Scene hierarchy: parentId with local positions, tree panel, reparenting and Parent node

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/core/graph/NodeRegistry.ts

@@ -12,10 +12,26 @@ export type Value = PropertyValue | EntityHandle | null;
 export interface EntityHandle {
   id: string;
   name: string;
+  /** Position local to `parent` (world position for top-level entities). */
   x: number;
   y: number;
   z: number;
   props: PropertyBag;
+  /** The entity this one is parented to; children move with their parent. */
+  parent: EntityHandle | null;
+}
+
+/** World position of a handle: its local position plus those of all ancestors. */
+export function worldPositionOf(handle: EntityHandle): { x: number; y: number; z: number } {
+  const result = { x: handle.x, y: handle.y, z: handle.z };
+  const seen = new Set<EntityHandle>([handle]);
+  for (let p = handle.parent; p && !seen.has(p); p = p.parent) {
+    result.x += p.x;
+    result.y += p.y;
+    result.z += p.z;
+    seen.add(p);
+  }
+  return result;
 }
 
 /**
@@ -26,7 +42,7 @@ export interface EntityHandle {
 export interface NodeContext {
   /** The behavior entity itself. */
   self: EntityHandle;
-  /** The scene object the behavior was attached to, if any. */
+  /** The behavior's parent object (the one the graph acts on), if any. */
   owner: EntityHandle | null;
   /** Mutable variable state of this behavior instance. */
   variables: PropertyBag;

src/core/graph/nodes.ts

@@ -1,5 +1,5 @@
 import type { PropertyDef } from '../properties/PropertySchema';
-import { asBoolean, asEntity, asNumber, asString, type PortDef, registerNode } from './NodeRegistry';
+import { asBoolean, asEntity, asNumber, asString, type PortDef, registerNode, worldPositionOf } from './NodeRegistry';
 
 /**
  * The built-in node set. Each entry is data + a `run` function; everything else (palette,
@@ -59,7 +59,17 @@ registerNode({
 // --- data: references --------------------------------------------------------------------
 
 registerNode({ type: 'Self', label: 'Self', category: 'data', description: 'This behavior object.', inputs: [], outputs: [obj('object')], params: [], run: (ctx) => ({ outputs: { object: ctx.self } }) });
-registerNode({ type: 'Owner', label: 'Owner', category: 'data', description: 'The object this behavior is attached to.', inputs: [], outputs: [obj('object')], params: [], run: (ctx) => ({ outputs: { object: ctx.owner } }) });
+registerNode({ type: 'Owner', label: 'Owner', category: 'data', description: 'The object this behavior is parented to.', inputs: [], outputs: [obj('object')], params: [], run: (ctx) => ({ outputs: { object: ctx.owner } }) });
+registerNode({
+  type: 'Parent',
+  label: 'Parent',
+  category: 'data',
+  description: 'The parent of an object (none for top-level objects).',
+  inputs: [obj('object')],
+  outputs: [obj('parent')],
+  params: [],
+  run: (_ctx, inputs) => ({ outputs: { parent: asEntity(inputs.object)?.parent ?? null } }),
+});
 registerNode({
   type: 'ObjectByName',
   label: 'Object by name',
@@ -141,13 +151,14 @@ registerNode({
   type: 'GetPosition',
   label: 'Get position',
   category: 'data',
-  description: 'The x/y position of an object.',
+  description: 'The position of an object: local to its parent (x/y) and in world units (world x/y).',
   inputs: [obj('object')],
-  outputs: [num('x'), num('y')],
+  outputs: [num('x'), num('y'), num('worldX', 'world x'), num('worldY', 'world y')],
   params: [],
   run: (_ctx, inputs) => {
     const target = asEntity(inputs.object);
-    return { outputs: { x: target?.x ?? 0, y: target?.y ?? 0 } };
+    const world = target ? worldPositionOf(target) : { x: 0, y: 0 };
+    return { outputs: { x: target?.x ?? 0, y: target?.y ?? 0, worldX: world.x, worldY: world.y } };
   },
 });