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