Render error bars for the set of points

Usage no npm install needed!

<script type="module">
  import reglError2d from '';


regl-error2d experimental

Draw error bars for a set of points with regl.


Remake on gl-error2d:

  • color may define per-bar colors.
  • max number of points extended 40 times (from 1e5 to 4e6) via instanced draw.
  • lineWidth and capSize are adjusted to actual pixels.
  • enhanced performance via vertex shader.



npm install regl-error2d

let regl = require('regl')({extensions: 'angle_instanced_arrays'})
let createError2d = require('regl-error2d')

let error2d = createError2d(regl)

  positions: [0,0, .5,0, ...],
  errors: [.5,.5,.5,.6, .2,.3,.4,.1, ...],
  color: 'rgba(0, 100, 200, .75)'

createError2d(regl, options?)

Create new error2d instance from regl and initial options. Note that regl instance should have ANGLE_instanced_arrays extension enabled.


Draw errors, update options.

Option Default Description
positions, points, data [] An array of unrolled xy coordinates of the points as [x,y, x,y, ...] or array of points [[x,y], [x,y], ...].
errors, error [] Array with error values corresponding to the points [e0l,e0r,e0b,e0t, e1l,e1r,e1b,e1t, ...]
capSize, cap 5 Error bar cap size, in pixels
lineWidth, thickness 1 Error bar line width, in pixels
color, colors 'red' Color or array with colors. Each color can be a css color string or an array with float 0..1 values.
opacity 1 Error bars opacity.
range, dataBox null Visible data range.
viewport, viewBox null Output area within the canvas.

A list of options can be passed for batch rendering:

error2d([options1, options2, ...])


Update options, not incurring redraw.


Draw errors based on last options. id integer can specify a list item to redraw from batch update.


Dispose error2d and associated resources.


(c) 2017 Dima Yv. MIT License

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