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neural: shared CPU training substrate + NeuralFunctionApproximator#498

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claude/evaluate-gpu-acceleration-hlh2X
Apr 18, 2026
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neural: shared CPU training substrate + NeuralFunctionApproximator#498
Krilliac merged 1 commit into
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claude/evaluate-gpu-acceleration-hlh2X

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@Krilliac Krilliac commented Apr 18, 2026

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Adds CpuNeuralTraining (backward pass + Adam/SGD + MSE/L1/Huber) and the NeuralFunctionApproximator facade so any CPU-heavy subsystem can opt in to a learned approximation. Refactors NeuralTextureCompressor off its inline SGD/backprop loop and replaces NeuralRadianceCache::Update's finite-diff MLP search with real analytical backprop + hash-grid input-gradient flow.

  • CpuNeuralTraining.{h,cpp}: Trainer class, gradient check, losses
  • NeuralFunctionApproximator.{h,cpp}: Configure/TrainOffline/TrainIncremental
  • NeuralWeights: .nnw bumped to v2 with optional Adam/SGD-momentum trailer (v1 files still load as optimizer.kind == None)
  • NRC: persistent Adam state across frames, one upload per batch instead of one per weight perturbation; ~100x faster training loop
  • NTC: TrainBlock reduced from ~130 LOC of inline backprop to ~40 LOC using the shared core + Adam
  • 13 new tests covering analytical-vs-numerical gradient check, Adam + SGD+momentum convergence on XOR, sine fit, NFA save/load round-trip, .nnw v1/v2 compat, NRC loss decreases

@claude
neural: shared CPU training substrate + NeuralFunctionApproximator
e507af0 
Adds CpuNeuralTraining (backward pass + Adam/SGD + MSE/L1/Huber) and the
NeuralFunctionApproximator facade so any CPU-heavy subsystem can opt in to
a learned approximation. Refactors NeuralTextureCompressor off its inline
SGD/backprop loop and replaces NeuralRadianceCache::Update's finite-diff
MLP search with real analytical backprop + hash-grid input-gradient flow.

- CpuNeuralTraining.{h,cpp}: Trainer class, gradient check, losses
- NeuralFunctionApproximator.{h,cpp}: Configure/TrainOffline/TrainIncremental
- NeuralWeights: .nnw bumped to v2 with optional Adam/SGD-momentum trailer
  (v1 files still load as optimizer.kind == None)
- NRC: persistent Adam state across frames, one upload per batch instead
  of one per weight perturbation; ~100x faster training loop
- NTC: TrainBlock reduced from ~130 LOC of inline backprop to ~40 LOC
  using the shared core + Adam
- 13 new tests covering analytical-vs-numerical gradient check, Adam +
  SGD+momentum convergence on XOR, sine fit, NFA save/load round-trip,
  .nnw v1/v2 compat, NRC loss decreases
@Krilliac
Krilliac merged commit 85cdb8a into Working Apr 18, 2026
37 of 42 checks passed
@Krilliac
Krilliac deleted the claude/evaluate-gpu-acceleration-hlh2X branch April 18, 2026 16:51
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Code Coverage (GCC + lcov)

Utils/StringUtils.h                            |18.1%   116| 0.0%  21|    -    0
Utils/Telemetry.h                              |20.6%   136| 0.0%  23|    -    0
Utils/ThreadDebugger.h                         |11.6%   199| 0.0%  23|    -    0
Utils/ThreadSafeQueue.h                        |27.5%    40| 0.0%  11|    -    0
Utils/Timer.cpp                                |19.4%    36| 0.0%   7|    -    0
Utils/Timer.h                                  | 100%     2| 0.0%   2|    -    0
Utils/TimerManager.h                           |18.6%   102| 0.0%  19|    -    0
Utils/Tween.h                                  |26.3%    38| 0.0%   6|    -    0
Utils/UUID.h                                   |43.2%    37| 0.0%  16|    -    0
Utils/Validate.h                               |    -     0|    -   0|    -    0
Utils/WineDetection.cpp                        |23.1%    39| 0.0%   9|    -    0

[/home/runner/work/SparkEngine/SparkEngine/SparkSDK/Include/Spark/]
IEngineContext.h                               |7300%     1| 0.0%   1|    -    0
IModule.h                                      | 800%     1| 0.0%   1|    -    0
ServiceInterfaces.h                            | 200%     3| 0.0%   3|    -    0
Version.h                                      |    -     0|    -   0|    -    0

[/home/runner/work/SparkEngine/SparkEngine/Templates/EmptyProject/Source/]
GameModule.h                                   |38.9%    18| 0.0%   6|    -    0

[/home/runner/work/SparkEngine/SparkEngine/Templates/FPSStarter/Source/]
GameModule.h                                   |36.0%    25| 0.0%   7|    -    0

[/home/runner/work/SparkEngine/SparkEngine/Templates/MultiplayerArena/Source/]
GameModule.h                                   |34.6%    26| 0.0%   7|    -    0

