racing_source_audit.md

Racing Game Kit source-to-source audit

This audit covers the unchanged XNA 4 source snapshot retained at:

/rv/tmp/samples/SAMPLE-152-XNA-4-Racing-Game-Kit-master/xna4-original/

Its 325-file SHA-256 manifest is evidence/xna4-original.sha256. The selected game project contains 58 C# files. The canonical content project contains 57 .X, 129 .TGA, 11 .PNG, two .DDS, ten .fx, 28 .wav, one .xap, three .Track, ten .CombiModel and one .data source. The runtime input is the unchanged XNA Game Studio 4 output, not the modern repository: 339 XNBs plus the XGS/XSB/XWB and 14 raw data files.

File mapping

Direct means the logical class and algorithms remain in the same named C++ owner. Factored means a process-static C# owner was split into explicit game-owned C++ dependencies without a second behavior path. Integrated means the source behavior is retained by the named rendering/platform owner rather than by an otherwise empty wrapper.

Original XNA 4 file	CNA Samples implementation	Classification
GameLogic/BasePlayer.cs	GameLogic/BasePlayer.*	Direct
GameLogic/CarPhysics.cs	GameLogic/CarPhysics.*, CarControlState.*	Factored; deterministic environment replaces process statics
GameLogic/ChaseCamera.cs	GameLogic/ChaseCamera.*	Direct
GameLogic/Input.cs	GameLogic/Input.*	Direct; real keyboard/mouse/gamepad provider plus injectable test source
GameLogic/Physics/SpringPhysicsObject.cs	GameLogic/Physics/SpringPhysicsObject.*	Direct
GameLogic/Player.cs	GameLogic/Player.*	Direct with explicit environment
GameLogic/Replay.cs	GameLogic/Replay.*	Direct, including the original replayFileFound quirk and binary layout
GameLogic/ScreenshotCapturer.cs	GameLogic/ScreenshotCapturer.*	Direct XNA component and PrintScreen/JPEG path
GameScreens/CarSelection.cs	GameScreens/CarSelection.*	Direct
GameScreens/GameScreen.cs	GameScreens/GameScreen.*	Direct
GameScreens/Help.cs	GameScreens/Help.*	Direct
GameScreens/Highscores.cs	GameScreens/Highscores.*	Direct
GameScreens/IGameScreen.cs	GameScreens/IGameScreen.hpp	Direct interface
GameScreens/LoadingScreen.cs	GameScreens/LoadingScreen.*	Direct; stages run cooperatively on the graphics owner thread
GameScreens/MainMenu.cs	GameScreens/MainMenu.*	Direct
GameScreens/Options.cs	GameScreens/Options.*	Direct
GameScreens/SplashScreen.cs	GameScreens/SplashScreen.*	Direct
GameScreens/TrackSelection.cs	GameScreens/TrackSelection.*	Direct
GameSettings.cs	Properties/GameSettings.*, Serialization/XmlSerializationAdapters.hpp	Direct wire format; compile-time XML metadata replaces reflection
Graphics/BaseGame.cs	RacingGameManager.*, Graphics/ResolutionMapper.*, game-owned renderers	Factored process-static owner
Graphics/LensFlare.cs	Graphics/LensFlare.*	Direct
Graphics/LineManager2D.cs	Graphics/LineManager2D.*, UIRenderer.*	Direct
Graphics/LineManager3D.cs	Graphics/LineManager3D.*	Direct dormant branch; authentic effect is GPU-tested
Graphics/Material.cs	Graphics/Material.*	Direct
Graphics/MeshRenderManager.cs	Graphics/MeshRenderManager.*	Direct grouping/order logic
Graphics/Model.cs	Graphics/Model.*, Rendering/CarRenderer.*, LandscapeObjectRenderer.*	Factored model policy and concrete draw owners
Graphics/PlaneRenderer.cs	Rendering/StaticTrackScene.* city-ground mesh	Integrated exact two-triangle plane
Graphics/TangentVertex.cs	Graphics/TangentVertex.*	Direct 44-byte runtime layout
Graphics/Texture.cs	Graphics/Texture.*	Direct XNB texture wrapper
Graphics/TextureFont.cs	Graphics/TextureFont.*	Direct
Graphics/TextureFontBigNumbers.cs	Graphics/TextureFontBigNumbers.*	Direct
Graphics/UIRenderer.cs	Graphics/UIRenderer.*	Direct atlases, text, trophies and debug FPS branch
Helpers/ColorHelper.cs	Helpers/ColorHelper.*	Direct
Helpers/Directories.cs	RacingRunConfiguration, ContentManager::RootDirectory, CNA storage	Integrated platform paths
Helpers/FileHelper.cs	Replay.*, GameSettings.*, ScreenshotCapturer.*, CNA TitleContainer/storage	Integrated stream/storage operations
Helpers/Log.cs	Helpers/Log.*	Direct isolated-storage log and 2 MiB rotation
Helpers/RandomHelper.cs	Helpers/RandomHelper.*	Direct
Helpers/Vector3Helper.cs	Helpers/Vector3Helper.*	Direct
Landscapes/Landscape.cs	Landscapes/Landscape.*, Rendering/StaticTrackScene.*	Factored CPU generation and GPU owner
Program.cs	Program.cpp	Direct entry point
Properties/AssemblyInfo.cs	CMakeLists.txt, program/window metadata	Integrated build metadata
RacingGameManager.cs	RacingGameManager.*	Direct game/screen/race owner
Shaders/PostScreenGlow.cs	Shaders/PostScreenGlow.*	Direct authentic five-pass effect
Shaders/PostScreenMenu.cs	Shaders/PostScreenMenu.*	Direct authentic four-pass effect
Shaders/PreScreenSkyCubeMapping.cs	Rendering/StaticTrackScene.* sky draw	Integrated authentic sky effect/cube/model
Shaders/RenderToTexture.cs	Shaders/RenderToTexture.*	Direct
Shaders/ShaderEffect.cs	Graphics/Model.* and concrete renderers' shared XNA Effect binding	Integrated common parameter/technique behavior
Shaders/ShadowMapBlur.cs	Rendering/ShadowMapRenderer.*	Integrated authentic blur passes
Shaders/ShadowMapShader.cs	Rendering/ShadowMapRenderer.*	Integrated caster/receiver passes
Shaders/VBScreenHelper.cs	Shaders/VBScreenHelper.*	Direct
Sounds/Sound.cs	Sounds/Sound.*	Direct XACT banks, cues, categories and five-gear behavior
Tracks/GuardRail.cs	Tracks/GuardRailGeometry.*, StaticTrackScene.*	Factored CPU geometry and GPU owner
Tracks/Track.cs	Tracks/Track.*, TrackGeometry.*	Factored CPU geometry and runtime owner
Tracks/TrackColumns.cs	Tracks/TrackColumnsGeometry.*, StaticTrackScene.*	Factored CPU geometry and GPU owner
Tracks/TrackCombiModels.cs	Tracks/TrackCombiModels.*	Direct XML data model
Tracks/TrackData.cs	Tracks/TrackData.*	Direct XML data model
Tracks/TrackLine.cs	Tracks/TrackLine.*	Direct spline/helper generation
Tracks/TrackVertex.cs	Tracks/TrackVertex.*	Direct data model

