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📄 NURBSCurve.js

📊 Analysis Summary

Metric Count
🔧 Functions 4
🧱 Classes 1
📦 Imports 3
📊 Variables & Constants 7

📚 Table of Contents

🛠️ File Location:

📂 examples/jsm/curves/NURBSCurve.js

📦 Imports

Name Source
Curve three
Vector3 three
Vector4 three

Variables & Constants

Name Type Kind Value Exported
knotsLength number let/var knots ? knots.length - 1 : 0 ✗
pointsLength number let/var controlPoints ? controlPoints.length : 0 ✗
point any let/var controlPoints[ i ] ✗
point Vector3 let/var optionalTarget ✗
u number let/var this.knots[ this.startKnot ] + t * ( this.knots[ this.endKnot ] - this.knots[... ✗
tangent Vector3 let/var optionalTarget ✗
u number let/var this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] ) ✗

Functions

NURBSCurve.getPoint(t: number, optionalTarget: Vector3): Vector3

JSDoc: 

/**
     * This method returns a vector in 3D space for the given interpolation factor.
     *
     * @param {number} t - A interpolation factor representing a position on the curve. Must be in the range `[0,1]`.
     * @param {Vector3} [optionalTarget] - The optional target vector the result is written to.
     * @return {Vector3} The position on the curve.
     */

Parameters:

  • t number
  • optionalTarget Vector3

Returns: Vector3

Calls:

  • NURBSUtils.calcBSplinePoint
  • hpoint.divideScalar
  • point.set

Internal Comments: 

// following results in (wx, wy, wz, w) homogeneous point (x2)
// project to 3D space: (wx, wy, wz, w) -> (x, y, z, 1) (x4)

Code 
getPoint( t, optionalTarget = new Vector3() ) {

        const point = optionalTarget;

        const u = this.knots[ this.startKnot ] + t * ( this.knots[ this.endKnot ] - this.knots[ this.startKnot ] ); // linear mapping t->u

        // following results in (wx, wy, wz, w) homogeneous point
        const hpoint = NURBSUtils.calcBSplinePoint( this.degree, this.knots, this.controlPoints, u );

        if ( hpoint.w !== 1.0 ) {

            // project to 3D space: (wx, wy, wz, w) -> (x, y, z, 1)
            hpoint.divideScalar( hpoint.w );

        }

        return point.set( hpoint.x, hpoint.y, hpoint.z );

    }

NURBSCurve.getTangent(t: number, optionalTarget: Vector3): Vector3

JSDoc: 

/**
     * Returns a unit vector tangent for the given interpolation factor.
     *
     * @param {number} t - The interpolation factor.
     * @param {Vector3} [optionalTarget] - The optional target vector the result is written to.
     * @return {Vector3} The tangent vector.
     */

Parameters:

  • t number
  • optionalTarget Vector3

Returns: Vector3

Calls:

  • NURBSUtils.calcNURBSDerivatives
  • tangent.copy( ders[ 1 ] ).normalize
Code 
getTangent( t, optionalTarget = new Vector3() ) {

        const tangent = optionalTarget;

        const u = this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] );
        const ders = NURBSUtils.calcNURBSDerivatives( this.degree, this.knots, this.controlPoints, u, 1 );
        tangent.copy( ders[ 1 ] ).normalize();

        return tangent;

    }

NURBSCurve.toJSON(): any

Returns: any

Calls:

  • super.toJSON
  • this.controlPoints.map
  • p.toArray
Code 
toJSON() {

        const data = super.toJSON();

        data.degree = this.degree;
        data.knots = [ ...this.knots ];
        data.controlPoints = this.controlPoints.map( p => p.toArray() );
        data.startKnot = this.startKnot;
        data.endKnot = this.endKnot;

        return data;

    }

NURBSCurve.fromJSON(json: any): this

Parameters:

  • json any

Returns: this

Calls:

  • super.fromJSON
  • json.controlPoints.map
Code 
fromJSON( json ) {

        super.fromJSON( json );

        this.degree = json.degree;
        this.knots = [ ...json.knots ];
        this.controlPoints = json.controlPoints.map( p => new Vector4( p[ 0 ], p[ 1 ], p[ 2 ], p[ 3 ] ) );
        this.startKnot = json.startKnot;
        this.endKnot = json.endKnot;

        return this;

    }

Classes

NURBSCurve

Class Code 
class NURBSCurve extends Curve {

    /**
     * Constructs a new NURBS curve.
     *
     * @param {number} degree - The NURBS degree.
     * @param {Array<number>} knots - The knots as a flat array of numbers.
     * @param {Array<Vector2|Vector3|Vector4>} controlPoints - An array holding control points.
     * @param {number} [startKnot] - Index of the start knot into the `knots` array.
     * @param {number} [endKnot] - Index of the end knot into the `knots` array.
     */
    constructor( degree, knots, controlPoints, startKnot, endKnot ) {

        super();

        const knotsLength = knots ? knots.length - 1 : 0;
        const pointsLength = controlPoints ? controlPoints.length : 0;

