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Wassim SAMADandClaude Opus 4.7 11015ea1ed wiki: document parametric-node + move-tool pitfalls

Captures the gotchas surfaced while building the shelf so the next
contributor adding a registry-driven kind doesn't rediscover them.

`node-definitions.md` — new Pitfalls section + a rule that builders
must emit local-space children. Covers:
- `<GeometrySystem>` must NOT mutate `group.position` / `group.rotation`
  after rebuild (the renderer binds them via JSX prop).
- Tag geometry-built children with `userData.__fromGeometry` so
  rebuilds don't dispose React-mounted hosted children (the
  item-disappears-on-shelf bug).
- Previews must clone materials before mutating them when the kind's
  builder caches at module scope.
- Host kinds need a `children: z.array(...).default([])` field on their
  schema (and a migration patch for older scenes).

`tools.md` — three new move/placement pitfalls:
- Disable raycast on the moved mesh during drag, otherwise it captures
  the ray and starves `grid:move` → commits land at the stale start.
- Commit handlers listen to `grid:click` AND every `${kind}:click` to
  catch clicks that land on neighbouring 3D geometry first.
- Move tools must preserve the node's actual `rotation[1]` in
  `useLiveTransforms` — hardcoding 0 makes the node un-rotate mid-drag.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-19 15:12:27 -04:00

14 KiB

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Node definitions

The registry-driven composition model for node kinds.

Applies to: packages/core/src/registry/, packages/nodes/src/<kind>/, packages/viewer/src/components/viewer/{registered-systems.tsx,node-renderer.tsx}.

A node kind — shelf, wall, door, item, spawn, zone — is described by a NodeDefinition registered with nodeRegistry. The definition is plain data + lazy module references. Three optional fields decide how the kind appears in the scene at runtime; pick whichever combination matches the kind's needs.

This page covers those three fields. For the broader registry contract (schemas, capabilities, parametrics, MCP), see the registry plan in the private repo.

The three-checkbox model

Field	Purpose	Pick it when
`geometry?: (node, ctx) => Object3D`	Pure builder. Returns the meshes for this node.	The kind has parametric meshes that should rebuild when `updateNode` runs.
`renderer?: () => Promise<{ default: ComponentType<{ node }> }>`	Optional custom React component. Owns mesh creation.	The kind needs JSX-only features: `<Html>`, `useGLTF`, drei helpers, instancing, TSL shader materials, R3F portals.
`system?: () => Promise<{ default: ComponentType }>`	Optional per-frame component (`useFrame` returning `null`).	The kind needs imperative work per frame: animations, opacity transitions, named-mesh material poking, cross-kind dirty cascades.

The three fields are independent. There is no discriminator tag — presence is participation:

// shelf — pure geometry, no React, no per-frame work
export const shelfDefinition: NodeDefinition<typeof ShelfNode> = {
  // ...
  geometry: buildShelfGeometry,         // pure function in geometry.ts
}

// zone — built once via React (uses <Html>), animated per-frame via system
export const zoneDefinition: NodeDefinition<typeof ZoneNode> = {
  // ...
  renderer: () => import('./renderer'),  // composes <Html> + TSL materials
  system: { module: () => import('./system') },  // pokes uniforms per frame
}

// door — pure geometry + animation system
export const doorDefinition: NodeDefinition<typeof DoorNode> = {
  // ...
  geometry: buildDoorGeometry,
  system: { module: () => import('./animation') },  // advances operationState
}

Runtime: how the three fields are wired

Two framework components live in packages/viewer/src/components/viewer/:

<NodeRenderer> chooses what React mounts for a node:
1. If def.renderer is set → mount the custom renderer.
2. Otherwise → mount <ParametricNodeRenderer> — a thin empty <group> that registers with sceneRegistry, attaches pointer handlers via useNodeEvents, reads useLiveTransforms for drag overrides, and calls useScene.getState().markDirty(node.id) on mount.
<GeometrySystem> runs every frame:
1. Read dirtyNodes from useScene.
2. For each dirty node whose kind has def.geometry, look up the registered Group from sceneRegistry, build a GeometryContext, call def.geometry(node, ctx), dispose old children, attach the new ones, call clearDirty(id).
3. Kinds with no def.geometry are skipped — their custom def.renderer handles geometry on its own.

Per-kind def.system components mount alongside via <RegisteredSystems>. They run their own useFrame and can mark nodes dirty, address meshes by getObjectByName, advance animation state, etc. They run in addition to GeometrySystem, not instead of it.

