# OpenSpec Change: enterprise-gaming-r3f-buildings

- **Change ID**: enterprise-gaming-r3f-buildings
- **Package**: `@suaveplan/r3f-buildings`
- **Category**: gaming/scene
- **Target path**: `gaming/scene/r3f-buildings`
- **Status**: PROPOSED
- **Date**: 2026-04-24
- **Reference spec**: `/mnt/s/web/suaveplan/enterprise/r3f-buildings.md`

---

## Summary

Deliver `@suaveplan/r3f-buildings` on the genesis branch from scratch at enterprise quality. The package provides instanced city-scale 3D building and road rendering for React Three Fiber. A `BuildingTileLoader` fetches building footprint + height data (GeoJSON or procedural tile); `InstancedBuildings` renders all buildings in a tile as a single draw call using `InstancedMesh` with per-instance world transform; `Roads` extrudes road segments as ribbon geometry. LOD degrades to billboard sprites at far distances. Genesis adds structured errors, OTel draw-call counter, and 100% coverage.

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## Available workspace deps

`@suaveplan/error`, `@suaveplan/types`, react, `@react-three/fiber`, `@react-three/drei`, three.

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## Public API surface

```ts
function Buildings(props: BuildingsProps): JSX.Element
// tiles, lodDistance, meshes

function Roads(props: RoadsProps): JSX.Element
// segments, width, material

function useBuildings(): BuildingsCon```text

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## File layout

```text
gaming/scene/r3f-buildings/
  package.json / tsconfig.json / vitest.config.ts
  src/
    index.ts / error-codes.ts
    types/common.ts + md
    core/
      tile-loader/ (ts + md + test + index)
      instancer/ (ts + md + test + index)
    components/
      Buildings/ (tsx + md + test + stories + index)
      Roads/ (tsx + md + test + stories + index)
    hooks/use-buildings.ts + md + test
  tests/integration.test.ts
```