        /**
         * The NURBS degree.
         *
         * @type {number}
         */
        this.degree = degree;

        /**
         * The knots as a flat array of numbers.
         *
         * @type {Array<number>}
         */
        this.knots = knots;

        /**
         * An array of control points.
         *
         * @type {Array<Vector4>}
         */
        this.controlPoints = [];

        /**
         * Index of the start knot into the `knots` array.
         *
         * @type {number}
         */
        this.startKnot = startKnot || 0;

        /**
         * Index of the end knot into the `knots` array.
         *
         * @type {number}
         */
        this.endKnot = endKnot || knotsLength;

        for ( let i = 0; i < pointsLength; ++ i ) {

            // ensure Vector4 for control points
            const point = controlPoints[ i ];
            this.controlPoints[ i ] = new Vector4( point.x, point.y, point.z, point.w );

        }

    }

    /**
     * This method returns a vector in 3D space for the given interpolation factor.
     *
     * @param {number} t - A interpolation factor representing a position on the curve. Must be in the range `[0,1]`.
     * @param {Vector3} [optionalTarget] - The optional target vector the result is written to.
     * @return {Vector3} The position on the curve.
     */
    getPoint( t, optionalTarget = new Vector3() ) {

        const point = optionalTarget;

        const u = this.knots[ this.startKnot ] + t * ( this.knots[ this.endKnot ] - this.knots[ this.startKnot ] ); // linear mapping t->u

        // following results in (wx, wy, wz, w) homogeneous point
        const hpoint = NURBSUtils.calcBSplinePoint( this.degree, this.knots, this.controlPoints, u );

        if ( hpoint.w !== 1.0 ) {

            // project to 3D space: (wx, wy, wz, w) -> (x, y, z, 1)
            hpoint.divideScalar( hpoint.w );

        }

        return point.set( hpoint.x, hpoint.y, hpoint.z );

    }

    /**
     * Returns a unit vector tangent for the given interpolation factor.
     *
     * @param {number} t - The interpolation factor.
     * @param {Vector3} [optionalTarget] - The optional target vector the result is written to.
     * @return {Vector3} The tangent vector.
     */
    getTangent( t, optionalTarget = new Vector3() ) {

        const tangent = optionalTarget;

        const u = this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] );
        const ders = NURBSUtils.calcNURBSDerivatives( this.degree, this.knots, this.controlPoints, u, 1 );
        tangent.copy( ders[ 1 ] ).normalize();

        return tangent;

    }

    toJSON() {

        const data = super.toJSON();

        data.degree = this.degree;
        data.knots = [ ...this.knots ];
        data.controlPoints = this.controlPoints.map( p => p.toArray() );
        data.startKnot = this.startKnot;
        data.endKnot = this.endKnot;

        return data;

    }

    fromJSON( json ) {

        super.fromJSON( json );

        this.degree = json.degree;
        this.knots = [ ...json.knots ];
        this.controlPoints = json.controlPoints.map( p => new Vector4( p[ 0 ], p[ 1 ], p[ 2 ], p[ 3 ] ) );
        this.startKnot = json.startKnot;
        this.endKnot = json.endKnot;

        return this;

    }

}

Methods

getPoint(t: number, optionalTarget: Vector3): Vector3
Code 
getPoint( t, optionalTarget = new Vector3() ) {

        const point = optionalTarget;

        const u = this.knots[ this.startKnot ] + t * ( this.knots[ this.endKnot ] - this.knots[ this.startKnot ] ); // linear mapping t->u

        // following results in (wx, wy, wz, w) homogeneous point
        const hpoint = NURBSUtils.calcBSplinePoint( this.degree, this.knots, this.controlPoints, u );

        if ( hpoint.w !== 1.0 ) {

            // project to 3D space: (wx, wy, wz, w) -> (x, y, z, 1)
            hpoint.divideScalar( hpoint.w );

        }

        return point.set( hpoint.x, hpoint.y, hpoint.z );

    }
getTangent(t: number, optionalTarget: Vector3): Vector3
Code 
getTangent( t, optionalTarget = new Vector3() ) {

        const tangent = optionalTarget;

        const u = this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] );
        const ders = NURBSUtils.calcNURBSDerivatives( this.degree, this.knots, this.controlPoints, u, 1 );
        tangent.copy( ders[ 1 ] ).normalize();

        return tangent;

    }
toJSON(): any
Code 
toJSON() {

        const data = super.toJSON();

        data.degree = this.degree;
        data.knots = [ ...this.knots ];
        data.controlPoints = this.controlPoints.map( p => p.toArray() );
        data.startKnot = this.startKnot;
        data.endKnot = this.endKnot;

        return data;

    }
fromJSON(json: any): this
Code 
fromJSON( json ) {

        super.fromJSON( json );

        this.degree = json.degree;
        this.knots = [ ...json.knots ];
        this.controlPoints = json.controlPoints.map( p => new Vector4( p[ 0 ], p[ 1 ], p[ 2 ], p[ 3 ] ) );
        this.startKnot = json.startKnot;
        this.endKnot = json.endKnot;

        return this;

    }