zwitschi
72705268b5
Populated from the arc42-template (EN/adoc) with project-specific content
across all 12 sections:
1. Introduction and Goals — requirements overview, quality goals, stakeholders
2. Architecture Constraints — technical (engine, collision, coordinates),
organisational (squash-merge, visual review, provenance), conventions
3. Context and Scope — business and technical context tables
4. Solution Strategy — technology decisions, top-level decomposition,
quality achievement approach
5. Building Block View — Gameplay (6 C++ classes), Site (7 meshes + 7
materials), Facades (9 buildings), Art Pipeline, QA & Review; Level 2
white boxes for input flow and collision model
6. Runtime View — walk, screenshot capture, QA self-test, build/import
pipeline scenarios
7. Deployment View — dev workstation and packaged build infrastructure
8. Cross-cutting Concepts — coordinate system, collision model, lighting,
materials, data provenance, QA harness
9. Architecture Decisions — 7 ADRs (dynamic lighting, UE materials,
C++ collision helper, grounded reset, core ticker, Y convention,
headless Blender)
10. Quality Requirements — overview table + 7 measurable scenarios
11. Risks and Technical Debts — 5 risks, 2 debts with mitigations
12. Glossary — 16 domain-specific terms
Master document: Docs/Architecture/architecture.adoc
Config: Docs/Architecture/config.adoc
47 lines
2.4 KiB
Plaintext
47 lines
2.4 KiB
Plaintext
ifndef::imagesdir[:imagesdir: ./images]
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[[section-concepts]]
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== Cross-cutting Concepts
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=== Coordinate system and scale
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* **Source CRS**: EPSG:26911 (UTM zone 11N). Local origin recorded in `Geo/`.
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* **Blender**: metres. East → +X, north → +Y (Blender convention).
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* **Unreal**: centimetres. East → +X, north → **−Y** (confirmed from street mesh: `Sidewalk_North` Y −1912..−1053, `Sidewalk_South` Y +718..+1447).
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* **Conversion**: every exporter calls the metre→centimetre function. Import presets (`ue_metric_v1`, `ue_character_v1`) are named and repeatable.
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Rule: place a building only against a neighbour or street mesh, never in isolation.
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=== Collision model
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* Site meshes (road, sidewalks, kerbs, crossing): `STATIC` mobility, `BlockAll` collision profile.
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* Terrain: `STATIC`, `CTF_UseComplexAsSimple` (forced by `UGigLineAssetTools` at build time, saved on the asset — the flag lives on the `UStaticMesh`/`UBodySetup`, not the map).
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* Buildings: `STATIC`, simple collision (convex hull from mesh).
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* Rule: the collision flag must be saved on the asset. Saving only the `.umap` silently reverts it.
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=== Lighting
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* Dynamic-only: `r.AllowStaticLighting=False`. All lights are `MOVABLE`.
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* Fixed daytime rig: directional light (sun, −62° pitch), sky light, exponential height fog, post-process volume with fixed exposure.
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* Rationale: avoids "LIGHTING NEEDS TO BE REBUILT" warnings; no bake step; the scene never changes time of day.
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=== Materials
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* All materials authored in Unreal, not carried from Blender (FBX import loses diffuse colours).
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* World-space-noise blend nodes for cheap procedural variation (asphalt grain, concrete speckle, stucco roughness).
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* Instance parameters where tunable (e.g. wetness, ageing).
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=== Geographic data provenance
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* OSM extract is layout data only — not authoritative for façade, height, or pavement detail.
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* DEM from 3DEP 1 m; elevation verified against cross-sections in `Geo/verification/`.
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* Reference photography (local, gitignored) drives manual façade work.
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* In-game ODbL attribution drawn by `AGigLineHUD` every frame, bottom-left.
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=== QA harness
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* `-qaselftest`: core ticker (not world timer) so pause cannot freeze the test that proves pause works.
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* `GigLine SIM` / `GigLine GROUND`: TEMP diagnostic logging, to be removed before release tag.
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* Screenshot approval: human must tick `Screenshots/README.md` before visual work is marked done.
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