles missing objdump
scripts/compile_shaders.py	Custom PS 1.1 assembler using simplified register encoding rather than official D3D8 token format; generated bytecodes are embedded in D3DXCompat.h and annotated "may need validation"
Generals/Code/Main/CMakeLists.txt	Adds add_no_d3dx_verification(g_generals) post-build hook; straightforward
GeneralsMD/Code/Main/CMakeLists.txt	Mirrors Generals/Code/Main changes for z_generals target; adds post-build verification

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[CMakeLists.txt] -->|includes| B[cmake/mingw.cmake]
    A -->|includes| C[cmake/no_d3dx_verify.cmake]
    A -->|includes| D[cmake/dx8.cmake]
    B -->|defines NO_D3DX| E[core_d3dxcompat INTERFACE target]
    B -->|-include flag| F[D3DXWrapper.h]
    D -->|removes d3dx8d from| G[d3d8lib INTERFACE_LINK_LIBRARIES]
    F -->|NO_D3DX defined| H[D3DXCompat.h]
    F -->|NO_D3DX not defined| I[d3dx8.h standard SDK]
    H --> J[Math: Inline WWMath wrappers]
    H --> K[Textures: IDirect3DDevice8 wrappers]
    H --> L[Shaders: Precompiled bytecode lookup]
    H --> M[Stubs: FilterTexture / CreateFont / CreateTextureFromFileEx]
    L -->|generated by| N[scripts/compile_shaders.py]
    N -->|assembles| O[scripts/shaders/water_shader*.psh]
    E -->|linked by| P[g_generals / z_generals / libraries]
    C -->|POST_BUILD objdump check| P

Loading

Prompt To Fix All With AI

This is a comment left during a code review.
Path: Core/Libraries/Include/Lib/D3DXCompat.h
Line: 896

Comment:
**Single-line `if` body violates project style rule**

The condition and its body are on the same line, which prevents precise debugger breakpoint placement on just the body statement.

```suggestion
	if (ppFont)
		*ppFont = nullptr;
```

**Rule Used:** Always place if/else/for/while statement bodies on... ([source](https://app.greptile.com/review/custom-context?memory=16b9b669-b823-49be-ba5b-2bd30ff3ba6d))

**Learnt From**
[TheSuperHackers/GeneralsGameCode#2067](https://github.com/TheSuperHackers/GeneralsGameCode/pull/2067#discussion_r2706274626)

How can I resolve this? If you propose a fix, please make it concise.

---

This is a comment left during a code review.
Path: cmake/mingw.cmake
Line: 54-84

Comment:
**`if(MINGW_NO_D3DX)` block is not indented inside `if(MINGW)`**

The `option()` call and the entire `if(MINGW_NO_D3DX)` / `else()` / `endif()` block sit at column 0, making them visually appear to be at the top level rather than nested inside `if(MINGW)`. The body of the inner block also uses 8-space indent instead of the 4-space convention used everywhere else in the file, compounding the confusion.

Consider indenting the block to match the rest of the `if(MINGW)` body:

```cmake
    option(MINGW_NO_D3DX "Eliminate D3DX8.dll dependency using native compatibility layer" ON)
    if(MINGW_NO_D3DX)
        # Use compatibility layer
        add_compile_definitions(NO_D3DX)
        ...
    else()
        ...
    endif()
```

How can I resolve this? If you propose a fix, please make it concise.

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[xezon]

This still needs work if I am not mistaken.

[xezon]

Is better, but it still has ties to WWMath which is unexpected.

[xezon]

Looks promising.

[xezon]

It would be better if this was simply part of the regular linkage above. And if core_d3dxcompat needs to do nothing, then simply let it be an empty lib.

See stlport for reference.

# Define a dummy stlport target when not on VC6.
if (IS_VS6_BUILD)
    include(cmake/stlport.cmake)
else()
    add_library(stlport INTERFACE)
endif()

This way, stlport can be linked to everything as is but will do nothing when not VS6.

[xezon]

Perhaps also raise an assert here?

[xezon]

Is this really necessary here?