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editor/wiki/architecture/renderers.md
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Wassim SAMADandClaude Opus 4.7 7b946ce8b7 wiki: add node-definitions doc for three-checkbox composition model
New page covering the geometry/renderer/system trio that registry-driven
kinds opt into. Documents:

- The three optional fields on NodeDefinition and when each applies
- Generic <GeometrySystem> + <ParametricNodeRenderer> runtime
- GeometryContext shape (resolve / children / siblings / parent)
- Combination matrix for shelf / spawn / zone / door / window / GLB items
- Migration recipe from custom renderer+system files to def.geometry
- Rules around purity, dispose-on-rebuild, register-once

renderers.md and systems.md gain "prefer registry-driven" banners and
link out to the new page. Architecture README adds the page to the
index so review-architecture skill picks it up.

The pattern was validated by the shelf spike: inline-JSX geometry was
visibly laggy on parametric edits; moving to a per-kind system reading
dirtyNodes (mirroring door/wall/item) restored smoothness. The three-
checkbox model generalises that win so most future kinds need only a
pure geometry function.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-15 08:29:54 -04:00

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3.1 KiB
Markdown

# Renderers
*Node renderer pattern in `packages/viewer`.*
Applies to: `packages/viewer/**`.
Renderers live in `packages/viewer/src/components/renderers/`. Each renderer is responsible for one node type's Three.js geometry and materials — nothing else.
> **For registry-driven kinds, the default is no custom renderer.** Set `def.geometry` instead and the framework mounts a generic renderer + geometry system for you. See [node-definitions.md](node-definitions.md). The pattern below applies to kinds that *do* need a custom renderer (GLB, `<Html>`, drei, instancing, shader materials).
## Dispatch Chain
```
<SceneRenderer> — iterates rootNodeIds from useScene
└─ <NodeRenderer> — switches on node.type, renders the matching component
└─ <WallRenderer> — (or SlabRenderer, DoorRenderer, …)
```
See `packages/viewer/src/components/renderers/scene-renderer.tsx` and `packages/viewer/src/components/renderers/node-renderer.tsx`.
## Renderer Responsibilities
A renderer **should**:
- Read its node from `useScene` via the node's ID
- Register its mesh(es) with `useRegistry()` so other systems can look them up
- Subscribe to pointer events via `useNodeEvents()`
- Render geometry and apply materials based on node properties
A renderer **must not**:
- Run geometry generation logic (that belongs in a System)
- Import anything from `apps/editor`
- Manage selection state directly (use `useViewer` for read, emit events for write)
- Perform expensive per-frame calculations in the component body
## Example — Minimal Renderer
```tsx
// packages/viewer/src/components/renderers/my-node/index.tsx
import { useRegistry } from '@pascal-app/core'
import { useNodeEvents } from '../../hooks/use-node-events'
import { useScene } from '@pascal-app/core'
export function MyNodeRenderer({ node }: { node: MyNode }) {
const ref = useRef<Mesh>(null!)
useRegistry(node.id, 'my-node', ref) // 3 args: id, type, ref — no return value
const events = useNodeEvents(node, 'my-node')
return (
<mesh ref={ref} {...events}>
<boxGeometry args={[node.width, node.height, node.depth]} />
<meshStandardMaterial color={node.color} />
</mesh>
)
}
```
## Adding a New Node Type
For new kinds, prefer the registry-driven model in [node-definitions.md](node-definitions.md). The legacy steps below apply only when a kind needs a custom React renderer (GLB loaders, `<Html>` portals, etc.) **and** lives in `packages/viewer` rather than `packages/nodes/<kind>`:
1. Create `packages/viewer/src/components/renderers/<type>/index.tsx`
2. Add a case to `NodeRenderer` in `node-renderer.tsx`
3. Add the corresponding system in `packages/core/src/systems/` if the node needs derived geometry
4. Export from `packages/viewer/src/index.ts` if needed externally
## Performance Notes
- Use `useMemo` for geometry that depends on node properties — avoid recreating on every render.
- For complex cutout or boolean geometry, delegate to a System (e.g. `WallCutout`).
- Register one mesh per node ID; if a renderer spawns multiple meshes, use a group ref or pick the primary one for registry.