refactor(math): Implement Matrix4x4::Inverse, Matrix3D::Get_Inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose #2052

xezon · 2026-01-03T13:51:00Z

Fixes Properly implement transpose between Matrix4 and D3DMatrix #552
Closes refactor(dx8): Replace unsafe Matrix4x4/D3DMATRIX casts with proper transpose conversion #1852

This change implements Matrix4x4::Inverse and Matrix3D::Get_inverse so that we do not need to use D3DXMatrixInverse for Matrix4x4 and Matrix3D anymore (there are 4 callers, verified to produce same result). Chat GPT was used to help implement the text book math.

Eliminates all unsafe C casts (that I was able to find) between D3DMATRIX, D3DXMATRIX and Matrix4x4, Matrix3D.

The following new helpers functions help converting between the matrices:

void To_D3DMATRIX(_D3DMATRIX& dxm, const Matrix3D& m);
_D3DMATRIX To_D3DMATRIX(const Matrix3D& m);
D3DXMATRIX To_D3DXMATRIX(const Matrix3D& m);

void To_D3DMATRIX(_D3DMATRIX& dxm, const Matrix4x4& m);
_D3DMATRIX To_D3DMATRIX(const Matrix4x4& m);
D3DXMATRIX To_D3DXMATRIX(const Matrix4x4& m);

void To_Matrix4x4(Matrix4x4& m, const _D3DMATRIX& dxm);
Matrix4x4 To_Matrix4x4(const _D3DMATRIX& dxm);

TODO

Replicate in Generals

…inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose

xezon · 2026-01-03T13:53:49Z

Generals will fail to compile until replicated.

Core/Libraries/Source/WWVegas/WWMath/matrix3d.cpp

xezon · 2026-01-12T17:39:27Z

@greptileai

greptile-apps · 2026-01-12T17:43:11Z

Greptile Overview

Greptile Summary

Implemented custom matrix inversion for Matrix4x4 and Matrix3D using the adjugate/determinant method, eliminating dependency on D3DXMatrixInverse for these types. Added conversion functions (To_D3DMATRIX, To_D3DXMATRIX, To_Matrix4x4) that properly handle the transpose required when converting between column-major engine matrices and row-major Direct3D matrices.

Key Changes

Matrix Inversion: Implemented Matrix4x4::Inverse and Matrix3D::Get_Inverse using cofactor expansion with comprehensive comments explaining the mathematical approach
Conversion Functions: Added helper functions that apply the required transpose when converting between matrix formats, eliminating all unsafe C-style casts
DX8Wrapper Refactoring: Changed internal storage from Matrix4x4 to D3DMATRIX to avoid redundant conversions and simplified the transform API
Cast Elimination: Removed all dangerous casts like (D3DMATRIX*)&matrix4x4 throughout the codebase, replacing them with proper conversion function calls
Const-correctness: Improved const-correctness in Matrix3x3::Multiply and Matrix3D::Multiply

Notes

The implementation correctly handles the fundamental difference between the engine's column-major, column-vector convention and Direct3D's row-major convention by applying transpose operations during conversion.

Confidence Score: 5/5

This PR is safe to merge with high confidence
The matrix inversion implementation uses standard textbook algorithms (adjugate/determinant method), conversion functions properly handle row-major vs column-major differences with transpose, all unsafe casts have been systematically eliminated, and the PR author verified the results match D3DXMatrixInverse for all 4 callers
No files require special attention

Important Files Changed

File Analysis

Filename	Score	Overview
Core/Libraries/Source/WWVegas/WWMath/matrix4.h	5/5	Implemented `Matrix4x4::Inverse` using adjugate/determinant method and added conversion function declarations for D3DMATRIX interop
Core/Libraries/Source/WWVegas/WWMath/matrix4.cpp	5/5	Implemented matrix inversion and conversion functions (`To_D3DMATRIX`, `To_Matrix4x4`) with proper transpose handling
Core/Libraries/Source/WWVegas/WWMath/matrix3d.h	5/5	Added `Matrix3D::Get_Inverse` static method declaration and conversion function declarations for D3DMATRIX interop
Core/Libraries/Source/WWVegas/WWMath/matrix3d.cpp	5/5	Implemented `Matrix3D::Get_Inverse` using adjugate method, replaced D3DXMatrixInverse call, added conversion functions, removed unsafe cast
GeneralsMD/Code/Libraries/Source/WWVegas/WW3D2/dx8wrapper.h	5/5	Changed internal storage from `Matrix4x4` to `D3DMATRIX`, simplified `_Set_DX8_Transform` to take D3DMATRIX directly
GeneralsMD/Code/Libraries/Source/WWVegas/WW3D2/dx8wrapper.cpp	5/5	Updated transform handling to use conversion functions, removed all unsafe casts, simplified matrix operations
Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DShaderManager.cpp	5/5	Replaced all `Matrix4x4` to `D3DXMATRIX` casts with proper types, removed unsafe pointer casts throughout shader code

