Scenegraphs

The luma.gl engine provides a set of Scenegraph classes to organize Models into a hierarchy.

Note that these classes are used by the @luma.gl/gltf module, which can transform a glTF file into a luma.gl Scenegraph.

But Scenegraphs can also be created programmatically by applications.

Nodes And Materials

In luma.gl, scenegraph nodes and materials play different roles:

• ScenegraphNode and GroupNode describe hierarchy, traversal, and transforms.
• ModelNode connects a renderable Model to that hierarchy.
• Material is not itself a node. It is a reusable rendering resource that renderable nodes and models can reference.

This distinction is important:

• Nodes participate in parent/child relationships and transform propagation.
• Materials do not have transforms, parents, or children.
• Multiple ModelNodes can share the same Material, just as they can share geometry or textures.

That makes Material scenegraph-adjacent rather than scenegraph-structural:

• it belongs to the engine-side scene representation,
• it is commonly created alongside meshes and nodes when loading glTF,
• but it should be treated as referenced data, not as part of the node hierarchy itself.

For a more detailed discussion of what belongs in a material, see the Materials guide.

This maps well to luma.gl's binding ownership model:

• group 0 is typically model or draw-local engine state,
• group 2 is typically scene-shared state such as lighting or IBL,
• group 3 is material state that can be reused across many renderable nodes.