Generates a spline's polyline from inline WGSL you write — the way to describe a curve as a per-vertex formula (a parametric knot, a rose curve, a live time-varying shape) and have the GPU evaluate it every frame.

Declarative element: <sk-custom-wgsl-spline-source>

Not on the sk.* global — construct via the declarative element or a module import.

Remarks

This is the WGSL-authored member of the spline-source family: a spline-source supplies the curve geometry for a AbstractSpline, so it lives as the single geometry child of a sk-spline. You write only fn getSplineVertex(index: u32) -> SplineVertex; the source runs its own generation dispatch (one GPU thread per vertex, engine-owned fn main) into a polyline the renderer consumes through the shared zero-copy + readback path. A kernel that reads params.time (scene time in milliseconds) re-generates every frame; a static kernel dispatches once per change. CPU-side queries (pointAt, bounds, cloner matrices) come from the readback path and are null until the first readback — as with sk-compute-buffer-spline-source.

Key attributes. vertex-count is how many polyline vertices to generate — getSplineVertex is called once per index 0 … vertex-count-1. wgsl is the inline kernel body; src loads the WGSL from an external file instead (and, like <script src>, wins over inline wgsl), with on-load / on-error handlers for the fetch. is-closed declares the generated polyline a closed loop. Author parameters are `sk-wgsl-uniform children (and the vec/array variants), read inside the kernel via the generated skUniform_<name>() accessors; changing a uniform value re-uploads and re-dispatches without a pipeline rebuild. Like every spline-source it also carries the family's distribution / distribution-count` controls: a spline-source is itself a points-source, so a sk-cloner given one places clones along the curve, and these controls choose how it is sampled into those positions.

Related. It is one input modality of the spline-source family alongside sk-svg-spline-source, sk-points-spline-source, sk-trail-spline-source, sk-morph-spline-source, and its GPU sibling sk-compute-buffer-spline-source (which reads a separate sk-compute-node producer rather than owning the kernel). It parameterizes the kernel with sk-wgsl-uniform children; its host is a sk-spline, whose curve then draws with a stroke paint or carries an sk-align-to-spline-constraint.

Constructor

constructor(config?: { vertexCount: number; wgsl?: string; src?: string; isClosed?: boolean })

Inherited from: GPUPolylineSplineSource, SkenraAnimatable — see those pages for inherited members.

Properties

Config Properties

Property	Type	Default	Description	Declared by
vertexCount	number	1	Number of polyline vertices to generate. Setting it is structural	CustomWGSLSplineSource
wgsl	string	""	Inline WGSL vertex function. Ignored while src is set.	CustomWGSLSplineSource
src	string	—	External WGSL source URL (the src attribute), or null if none.	CustomWGSLSplineSource
isClosedanimatable	boolean	false	Whether the spline forms a closed loop (last vertex joins the first).	GPUPolylineSplineSource

Other Properties

Property	Type	Default	Description	Declared by
configuredVertexCountread-only	number	—	The configured vertex count, independent of the inert state (for	CustomWGSLSplineSource
hasEffectiveWGSLread-only	boolean	—	Whether usable effective WGSL is available. false while a src is	CustomWGSLSplineSource
pointCountread-only	number	—	Cloner-facing point count. Tracks distribution; for a GPU source	GPUPolylineSplineSource
localMatricesread-only	Float32Array<ArrayBufferLike> | null	—	Per-vertex [ T·width | N·width | B·width | P ] frame matrices, or null until data is available.	GPUPolylineSplineSource
distributionanimatable	SplineDistributionMode	—	How clone points are placed along the spline — at the control points, at	GPUPolylineSplineSource
distributionCount	number	—	The number of evenly spaced points to place when the distribution is	GPUPolylineSplineSource
isValidread-only	boolean	—	Whether the source initialized successfully and holds at least one vertex.	GPUPolylineSplineSource
polylineread-only	readonly Readonly<SplinePoint>[]	[]	Read-only view of the internal 3D polyline points.	GPUPolylineSplineSource
sceneread-only	any	—	Gets the Scene this animatable belongs to, if any.	SkenraAnimatable
animationsread-only	SkenraAnimation[]	—	Public getter for the animations affecting this target.	SkenraAnimatable

Methods

Method	Description	Declared by
addUniform(name: string, value: number): WGSLUniform	Imperative twin of authoring a <sk-wgsl-uniform> child.	CustomWGSLSplineSource
addF32ArrayUniform(name: string, values: readonly number[]): WGSLF32ArrayUniform	Imperative twin of authoring a <sk-wgsl-f32-array-uniform> child.	CustomWGSLSplineSource
addVec2Uniform(name: string, x: number, y: number): WGSLVec2Uniform	Imperative twin of authoring a <sk-wgsl-vec2-uniform> child.	CustomWGSLSplineSource
addVec3Uniform(name: string, x: number, y: number, z: number): WGSLVec3Uniform	Imperative twin of authoring a <sk-wgsl-vec3-uniform> child.	CustomWGSLSplineSource
addVec4Uniform(name: string, x: number, y: number, z: number, w: number): WGSLVec4Uniform	Imperative twin of authoring a <sk-wgsl-vec4-uniform> child.	CustomWGSLSplineSource
addColorUniform(name: string, color: ColorInput): WGSLColorUniform	Imperative twin of authoring a <sk-wgsl-color-uniform> child.	CustomWGSLSplineSource
pointAt(t: number): SplinePoint | null	Returns a point on the spline at normalized parameter t.	GPUPolylineSplineSource
getBoundsInSpace(fullTransform: Float32Array): PolylineBounds | null	Axis-aligned bounding box of the produced points, expressed in the given target space, or null if there is no data yet.	GPUPolylineSplineSource
animate(firstArg: TypedKeyframe<this>[] | TypedPropertyIndexedKeyframes<this> | Record<string, any> | globalThis.Keyframe[] | globalThis.PropertyIndexedKeyframes | null, secondArg?: number | KeyframeAnimationOptions | globalThis.KeyframeAnimationOptions): SkenraAnimation & Animation	Creates a new SkenraAnimation for this target per Web Animations API.	SkenraAnimatable
removeAnimation(animation: SkenraAnimation): boolean	Removes a specific animation from this object.	SkenraAnimatable
constrain(type: K, config: ConstraintConfigMap[K]): ConstraintReturnMap[K]	Creates a constraint on this Animatable using a fluent API.	SkenraAnimatable

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