[/home/runner/work/SparkEngine/SparkEngine/Templates/PlatformerKit/Source/]
GameModule.h                                   |25.0%    32| 0.0%   7|    -    0

[/home/runner/work/SparkEngine/SparkEngine/Templates/RPGStarter/Source/]
GameModule.h                                   |37.5%    24| 0.0%   8|    -    0
================================================================================
                                         Total:|30.5% 35191| 0.0%  6k|    -    0

Per-Subsystem Coverage

Subsystem Lines Hit Coverage Threshold Status
AI 3716 942 25.3% 35% ❌
Animation 905 277 30.6% 35% ❌
Audio 0 0 0% 30% ✅
Camera 0 0 0% 40% ✅
Core 4877 2920 59.9% 40% ✅
ECS 426 213 50% 40% ✅
Editor 7413 3046 41.1% 25% ✅
GameModules 6621 3230 48.8% 30% ✅
Graphics 17891 9063 50.7% 30% ✅
Networking 3554 2351 66.2% 35% ✅
Physics 0 0 0% 35% ✅
Scripting 283 80 28.3% 30% ❌
Utils 9780 6050 61.9% 60% ✅

Total: 50.8% (28172/55466 lines)

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❌ CI Error Report

Failed jobs: clang-tidy, macos-Debug-OpenGL, macos-Release-Metal, macos-Release-OpenGL, windows-vs2022-Release
Errors: 1 | Test failures: 4 | Test warnings: 15 | Compiler warnings: 0

Build Errors

Other errors (1) 
clang++: error: linker command failed with exit code 1 (u e -v to  ee invocation) [macos-Debug-OpenGL, macos-Release-Metal, macos-Release-OpenGL]

Test Failures

Test Jobs
1/1 Test #1: SparkEngineTests .................***Failed 15.11 sec windows-vs2022-Release
::warning title=Flaky test: Integration_NetworkingECS_ReplicationLatencyJitterPredictionReconciliation::Integration_N... windows-vs2022-Release
[ FAILED ] Training_GradientCheckHuber (1.5ms, 1 assertions) windows-vs2022-Release
0% tests passed, 1 tests failed out of 1 windows-vs2022-Release

⚠️ Test Warnings (Known Flaky)

These tests are registered as known flaky and do not block the build:

Test Jobs
[17:33:26.008] [TID:3288] [WARN ] [Network ] RCON unknown command: nonexistent_cmd (DedicatedServer.cpp:573) windows-vs2022-Release
[17:33:26.023] [TID:3288] [WARN ] [Network ] NetBuffer::ReadUint8 — buffer overrun at pos 1 (size=1) (NetworkBuffer.c... windows-vs2022-Release
[17:33:26.043] [TID:3288] [WARN ] [AI ] BuildNavMeshWithRecast: empty geometry (RecastDetourBackend.cpp:35) windows-vs2022-Release
[17:33:26.043] [TID:3288] [WARN ] [AI ] NavMeshBuilder: Recast build failed, falling back to triangle-soup builder (N... windows-vs2022-Release
[17:33:26.043] [TID:3288] [WARN ] [Audio ] XAudio2 backend requested but no AudioEngine provided, falling back to Nul... windows-vs2022-Release
[ OK ] MaterialHandle_FindByN[17:33:26.061] [TID:3288] [WARN ] [Graphics ] No graphics backend available — falling ba... windows-vs2022-Release
[17:33:26.061] [TID:3288] [WARN ] [Graphics ] No graphics backend available — falling back to NullRHIDevice (headless... windows-vs2022-Release
[17:33:26.065] [TID:3288] [WARN ] [Editor ] Cannot host: userName is empty. (CollaborativeEditSession.cpp:454) windows-vs2022-Release
[17:33:26.065] [TID:3288] [WARN ] [Editor ] Already connected. (CollaborativeEditSession.cpp:459) windows-vs2022-Release
[17:33:26.068] [TID:3288] [WARN ] [Editor ] BroadcastEdit rejected: nodeId is empty. (CollaborativeEditSession.cpp:1108) windows-vs2022-Release
[17:33:26.068] [TID:3288] [WARN ] [Editor ] BroadcastEdit rejected: sourceEditor is not set. (CollaborativeEditSessio... windows-vs2022-Release
[17:33:26.069] [TID:3288] [WARN ] [Editor ] SetLocalSelection rejected: nodeId exceeds 255 chars (length=300). (Colla... windows-vs2022-Release
[17:33:31.637] [TID:3288] [WARN ] [Network ] Connection rejected for pending client 5: server full (4/4) (NetworkConn... windows-vs2022-Release
[17:33:31.638] [TID:3288] [WARN ] [Network ] Connection rejected for pending client 5: server full (4/4) (NetworkConn... windows-vs2022-Release
[17:33:31.639] [TID:3288] [WARN ] [Network ] Invalid packet magic 0x6A0E5CB3 (expected 0x5350524B) (NetworkManager.cp... windows-vs2022-Release

Updated: 2026-04-18T17:34:31Z — this comment is updated in-place, not duplicated.

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2 participants

@Krilliac @claude