Audited C++ mechanics

• The original content identifiers and ContentManager::Load<T> routes remain. There is no GLB, glTF, .material or loose-image runtime path.
• XNB model vertices retain their processor-authored 56-byte tangent/binormal declaration. Runtime-generated TangentVertex remains a separate 44-byte layout; neither is coerced into the other.
• The original worker loading order is visible unchanged, but GPU resources are created cooperatively on CNA's graphics owner thread. This is the required thread-affinity translation, not a content bypass.
• Process-static C# state is held by one RacingGameManager; deterministic qualification dependencies are injected only at construction. The product executable always creates the real CNA input provider.
• Screenshot enumeration and output use the same CNA storage-container root so the original relative path remains confined on every supported platform.
• The Release-only render exception budget, debug-only FPS toggle, adaptive view distance, isolated Log.txt, screenshot component and device-reset resource recreation are retained.
• LineManager3D has no callers outside original BaseGame in the selected source, and no product class submits a world-space line. Its retained branch nevertheless loads LineRendering.xnb, submits both overloads and resets its frame collection in the GPU harness.

Observable parity evidence

• Control/simulation/audio-event trace: all 753 FNA/CNA records agree, with a measured maximum camera difference of 16 ULP. The trace includes better/worse checkpoint cues, victory/loss selection and gear stop.
• Track/replay: 79/79 cumulative FNA/CNA records agree.
• Static render: normalized RMSE 0.002230, with 99.0503% of channels within two values between the FNA and CNA reference captures.
• Authentic XACT: all 27 source cue names load from the unchanged XGS/XSB/XWB; screen flow starts menu/selection/race cues and Gear1, while the natural race outcome emits its cue and stops the looping gear sound.

The release/license inventory is separate in racing_release_gate.md. Runtime qualification does not imply permission to redistribute the retained Microsoft assets.