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webgl-to-img-stream npm version Build Status

Convert a WebGL context's canvas' pixel data into an image, and write that image to a writable stream. Meant to be used in Node.js

Background / Initial Motivation

This module is meant to help with testing WebGL components.

Say you have a WebGL component that takes your canvas' WebGL context and a model view matrix and draws a fire particle effect at a location of your choice. You can verify that that works by rendering it in node (using something like require('gl')) and then writing your rendering to a .png file on your file system using webgl-to-img-stream. You can then use something like image-diff to make sure that your new .png file matches the one that you expect.

To Install

$ npm install --save webgl-to-img-stream


var webGlToImgStream = require('webgl-to-img-stream')
var fs = require('fs')
var canvasWidth = 128
var canvasHeight = 128
var gl = require('gl')(canvasWidth, canvasHeight)
// ... do whatever you want with your WebGL context ... 
var outputFile = fs.createWriteStream('./image.png')
webGlToImgStream(gl, canvasWidth, canvasHeight, outputFile)
// Your canvas's contents have now been saved to your file system 

See Also