[CryoTheRenegade]

Follow-up to #3580, #3605, #3617, #3628 and #3630. The shadow volume code swaps two silhouette edges by reading and writing their Short indices through an Int pointer. Accessing a Short array through an Int is undefined behavior, the same problem as #3521.

Summary

silhouetteIndices stores each edge as a start and end index. constructVolume and constructVolumeVB in both games move the edge that connects to the current one next to it. They now swap the start and end with std::swap:

 				//swap the two edges
-				Int tempIndex=*(Int *)(&silhouetteIndices[i+2]);
-				*(Int *)&silhouetteIndices[i+2]=*(Int *)&silhouetteIndices[k];
-				*(Int *)&silhouetteIndices[k]=tempIndex;
+				std::swap(silhouetteIndices[i+2], silhouetteIndices[k]);
+				std::swap(silhouetteIndices[i+3], silhouetteIndices[k+1]);

i and k both step by 2, so i+2 and k are always the start of an edge. When k is i+2, both versions leave the edge as it is.

Evidence

• Disassembly: I compared both games' W3DVolumetricShadow objects against a build of main.
  • VS 2026 (ClangCL) Release: only constructVolume and constructVolumeVB changed. Each swap now uses four 16-bit loads and stores instead of two 32-bit ones. The other differences are register choice and block order. The float instructions and calls are the same.
  • VC6 Release: the same two functions changed, in the same way, plus stack slot and alignment padding changes. The rest of the object differs only in renumbered labels.

AI Disclosure

Claude Opus 5.5 was used to aid in implementation and to compare the disassembly.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	⚠️ Failed 2026-10-30T00:22:33.701015Z We couldn’t complete this review. Comment @codex review to try again.	19523c9	PR opened

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[coderabbitai]

Walkthrough

Both game variants replace packed integer access with individual index swaps in the silhouette-edge ordering logic of constructVolume and constructVolumeVB. The edge-pair ordering logic and connection-search condition remain unchanged.

Changes

Volumetric shadow index swaps

Layer / File(s)	Summary
Replace packed silhouette-index swaps Generals/.../W3DVolumetricShadow.cpp, GeneralsMD/.../W3DVolumetricShadow.cpp	Both functions in each game variant now swap the two edge indices individually instead of accessing them through a casted Int pointer.

Priority: Low

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Refactor

Possibly related PRs

• TheSuperHackers/GeneralsGameCode#3628: Removes pointer casts in constructVolumeVB in the same shadow-volume implementation.
• TheSuperHackers/GeneralsGameCode#3532: Replaces unsafe float/integer pointer reinterpretation in a related cast-removal change.
• TheSuperHackers/GeneralsGameCode#3605: Removes matrix-row casts in W3DVolumetricShadow and related water code.

Suggested labels: Refactor, Minor, Rendering, Gen, ZH

Suggested reviewers: xezon, skyaero42

Merge Risk: Minimal · up to 19523

This narrowly scoped refactor preserves volumetric-shadow index behavior with no established merge-blocking risk.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main change: replacing the Int cast with std::swap for silhouette edge indices.
Description check		The description directly explains the undefined-behavior fix, the affected functions and games, the swap behavior, and the reported disassembly evidence.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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[greptile-apps]

Confidence Score: 5/5

[Low impact] The PR appears safe to merge; the new swaps preserve the existing edge ordering.

Summary

Replaces four edge swaps through Int pointers with paired std::swap calls in both games.

• Shadow-volume builders swap silhouette-edge endpoints one index at a time.

_{Reviews (1) · Last reviewed commit: "refactor(w3ddevice): Swap the silhouette..." · Reviewed by Greptile}