gig-line/Docs/Architecture/04_solution_strategy.md

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.