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gl-plot2d

A rendering engine for drawing huge 2D plots using WebGL.

Install

With npm,

npm i gl-plot2d

API

Constructor

var plot = require('gl-plot2d')(options)

Constructs a new gl-plot2d object.

  • options is an object containing parameters for constructing the plot

Options can contain the following parameters,

Required properties
Property Description
gl A WebGLRenderingContext object, into which the plot is drawn
pixelRatio A scale factor which is applied to pixel coordinates
screenBox Bounds on the plot within the WebGL context
viewBox Pixel coordinates where the plot is drawn
dataBox Data coordinates for the view of the plot

Note: Coordinates for screenBox, viewBox, dataBox, etc. are given by 4-tuples of bounding box coordinates in the form [xmin, ymin, xmax, ymax].

Border and background colors
Property Description Default
borderColor Border color as a normalized RGBA tuple [0,0,0,0]
backgroundColor Background color [0,0,0,0]
borderLineEnable Toggle drawing lines for left,bottom,right,top of border [true,true,true,true]
borderLineWidth Width of border lines [2,2,2,2]
borderLineColor Color of border lines [[0,0,0,1], [0,0,0,1], [0,0,0,1], [0,0,0,1]]

Note: For properties which are specified per-screen direction like borderLineEnable etc., the components are always arranged in the order left,bottom,right,top.

Ticks
Property Description Default
ticks See note below [[], []]
tickEnable Turn on display of ticks for a given axis [true, true, true, true]
tickPad Distance between tick text and tick marks [15,15,15,15]
tickAngle Angle to draw ticks at [0,0,0,0]
tickColor Color of tick labels [[0,0,0,1], [0,0,0,1], [0,0,0,1], [0,0,0,1]]
tickMarkWidth Tick marks [0,0,0,0]
tickMarkLength [0,0,0,0]
tickMarkColor [[0,0,0,1],[0,0,0,1],[0,0,0,1],[0,0,0,1]]

Note: Ticks are encoded as an array of objects, each with the following properties:

  • x The data coordinate of the tick
  • text The text associated to the tict mark
  • font The font for the text
  • size The font size for the tick
Labels
Property Description Default
labels The label text for each axis ['x', 'y']
labelEnable Turns on/off rendering for the labels on the left,bottom,top,right [true, true, true, true]
labelAngle Angle to draw label text [0,Math.PI/2,0,3.0*Math.PI/2]
labelPad Padding for labels in pixel coordinates [15,15,15,15]
labelSize Size of labels in pixels [12, 12]
labelFont Font for labels ['sans-serif', 'sans-serif']
labelColor Color of labels [[0,0,0,1],[0,0,0,1],[0,0,0,1],[0,0,0,1]]
Title
Property Description Default
title Title text ''
titleEnable Toggles title rendering true
titleCenter Pixel coordinates for center of title [0.5*(viewBox[0]+viewBox[2]), viewBox[3] - 40]
titleAngle Angle to draw title text 0
titleColor Color of title [0,0,0,1]
titleFont Title font 'sans-serif'
titleSize Title font size 18
Grid lines
Property Description Default
gridLineEnable Turns on grid lines per axis [true, true]
gridLineColor Grid line color [[0,0,0,0.5], [0,0,0,0.5]]
gridLineWidth Width of grid lines [1, 1]
zeroLineEnable Toggle rendering of zero line [true, true]
zeroLineWidth Width of zero line in pixels [2, 2]
zeroLineColor Color of zero line [[0,0,0,1], [0,0,0,1]]

Methods

plot.update(options)

Updates the properties of the plot.

  • options is an option structure, as described in the constructor

plot.draw()

Redraws the plot. Call this once per requestAnimationFrame()

plot.pick(x, y)

Finds the current data point highlighted by the user.

  • x,y are the coordinates of the mouse in pixel coordinates

Returns If the user is selecting a data point, then returns the current data point selected by the user. Otherwise, returns null

plot.dispose()

Destroy plot and release all associated resources

License

(c) Mikola Lysenko. MIT License

Supported by plot.ly