Primitive

Primitives are individual GPU draw calls comprising a Mesh.

Meshes typically have only a single Primitive, although various cases may require more. Each primitive may be assigned vertex attributes, morph target attributes, and a material. Any of these properties should be reused among multiple primitives where feasible.

Primitives cannot be moved independently of other primitives within the same mesh, except through the use of morph targets and skinning. If independent movement or other runtime behavior is necessary (like raycasting or collisions) prefer to assign each primitive to a different mesh. The number of GPU draw calls is typically not affected by grouping or ungrouping primitives to a mesh.

Each primitive may optionally be deformed by one or more morph targets, stored in a PrimitiveTarget.

Usage:

const primitive = doc.createPrimitive()
    .setAttribute('POSITION', positionAccessor)
    .setAttribute('TEXCOORD_0', uvAccessor)
    .setMaterial(material);
mesh.addPrimitive(primitive);
node.setMesh(mesh);

References:

Hierarchy

Static properties

Mode: Record<string, GLTF.MeshPrimitiveMode>

Type of primitives to render. All valid values correspond to WebGL enums.

Properties

propertyType: PropertyType.PRIMITIVE

Methods

  • getAttribute(semantic: string): Accessor
  • listAttributes(): Accessor[]

  • Lists all vertex attribute Accessors associated with the primitive, excluding any attributes used for morph targets. For example, [positionAccessor, normalAccessor, uvAccessor]. Order will be consistent with the order returned by {@link .listSemantics}().

  • dispatchEvent(event: BaseEvent): this

  • Dispatches an event on the GraphNode, and on the associated Graph. Event types on the graph are prefixed, "node:[type]".

  • dispose(): void

  • Removes both inbound references to and outbound references from this object. At the end of the process the object holds no references, and nothing holds references to it. A disposed object is not reusable.

  • equals(other: Property, skip?: Set<string>): boolean

  • Returns true if two properties are deeply equivalent, recursively comparing the attributes of the properties. Optionally, a 'skip' set may be included, specifying attributes whose values should not be considered in the comparison.

    Example: Two Primitives are equivalent if they have accessors and materials with equivalent content — but not necessarily the same specific accessors and materials.

  • addEventListener(type: string, listener: EventListener<T>): this
  • removeEventListener(type: string, listener: EventListener<T>): this
  • getExtension(name: string): Prop | null
  • listExtensions(): ExtensionProperty[]
  • getExtras(): Record<string, unknown>

  • Returns a reference to the Extras object, containing application-specific data for this Property. Extras should be an Object, not a primitive value, for best portability.

  • setExtras(extras: Record<string, unknown>): Property

  • Updates the Extras object, containing application-specific data for this Property. Extras should be an Object, not a primitive value, for best portability.

  • isDisposed(): boolean

  • Returns true if the node has been permanently removed from the graph.

  • getMode(): GLTF.MeshPrimitiveMode
  • setMode(mode: GLTF.MeshPrimitiveMode): Primitive
  • getName(): string

  • Returns the name of this property. While names are not required to be unique, this is encouraged, and non-unique names will be overwritten in some tools. For custom data about a property, prefer to use Extras.

  • Sets the name of this property. While names are not required to be unique, this is encouraged, and non-unique names will be overwritten in some tools. For custom data about a property, prefer to use Extras.

  • listParents(): Property[]

  • Returns a list of all properties that hold a reference to this property. For example, a material may hold references to various textures, but a texture does not hold references to the materials that use it.

    It is often necessary to filter the results for a particular type: some resources, like Accessors, may be referenced by different types of properties. Most properties include the Root as a parent, which is usually not of interest.

    Usage:

    const materials = texture
    .listParents()
    .filter((p) => p instanceof Material)
  • listSemantics(): string[]

  • Lists all vertex attribute semantics associated with the primitive, excluding any semantics used for morph targets. For example, ['POSITION', 'NORMAL', 'TEXCOORD_0']. Order will be consistent with the order returned by {@link .listAttributes}().

  • listTargets(): PrimitiveTarget[]
Function symbol, where the argument and output are a box labeled 'glTF'.

Made by Don McCurdy. Documentation built with greendoc and published under Creative Commons Attribution 3.0.