`GeometryContext`

The second arg to geometry() is scene read access for builders that reference other nodes by ID. Most kinds ignore it.

type GeometryContext = {
  resolve: <N = AnyNode>(id: AnyNodeId) => N | undefined
  children: AnyNode[]    // resolved children of this node
  siblings: AnyNode[]    // same kind, same parent (drives wall mitering)
  parent: AnyNode | null
}

Shelf, spawn, item, column, fence segment — builder reads only node. ctx argument unused.
Wall — ctx.siblings for corner mitering with adjacent walls. ctx.children for cutout footprints (doors / windows hosted on the wall).
Door / window — ctx.parent for parent-wall thickness, so the frame depth lines up with the wall it's cut into.

GeometryContext exists so builders stay pure (no useScene import, no store mutation) and trivially unit-testable. The generic <GeometrySystem> builds ctx from the current scene snapshot once per dirty node; the cost is a few Map.get calls.

For level-scoped batch data (wall mitering across an entire level), ctx can be extended with ctx.levelData?.miters in a future revision — decided alongside the wall migration (Phase 3 of the registry plan).

Choosing the right combination

`geometry` only

Use this when the kind's meshes are a pure function of its node data. Shelf, spawn, item, column, fence segment, wall, door (geometry side), window (geometry side).

// packages/nodes/src/shelf/geometry.ts
export function buildShelfGeometry(node: ShelfNode): Group {
  const group = new Group()
  group.add(buildTopBoard(node))
  group.add(buildBracket(node, -1))
  group.add(buildBracket(node, +1))
  return group
}

// packages/nodes/src/shelf/definition.ts
export const shelfDefinition: NodeDefinition<typeof ShelfNode> = {
  // ...
  geometry: buildShelfGeometry,
}

No renderer.tsx, no system.tsx. The generic renderer mounts an empty group, the generic system fills it.

`renderer` only (no `geometry`, no `system`)

Use this when the kind composes its scene via JSX-only features and never needs imperative per-frame work. GLB-backed items, kinds that mount drei helpers.

// packages/nodes/src/<kind>/renderer.tsx
import { useGLTF } from '@react-three/drei'
import { useRegistry } from '@pascal-app/core'
import { useNodeEvents } from '@pascal-app/viewer'

const FurnitureRenderer = ({ node }: { node: FurnitureNode }) => {
  const ref = useRef<Group>(null!)
  const { scene } = useGLTF(node.asset.url)
  const handlers = useNodeEvents(node, 'furniture')
  useRegistry(node.id, 'furniture', ref)
  return <primitive object={scene.clone()} ref={ref} {...handlers} />
}

No def.geometry — geometry is the GLB. No def.system — there's nothing to animate.

`renderer` + `system` (no `geometry`)

Use this when the kind's tree contains React-only primitives (e.g. <Html>) and needs per-frame imperative work that doesn't rebuild geometry. Zone.

The renderer composes the tree once. The system pokes uniforms / opacity / transforms by name:

// renderer.tsx
<group ref={ref} {...handlers}>
  <Html name="label" position={centroid}>{node.name}</Html>
  <mesh name="floor" geometry={floorGeometry} material={floorMaterial} />
  <mesh name="walls" geometry={wallGeometry} material={wallMaterial} />
</group>

// system.tsx
useFrame(() => {
  sceneRegistry.byType.zone.forEach((id) => {
    const group = sceneRegistry.nodes.get(id) as Group
    const walls = group.getObjectByName('walls') as Mesh
    const material = walls.material as MeshBasicNodeMaterial
    material.userData.uOpacity.value = lerp(currentOpacity, targetOpacity, lerpSpeed)
  })
})

`geometry` + `system`

Use this when the kind has parametric geometry and extra responsibilities. Door, window.

geometry builds the visible meshes (frame, panels, hardware) as a pure function of node state + parent wall.
system advances animation (operationState), then calls markDirty(node.id) so the geometry system rebuilds on the next frame.

This split keeps animation state outside the node schema (it's ephemeral — lives in useInteractive) while still re-using the generic rebuild path.

Named meshes work in either pattern

Setting mesh.name = 'walls' is just a three.js property. A system targeting getObjectByName('walls') doesn't care whether the mesh was created in JSX (<mesh name="walls" />) or imperatively in a pure builder (mesh.name = 'walls'; group.add(mesh)). Use whichever fits the kind.

