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GroupNode

GroupNode extends ScenegraphNode with child-node management and traversal helpers.

Usage​

import {GroupNode} from '@luma.gl/engine';

const group = new GroupNode();
group.add(childNodeA, childNodeB);

Types​

GroupNodeProps​

export type GroupNodeProps = ScenegraphNodeProps & {
  children?: ScenegraphNode[];
};

export type DepthSortedTraversalOptions = {
  viewMatrix: NumericArray;
  worldMatrix?: NumericArray;
  order?: 'back-to-front' | 'front-to-back';
};

export type DepthSortedTraversalContext = {
  worldMatrix: Matrix4;
  bounds: [number[], number[]] | null;
  depth: number;
};

Properties​

children​

The current list of child nodes.

Methods​

constructor(children: ScenegraphNode[])​

Creates a group from an initial child list.

constructor(props?: GroupNodeProps)​

Creates a group from node props plus optional children.

getBounds(): [number[], number[]] | null​

Returns world-space bounds aggregated from all descendants that provide bounds, including nested group transforms, leaf transforms, and every transformed bounding-box corner.

destroy(): void​

Destroys all children and clears the child list.

add(...children): this​

Adds one or more children. Nested arrays are unpacked recursively.

remove(child: ScenegraphNode): this​

Removes one child.

removeAll(): this​

Clears all children.

traverse(visitor, {worldMatrix} = {})​

Traverses descendants depth-first and calls the visitor for non-group leaf nodes.

traverseDepthSorted(visitor, options)​

Flattens leaf descendants and visits them in camera-depth order using their aggregate bounding-box centers. The default order is back-to-front; set order: 'front-to-back' for opaque rendering or other front-first workflows.

group.traverseDepthSorted(
  (node, {worldMatrix, bounds, depth}) => {
    if (node instanceof ModelNode) {
      node.draw(renderPass);
    }
  },
  {viewMatrix, order: 'back-to-front'}
);

The visitor's worldMatrix includes both ancestor transforms and the leaf node transform. Sorting is stable for equal depths and preserves instanced models as a single visited node and draw.

preorderTraversal(visitor, {worldMatrix} = {})​

Traverses the group and its descendants in preorder, including the group itself.