Sequence Diagram

sequenceDiagram
    participant App as Application Code
    participant M4 as Matrix4x4/Matrix3D
    participant Conv as Conversion Functions
    participant DX8 as DX8Wrapper
    participant D3D as Direct3D API

    Note over M4: Column-major storage<br/>Row[col][row]
    Note over D3D: Row-major storage<br/>m[row][col]

    App->>M4: Create/manipulate matrix
    M4->>M4: Perform operations (e.g., Inverse)
    
    alt Set Transform
        App->>DX8: Set_Transform(transform, Matrix4x4)
        DX8->>Conv: To_D3DMATRIX(Matrix4x4)
        Note over Conv: Transposes during conversion<br/>dxm.m[i][j] = m[j][i]
        Conv-->>DX8: D3DMATRIX
        DX8->>DX8: Store in render_state
        DX8->>DX8: _Set_DX8_Transform(D3DMATRIX)
        DX8->>D3D: SetTransform(D3DMATRIX*)
    end

    alt Get Transform
        App->>DX8: Get_Transform(transform, Matrix4x4&)
        DX8->>DX8: Retrieve D3DMATRIX from cache
        DX8->>Conv: To_Matrix4x4(D3DMATRIX)
        Note over Conv: Transposes during conversion<br/>m[i][j] = dxm.m[j][i]
        Conv-->>DX8: Matrix4x4
        DX8-->>App: Matrix4x4
    end

    alt Shader Texture Transform
        App->>DX8: _Get_DX8_Transform(D3DTS_VIEW, D3DXMATRIX&)
        DX8->>D3D: GetTransform(D3DXMATRIX*)
        D3D-->>DX8: D3DXMATRIX (row-major)
        DX8-->>App: D3DXMATRIX
        App->>App: D3DXMatrixInverse(&inv, &det, &curView)
        App->>App: Matrix operations in D3DXMATRIX space
        App->>DX8: _Set_DX8_Transform(D3DTS_TEXTURE0, D3DXMATRIX)
        DX8->>D3D: SetTransform(D3DMATRIX*)
    end

greptile-apps

_{3 files reviewed, 3 comments}

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Core/GameEngineDevice/Source/W3DDevice/GameClient/TerrainTex.cpp

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/Shadow/W3DVolumetricShadow.cpp

xezon · 2026-01-12T17:59:13Z

@greptileai

greptile-apps

_{2 files reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

Core/Libraries/Source/WWVegas/WWMath/matrix4.h

Core/Libraries/Source/WWVegas/WWMath/matrix3d.cpp

JohnsterID · 2026-01-12T21:10:23Z

Core/Libraries/Source/WWVegas/WWMath/matrix3d.cpp

 *                                                                                             *
 * HISTORY:                                                                                    *
 *   8/7/98     GTH : Created.                                                                 *
+ *   01/03/2026 TheSuperHackers : Implemented with assistance of Chat GPT.                     *


I don't think the comment is appropriate. ChatGPT is a tool, not an author and attributing tools in code creates legal ambiguity without adding value. GPL already covers licensing and authorship should remain limited to human contributors. Perhaps, to address AI use, it should belong in the project policy not in code comments?

Ok. Tweaked.

refactor(math): Properly implement Matrix4x4::Inverse, Matrix3D::Get_…

e13a37b

…inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose

xezon added this to the Code foundation build up milestone Jan 3, 2026

xezon requested a review from bobtista January 3, 2026 13:51

xezon added Major Severity: Minor < Major < Critical < Blocker Refactor Edits the code with insignificant behavior changes, is never user facing Rendering Is Rendering related labels Jan 3, 2026

xezon mentioned this pull request Jan 3, 2026

refactor(dx8): Replace unsafe Matrix4x4/D3DMATRIX casts with proper transpose conversion #1852

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xezon commented Jan 5, 2026

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Fix Matrix3x3 casts

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xezon added 2 commits January 12, 2026 18:57

Fix syntax

855e2b4

Remove test code

34bceab

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Use MM/DD/YYYY near EA style comments

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refactor(math): Implement Matrix4x4::Inverse, Matrix3D::Get_Inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose #2052

refactor(math): Implement Matrix4x4::Inverse, Matrix3D::Get_Inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose #2052

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xezon commented Jan 3, 2026

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refactor(math): Implement Matrix4x4::Inverse, Matrix3D::Get_Inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose #2052

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refactor(math): Implement Matrix4x4::Inverse, Matrix3D::Get_Inverse and replace unsafe Matrix4x4 to D3DMATRIX casts with conversion functions that apply the required transpose #2052

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xezon commented Jan 3, 2026

TODO

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xezon commented Jan 3, 2026

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xezon commented Jan 12, 2026

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Greptile Overview

Greptile Summary

Key Changes

Notes

Confidence Score: 5/5

Important Files Changed

Sequence Diagram

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