of a curve via {@link Curve#getLengths}. To ensure * precision when using methods like {@link Curve#getSpacedPoints}, it is * recommended to increase the value of this property if the curve is very large. * * @type {number} * @default 200 */ this.arcLengthDivisions = 200; /** * Must be set to `true` if the curve parameters have changed. * * @type {boolean} * @default false */ this.needsUpdate = false; /** * An internal cache that holds precomputed curve length values. * * @private * @type {?Array} * @default null */ this.cacheArcLengths = null; } /** * This method returns a vector in 2D or 3D space (depending on the curve definition) * for the given interpolation factor. * * @abstract * @param {number} t - A interpolation factor representing a position on the curve. Must be in the range `[0,1]`. * @param {(Vector2|Vector3)} [optionalTarget] - The optional target vector the result is written to. * @return {(Vector2|Vector3)} The position on the curve. It can be a 2D or 3D vector depending on the curve definition. */ getPoint( /* t, optionalTarget */ ) { warn( 'Curve: .getPoint() not implemented.' ); } /** * This method returns a vector in 2D or 3D space (depending on the curve definition) * for the given interpolation factor. Unlike {@link Curve#getPoint}, this method honors the length * of the curve which equidistant samples. * * @param {number} u - A interpolation factor representing a position on the curve. Must be in the range `[0,1]`. * @param {(Vector2|Vector3)} [optionalTarget] - The optional target vector the result is written to. * @return {(Vector2|Vector3)} The position on the curve. It can be a 2D or 3D vector depending on the curve definition. */ getPointAt( u, optionalTarget ) { const t = this.getUtoTmapping( u ); return this.getPoint( t, optionalTarget ); } /** * This method samples the curve via {@link Curve#getPoint} and returns an array of points representing * the curve shape. * * @param {number} [divisions=5] - The number of divisions. * @return {Array<(Vector2|Vector3)>} An array holding the sampled curve values. The number of points is `divisions + 1`. */ getPoints( divisions = 5 ) { const points = []; for ( let d = 0; d <= divisions; d ++ ) { points.push( this.getPoint( d / divisions ) ); } return points; } // Get sequence of points using getPointAt( u ) /** * This method samples the curve via {@link Curve#getPointAt} and returns an array of points representing * the curve shape. Unlike {@link Curve#getPoints}, this method returns equi-spaced points across the entire * curve. * * @param {number} [divisions=5] - The number of divisions. * @return {Array<(Vector2|Vector3)>} An array holding the sampled curve values. The number of points is `divisions + 1`. */ getSpacedPoints( divisions = 5 ) { const points = []; for ( let d = 0; d <= divisions; d ++ ) { points.push( this.getPointAt( d / divisions ) ); } return points; } /** * Returns the total arc length of the curve. * * @return {number} The length of the curve. */ getLength() { const lengths = this.getLengths(); return lengths[ lengths.length - 1 ]; } /** * Returns an array of cumulative segment lengths of the curve. * * @param {number} [divisions=this.arcLengthDivisions] - The number of divisions. * @return {Array} An array holding the cumulative segment lengths. */ getLengths( divisions = this.arcLengthDivisions ) { if ( this.cacheArcLengths && ( this.cacheArcLengths.length === divisions + 1 ) && ! this.needsUpdate ) { return this.cacheArcLengths; } this.needsUpdate = false; const cache = []; let current, last = this.getPoint( 0 ); let sum = 0; cache.push( 0 ); for ( let p = 1; p <= divisions; p ++ ) { current = this.getPoint( p / divisions ); sum += current.distanceTo( last ); cache.push( sum ); last = current; } this.cacheArcLengths = cache; return cache; // { sums: cache, sum: sum }; Sum is in the last element. } /** * Update the cumulative segment distance cache. The method must be called * every time curve parameters are changed. If an updated curve is part of a * composed curve like {@link CurvePath}, this method must be called on the * composed curve, too. */ updateArcLengths() { this.needsUpdate = true; this.getLengths(); } /** * Given an interpolation factor in the range `[0,1]`, this method returns an updated * interpolation factor in the same range that can be ued to sample equidistant points * from a curve. * * @param {number} u - The interpolation factor. * @param {?number} distance - An optional distance on the curve. * @return {number} The updated interpolation factor. */ getUtoTmapping( u, distance = null ) { const arcLengths = this.get