# Solution Strategy

## Technology decisions

- **Unreal Engine 5.8.4** for rendering, World Partition, physics (Chaos), and the Enhanced Input system. Chosen for its Linux support, open C++ source, and real-time rendering quality.

- **Blender 5.2 LTS** for all 3D modelling, UV work, and collision mesh authoring. Driven headlessly via `bpy` Python scripts, not MCP.

- **QGIS 4.2.3** for geographic data cleanup, coordinate conversion (EPSG:26911), and DEM preparation.

- **Blosm 2.7.28** for OSM building and street blockouts inside Blender (layout data only — not authoritative façade, height, or pavement detail).

- **MPFB 2.0.18** for human base meshes and baked materials (NPCs in `0.2.0+`).

## Top-level decomposition

The system is a single Unreal game module (`GigLine`) with no plugins beyond `EnhancedInput`. Content is organised by domain under `/Game/Hollywood/`:

- `Site/` — terrain, road, sidewalks, kerbs, crossing markings, site materials

- `ElCapitan/` — hero façade mesh and materials

- `Frontage/` — south-side block building meshes

- `North/` — north-side building meshes

- `Input/` — Enhanced Input actions and mapping context

All modelling and geographic processing live outside the game project in `Art/`, `Geo/`, and `Tools/`. The `Game/` directory contains only engine-ready content and C++ source.

## Quality achievement

- **Performance**: dynamic-only lighting (no build step, no static shadow maps), world-space-noise materials (cheap procedural variation), minimal overdraw (simple street-level geometry).

- **Walkability**: complex-as-simple collision on terrain (C++ helper forces the flag on the asset), block-all collision on every site mesh, swept transect QA verifies zero raycast holes.

- **Fidelity**: geographic data verified before modelling (footprints, bounds, DEM); building placement checked against street mesh, never in isolation; reference photography drives façade work.

- **Reproducibility**: pinned toolchain in `Docs/toolchain.md`, named export presets, `Tools/check-lfs.sh` gate, fresh-checkout build procedure in `Docs/build.md`.