bugfix(render2d): Flush batched 2D draws before they overflow the dynamic buffers by tintinhamans · Pull Request #3487 · TheSuperHackers/GeneralsGameCode

tintinhamans · 2026-10-12T03:05:16Z

Follow up for perf(gui): Significantly reduce cost of 2d render elements #2514

Render2DClass::Render passes Indices.Count() to DynamicIBAccessClass, which takes an unsigned short. 65538 indices become 2, the index buffer is locked for 2, and the copy loop writes all 65538.

Before batching, W3DDisplay called Render after every draw call. With batching, setup2DRenderState previously only flushed when the texture, mode or grayscale changed, so identical draws could accumulate beyond the dynamic buffer limits.

Drawable::drawAmmo hits this: it draws one pip image per round in the clip, and ClipSize is a plain INI::parseInt. A weapon with ShowsAmmoPips and a clip of 10923 produces 65538 indices, and selecting or hovering the unit can write up to 128 KB past the buffer.

DynamicVBAccessClass and DynamicIBAccessClass now define MAX_VERTEX_COUNT and MAX_INDEX_COUNT. Render2DClass::Can_Add checks whether the batch has room for the requested vertices and indices.

Each draw supplies its actual geometry counts to setup2DRenderState, including rotated images and each clock branch. The batch flushes before the next draw would exceed either limit, rather than at half capacity.

Render keeps a runtime guard against an unsafe buffer copy, because WorldBuilder's DrawObject calls it on its own Render2DClass without this flush.

The similar narrowing in drawRiverWater is handled separately.

AI Disclosure: issue identified by Codex Security Cloud and fix implemented with assistance from Opus 5.5

coderabbitai · 2026-10-12T03:05:42Z

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Walkthrough

The Generals and GeneralsMD 2D renderers now check vertex and index capacity. W3DDisplay supplies expected draw counts during batch setup and flushes and reinitializes a batch when it cannot fit the upcoming draw.

Changes

2D renderer capacity checks

Layer / File(s)	Summary
Capacity contract and render guard `Core/Libraries/Source/WWVegas/WW3D2/dx8vertexbuffer.h`, `Generals/Code/Libraries/Source/WWVegas/WW3D2/render2d.`, `GeneralsMD/Code/Libraries/Source/WWVegas/WW3D2/render2d.`	`DynamicVBAccessClass` defines a vertex-count limit. Both `Render2DClass` implementations add `Can_Add` and return without rendering when current geometry exceeds the buffer limits.
Batch capacity check `Core/GameEngineDevice/Include/W3DDevice/GameClient/W3DDisplay.h`, `Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DDisplay.cpp`	`setup2DRenderState` receives expected vertex and index counts. Primitive, clock, image, and video-buffer draw paths provide capacity estimates. The batch is flushed and reinitialized when it cannot fit the upcoming draw.

Priority: Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Possibly related PRs

TheSuperHackers/GeneralsGameCode#3589: Limits and batches river geometry in drawRiverWater.
TheSuperHackers/GeneralsGameCode#3590: Addresses dynamic-buffer limits and geometry culling in river rendering.

Merge Risk: Minimal · up to c588b

No actionable merge-blocking risk remains identified.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main change: flushing batched 2D draws before dynamic-buffer overflow.
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.
Description check		The description directly explains the buffer-overflow risk and the changes that add capacity checks and preemptive batch flushing.

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greptile-apps · 2026-10-12T03:08:24Z

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no actionable defects were found.

Summary

The PR flushes batched 2D draws before either dynamic buffer exceeds its count limit.

2D batches flush before their geometry exceeds buffer limits.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Next 2D draw] --> B{Same draw state and enough room?}
    B -->|Yes| E[Append geometry]
    B -->|No| C[Render and reset current batch]
    C --> D[Set requested draw state]
    D --> E
    E --> F[Flush at batch end or before next incompatible draw]

_{Reviews (7) · Last reviewed commit: "fix(render2d): flush batched draws befor..." · Reviewed by Greptile}

Mauller

LGTM

Mauller · 2026-10-28T08:30:42Z

 													 UnsignedInt lineColor )
 {
-	setup2DRenderState(nullptr, DRAW_IMAGE_ALPHA, FALSE);
+	setup2DRenderState(nullptr, DRAW_IMAGE_ALPHA, FALSE, 4, 6);


it might help to have some constants for the 4 and 6 instead of magic numbers.

Probably want something like verticesPerQuad etc.

Done, added named constants for the quad and triangle counts.

tintinhamans mentioned this pull request Oct 12, 2026

bugfix(w3dwater): Skip rivers that overflow the dynamic index buffer #3489

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Skyaero42 reviewed Oct 13, 2026

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Comment thread Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DDisplay.cpp

Mauller reviewed Oct 13, 2026

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Comment thread GeneralsMD/Code/Libraries/Source/WWVegas/WW3D2/render2d.h Outdated

tintinhamans force-pushed the arctic/fix/render2d-batch-overflow branch from 1bdda9d to 1714002 Compare October 13, 2026 07:55

macroscopeapp Bot reviewed Oct 13, 2026

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Comment thread GeneralsMD/Code/Libraries/Source/WWVegas/WW3D2/render2d.cpp Outdated

Mauller approved these changes Oct 16, 2026

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xezon requested changes Oct 16, 2026

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Comment thread Generals/Code/Libraries/Source/WWVegas/WW3D2/render2d.cpp Outdated

Comment thread Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DDisplay.cpp Outdated

Comment thread Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DDisplay.cpp Outdated

tintinhamans force-pushed the arctic/fix/render2d-batch-overflow branch from 1714002 to fd459dd Compare October 18, 2026 02:30

tintinhamans requested review from Mauller and xezon October 18, 2026 02:30

tintinhamans force-pushed the arctic/fix/render2d-batch-overflow branch 2 times, most recently from 6b298b2 to d13fd9a Compare October 23, 2026 07:37

tintinhamans requested a review from Skyaero42 October 23, 2026 07:52

coderabbitai Bot mentioned this pull request Oct 24, 2026

fix(render): Correct river shroud sampling and cull off-screen geometry #3590

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Mauller reviewed Oct 27, 2026

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Comment thread Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DDisplay.cpp Outdated

tintinhamans force-pushed the arctic/fix/render2d-batch-overflow branch from d13fd9a to 13462fe Compare October 27, 2026 10:19

Mauller reviewed Oct 28, 2026

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fix(render2d): flush batched draws before dynamic buffer overflow

c588bcf

tintinhamans force-pushed the arctic/fix/render2d-batch-overflow branch from 13462fe to c588bcf Compare October 29, 2026 23:18

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bugfix(render2d): Flush batched 2D draws before they overflow the dynamic buffers - #3487

bugfix(render2d): Flush batched 2D draws before they overflow the dynamic buffers#3487
tintinhamans wants to merge 1 commit into
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tintinhamans:arctic/fix/render2d-batch-overflow

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Confidence Score: 5/5

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