AreaPlot

AreaPlot (from scenerystack/bamboo) combines the look of a LinePlot with the shading of a BarPlot: it renders a (Vector2 | null)[] dataset as a filled region bounded above by the line through the data and below by a horizontal baseline value. It extends scenerystack/scenery's Path, rebuilding its Shape whenever the dataset, baseline, or the chart transform changes. As with LinePlot, a null entry in the dataset closes off the current shaded region and starts a new one on the next non-null point, rather than plotting a point at the origin.

import { ChartTransform, AreaPlot } from 'scenerystack/bamboo';
import { Range, Vector2 } from 'scenerystack/dot';

A minimal example

const chartTransform = new ChartTransform( {
  viewWidth: 400,
  viewHeight: 200,
  modelXRange: new Range( 0, 10 ),
  modelYRange: new Range( -1, 1 )
} );

const dataSet: ( Vector2 | null )[] = [];
for ( let x = 0; x <= 10; x += 0.1 ) {
  dataSet.push( new Vector2( x, Math.sin( x ) ) );
}

const areaPlot = new AreaPlot( chartTransform, dataSet, {
  baseline: 0,
  fill: 'rgba(0,100,255,0.4)'
} );

Constructor

new AreaPlot( chartTransform: ChartTransform, dataSet: ( Vector2 | null )[], providedOptions?: AreaChartOptions )

Options

Option	Default	Effect
baseline	0	The y-value (in model coordinates) that forms the foundation of the shaded region — each shaded run of points is closed by dropping straight down to this value at its first and last x
fill (inherited PathOptions)	'black'	Fill color of the shaded region

Methods

Member	Description
dataSet	(Vector2 | null)[] — public field. Safe to read directly; if you mutate it in place, you're responsible for calling update() yourself
baseline	number — public field, mirrors the baseline option. Same caveat as dataSet if mutated directly
setDataSet( dataSet )	Replaces the dataset and immediately calls update()
setBaseline( baseline )	Replaces the baseline and immediately calls update()
update()	Recomputes the shaded Shape from the current dataSet and baseline; called automatically on construction and whenever the ChartTransform's changedEmitter fires
dispose()	Removes the chartTransform.changedEmitter listener before calling Path.dispose()

Each run of non-null points closes independently at the baseline

AreaPlot walks the dataset and, on hitting a null (or the end of the array), draws a line straight down to baseline at the last point's x-coordinate and closes that subpath — then starts a fresh shaded region at the next non-null point. This is what makes null entries produce separate shaded islands rather than one continuous fill with a hole punched through the gap, and it's the same convention LinePlot uses for line segments, just with an extra close-to-baseline step.