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Racing Milestone 4 — static track scene

Result

Milestone 4 is complete on 2026-09-03. CNA now renders the first representative Racing scene from the original XNA 4 raw track/landscape inputs and authentic XNA Game Studio 4.0 XNB products. No GLB, glTF, modern material, loose texture, shader rewrite or sample-local content decoder is present.

The cumulative public harness is 102/102 PASS in Debug and ASan/UBSan. The model-free static capture is structurally the same as the authoritative FNA/OpenGL capture: normalized RMSE 0.002230, 99.0503% of RGB channels within two 8-bit values and maximum channel delta 19.

Frozen revisions and environment

  • CNA: af0f4f1964ed12aef1b63d5083e7293c49c3a393
  • cna-samples Milestone 4 starting revision: 96e2bc3
  • cna-samples pre-closure revision: b98d121c1379473478c5fd2e0d894acf64d8a3a2
  • sharp-runtime: 6baf0925e0bf7805a363836deed90543d26f6d28
  • FNA managed source/assembly: b35512475ed7980169574d2c40927381c1764d5a
  • FNA3D: 32401479a3ab5bd6b2e7f786e87bf4166aa03b0f
  • modern Racing behavior oracle: d8092633e4e43e014ff168d8e913a9373538b851
  • CNA renderer: OPENGL33, HiDef, Mesa llvmpipe OpenGL 4.5 core
  • FNA renderer: FNA3D OpenGL, Mesa llvmpipe OpenGL 4.5 compatibility, MojoShader glsl120

Original data and CPU structure

The port reads the unchanged TrackBeginner.Track, TrackAdvanced.Track, TrackExpert.Track, ten .CombiModel files and LandscapeHeights.data. Its 44-byte runtime TangentVertex remains deliberately separate from the authentic processor-authored 56-byte XNB model vertex layout.

The authoritative C# oracle and C++ probe agree bit-for-bit across 64 record groups:

  • 66,049 landscape vertices and 393,216 indices;
  • every generated field for all three closed track splines;
  • road, road-back and tunnel vertices/indices;
  • both guard-rail meshes and all holder transforms;
  • every column mesh and RoadColumnSegment position;
  • all road-helper ranges, neutral-object matrices and ten combinations.

For TrackBeginner, the visible scene specifically retains 6,660 road vertices, 11,339 vertices per guard rail, 224 left holders, 231 right holders and 101 column positions. Re-running the original Track oracle after adding the renderable scene still reports:

RACING_TRACK_ORACLE_COMPARISON=PASS records=64 COLUMN=3 COMBI=10
FIELDHASH=3 GUARD=6 HELPER=32 LANDSCAPE=1 PHASEHASH=3 ROAD=3 TRACK=3

GPU scene

StaticTrackScene owns the original CPU objects and RAII vertex/index buffers for terrain, road, road back, tunnels, both rails and columns. It loads unchanged XNB identifiers for:

  • Shaders/NormalMapping, Shaders/LandscapeNormalMapping and Shaders/PreScreenSkyCubeMapping;
  • the original landscape/detail, road, road-back, tunnel, guard-rail and cement textures/normal maps;
  • Textures/SkyCubeMap and the stock-processor Models/Cube.

Technique selection, material colors, specular power, sky color and the normalized original gameplay light (8500,-7250,15000) follow the original sources. The standard final capture additionally submits authentic custom-processor XNB models GuardRailHolder, RoadColumnSegment and Banner6 using qualified placements.

Independent FNA image oracle

The FNA project reuses the linked original TangentVertex, TrackData, TrackLine, TrackVertex and TrackCombiModels sources plus the already-qualified oracle landscape/geometry builders. It loads the authentic textures, cube map and Cube XNB. As in Milestone 3, only FNA's renderer-side Effect bytes come from the pinned modern repository because unpatched FNA MojoShader cannot parse an unused legacy shader in the authentic full Effect graph. Those .efb files are behavior-oracle inputs only; they are not copied into or loaded by CNA.

The comparison intentionally captures CNA immediately before the three custom model submissions. This gives FNA and CNA identical scene contents while the final CNA capture separately proves the representative authentic models. The committed comparator enforces RMSE at most 0.01 and at least 97% of channels within two values. Frozen output is substantially tighter:

RACING_STATIC_SCENE_COMPARISON=PASS width=320 height=180
rmse=0.002230 channelsWithin2=0.990503 maxChannelDelta=19

PPM SHA-256 values:

  • CNA Debug/ASan/LSan base scene: 70d110a08e2a080d1e7a30c5a883677a22412b53b01230825dcebd7b110cbb80
  • FNA base scene: 3af1c2f8369bbbdc3d1630a293deb548252c4b1be95ffc8a4b6db9b15d731916

Qualification and remaining scope

samples/RacingGameHarness/scripts/qualify-milestone1.sh is the cumulative entry point and caps compilation at eight jobs. It completed:

  • Debug OPENGL33 build/run with real synthetic X11 keyboard/mouse input: 102/102;
  • ASan/UBSan build/run with leak detection disabled: 102/102, no finding;
  • LSan classification: 102/102, only the already-known 100,956 bytes rooted wholly in external Mesa libGLX_mesa frames;
  • FNA/OpenGL static-scene build/run: RESULT PASS;
  • FNA/CNA Debug and ASan image comparisons: PASS;
  • git diff --check: PASS before commit.

Evidence roots:

  • evidence/cna-opengl33/milestone4/
  • evidence/fna-static-scene-oracle/
  • diagnostics/ for the exact CPU oracle reports.

No CNA or sharp-runtime change was required for this final GPU slice. The earlier general fixes used by Milestone 4 remain independently committed upstream. Milestone 5 may now begin with car/player state, wheel hierarchy, chase camera and a logical desktop input snapshot. Full decorative auto-population and combination model rendering remain scheduled for Milestone 7, while checkpoint gameplay belongs to Milestone 6.