Migrating from custom renderer+system files to `def.geometry`

If your kind's current system only rebuilds geometry on dirty (no animations, no cascades, no material poking), it can collapse to a single def.geometry function:

Extract the imperative updateXMesh(node, group) from the system into a pure buildXGeometry(node): Group in packages/nodes/src/<kind>/geometry.ts.
Replace def.renderer with nothing — the framework's <ParametricNodeRenderer> covers it.
Replace def.system with def.geometry: buildXGeometry.
Delete renderer.tsx and system.tsx.

If the system also handles cascades, animations, or material updates, keep def.system and also set def.geometry — they run side by side.

Rules

Builders must be pure. No useScene import inside a def.geometry function. Read scene state via ctx. Mutating the store from a builder breaks idempotence.
Builders emit local-space children. The registered <group> is positioned/rotated by <ParametricNodeRenderer> via JSX (position={liveTransform?.position ?? node.position}). Builders return geometry as if the parent were at the origin — never bake the node's world position into vertex coords.
One mesh registered per node ID. The generic renderer registers a single <group> per node. If a custom renderer mounts multiple meshes, register the parent group (or whichever object the system needs to address).
Custom systems run in addition to the generic system, not instead of it. A kind with def.geometry + def.system will see the generic system rebuild children on dirty AND the per-kind system run its useFrame. Plan priorities accordingly: door-animation runs at priority 2, geometry rebuild at priority 3.
Dispose on rebuild. The generic system disposes the previous children's geometry + material before swapping. Custom systems that imperatively add children must dispose what they replace, or accept the GPU-memory cost.
def.renderer overrides the generic renderer. Once you set it, you own the mount — <ParametricNodeRenderer> is not invoked. The generic geometry system still runs for the kind if def.geometry is set, so a custom renderer can register an empty group and let the system fill it.

Pitfalls

`<GeometrySystem>` must not mutate `group.position` / `group.rotation`

ParametricNodeRenderer binds <group position={liveTransform?.position ?? node.position}> and the matching rotation via JSX. React only re-applies the prop when its underlying value changes. If the geometry system imperatively zeroes group.position after a rebuild — as legacy per-kind systems used to — R3F has no reason to re-render on the next tick and the group stays at the origin. Symptom: the node visually snaps to (0, 0, 0) whenever its geometry rebuilds (move commit, dimension change, paint).

The contract is the other way around now: builders produce local-space children; the renderer owns the transform; the system only swaps children.

Tag geometry-built children with `userData.__fromGeometry`

A registered <group> can host two kinds of children: meshes the geometry builder created (boards, posts, dividers) and React-rendered hosted nodes (items reparented onto a shelf surface). When the system rebuilds, it must dispose only the previous geometry pass — disposing React-mounted children would tear out their meshes mid-mount, leaving the hosted node in scene state but invisible. Symptom: dragging an item onto a shelf makes the item disappear and never come back.

<GeometrySystem> tags every child returned by the builder with userData.__fromGeometry = true and disposeChildren only removes/disposes children carrying the marker. Custom systems that imperatively add children to a registered group must follow the same convention if hosted children are possible.

Previews must clone materials before mutating them

def.preview typically calls the kind's geometry builder, then walks the resulting meshes and sets material.transparent = true; material.opacity = 0.5 for a ghosted look. If the builder caches materials at module scope — and shelf, item, and most cache-friendly kinds do, keyed on material / materialPreset — every committed instance of the kind in the scene shares one material instance. Mutating it in the preview leaks the translucency into every real node that uses the default material; placed shelves render see-through, placed items lose their opacity, etc.

The fix is to clone in the preview, mutate the clone, and reassign mesh.material to the clone. On unmount, dispose only the clones — never the original returned by the builder, which other nodes still reference. nodes/src/shelf/preview.tsx is the reference implementation.

Host kinds need a `children` field on the schema

If your kind declares relations.hosts: [...], add children: z.array(...).default([]) to the schema. useScene.createNode(child, parentId) writes child.parentId = parentId and appends child.id to parent.children. Without the field, the parent-side write is a no-op — <ParametricNodeRenderer>'s n.children.map(...) then has nothing to mount and the host renderer never sees the new child. Symptom: hosted node lives in useScene.nodes but no React mount fires, so the host's tree-node sidebar entry is empty and the 3D scene shows nothing where the host should pick it up.

Migrations matter: if your kind shipped before hosting was added, patch existing nodes in migrateNodes so Array.isArray(node.children) holds for every loaded scene before the renderer reads it.

14 KiB Raw Blame History

Node definitions

The three-checkbox model

Runtime: how the three fields are wired

GeometryContext

Choosing the right combination

geometry only

renderer only (no geometry, no system)

renderer + system (no geometry)

geometry + system