/**
 * NURBS curves and surfaces, and polyline ("Line") geometry.
 *
 * The basis evaluation and tessellation follow the FBX SDK conventions as implemented by ufbx: knot spans are
 * subdivided uniformly, closed and periodic curves wrap their control points, and surfaces are tessellated into
 * quads (degenerate quads at poles become triangles) with welded positions along the wrapped edges.
 */
import { type FBXNode } from "../types/fbxTypes.js";
import { type FBXGeometryData, type FBXGeometryDiagnostic } from "./geometry.js";
export type FBXNurbsTopology = "open" | "closed" | "periodic";
/** Knot vector and derived data of one parametric direction. */
export interface FBXNurbsBasis {
    order: number;
    topology: FBXNurbsTopology;
    knots: Float64Array;
    /** Parameter range that the curve is defined on */
    tMin: number;
    tMax: number;
    /** Distinct knot values inside [tMin, tMax], i.e. the boundaries of the non-empty spans */
    spans: Float64Array;
    /** False when the knot vector is too short or not monotonic */
    valid: boolean;
}
/** NURBS curve: homogeneous control points (x, y, z, w) and a basis. */
export interface FBXNurbsCurveData {
    basis: FBXNurbsBasis;
    /** Control points as x,y,z,w */
    controlPoints: Float64Array;
    numControlPoints: number;
}
/** NURBS surface: control points laid out as `v * numU + u`. */
export interface FBXNurbsSurfaceData {
    basisU: FBXNurbsBasis;
    basisV: FBXNurbsBasis;
    numU: number;
    numV: number;
    /** Control points as x,y,z,w */
    controlPoints: Float64Array;
    flipNormals: boolean;
    /** Span subdivision stored in the file (Step), 0 when absent */
    stepU: number;
    stepV: number;
}
/** Polyline geometry ready for a lines mesh: one or more open or closed point runs. */
export interface FBXCurveGeometryData {
    id: number;
    name: string;
    kind: "line" | "nurbsCurve";
    /** Each polyline as x,y,z triples; closed runs repeat their first point at the end */
    polylines: Float64Array[];
    /** Display colour from the geometry's Color property */
    color: [number, number, number] | null;
    diagnostics: FBXGeometryDiagnostic[];
}
export declare function createNurbsBasis(order: number, form: string | undefined, knots: Float64Array): FBXNurbsBasis;
/**
 * Evaluates the basis functions (and their derivatives) that are non-zero at `u`.
 * @returns index of the first influencing control point, or -1 when the basis cannot be evaluated
 */
export declare function evaluateNurbsBasis(basis: FBXNurbsBasis, u: number, weights: Float64Array, derivatives: Float64Array | null): number;
/** Evaluates a curve point; `out` receives position (0..2) and derivative (3..5). */
export declare function evaluateNurbsCurve(curve: FBXNurbsCurveData, u: number, out: Float64Array, weights: Float64Array, derivs: Float64Array): boolean;
/** Evaluates a surface point; `out` receives position (0..2), du (3..5) and dv (6..8). */
export declare function evaluateNurbsSurface(surface: FBXNurbsSurfaceData, u: number, v: number, out: Float64Array, scratch: {
    wu: Float64Array;
    wv: Float64Array;
    du: Float64Array;
    dv: Float64Array;
}): boolean;
/**
 * Tessellates a curve into a polyline with `subdivision` segments per knot span. Closed and periodic curves
 * end on a copy of their first point.
 */
export declare function tessellateNurbsCurve(curve: FBXNurbsCurveData, subdivision?: number): Float64Array | null;
/** Span subdivision to use for a surface direction: an explicit override, else the file's Step, else 4. */
export declare function resolveSpanSubdivision(fileStep: number, override: number | undefined): number;
/**
 * Tessellates a surface into triangles. Positions on wrapped (closed/periodic) edges and at poles are welded
 * exactly like the FBX SDK does, so degenerate quads collapse into triangles.
 */
export declare function tessellateNurbsSurface(surface: FBXNurbsSurfaceData, subU: number, subV: number): {
    positions: Float64Array;
    indices: Uint32Array;
    normals: Float64Array;
    uvs: Float64Array;
} | null;
/** Reads a NurbsCurve geometry node. */
export declare function extractNurbsCurve(node: FBXNode): FBXNurbsCurveData | null;
/** Reads a NurbsSurface geometry node. */
export declare function extractNurbsSurface(node: FBXNode): FBXNurbsSurfaceData | null;
/** Tessellates a NurbsSurface geometry node into mesh geometry. */
export declare function nurbsSurfaceToGeometry(node: FBXNode, geometryId: number, subdivisionOverride: number | undefined): FBXGeometryData | null;
/** Reads a NurbsCurve geometry node into a tessellated polyline. */
export declare function extractNurbsCurveGeometry(node: FBXNode, geometryId: number, subdivision?: number): FBXCurveGeometryData;
/**
 * Reads a Line geometry node: Points plus PointsIndex where a negative index (~index) ends a segment, as in
 * polygon vertex indices.
 */
export declare function extractLineGeometry(node: FBXNode, geometryId: number): FBXCurveGeometryData;