MarchingSquaresJS算法JS版

## Optimized implementation of the [Marching Squares](http://users.polytech.unice.fr/~lingrand/MarchingCubes/algo.html) algorithm in Javascript  Computation times for 20 iterations: | | old | new | optimized | |------------|------|-----|-----| | time in ms | 3876 | 443 | 20 | | time in % | 873 | 100 | **4** | The optimized version is approximately 217 times faster than the "old version" and **24 times faster** than the "new version" implemented by [sakri](https://github.com/sakri). [ES2015](http://www.ecma-international.org/ecma-262/6.0/) [features](https://kangax.github.io/compat-table/es6/) like TypedArrays, const and local scoping are used to gain this speed up. Test it yourself with this online [benchmark / demo](http://htmlpreview.github.io/?https://github.com/mamrehn/MarchingSquaresJS/blob/master/marchingSquaresTest.html). ## Original README Marching squares outlines blobs of non-transparent pixels inside a bitmap. This is a straight forward port from this excellent implementation by Phill Spiess: http://devblog.phillipspiess.com/2010/02/23/better-know-an-algorithm-1-marching-squares/ This is a Javascript implementation designed to be used with Html5 Canvas. Check out the code in marchingSquaresTest.html for usage example. http://htmlpreview.github.io/?https://github.com/sakri/MarchingSquaresJS/blob/master/marchingSquaresTest.html Here's a few codepen demos using it: A visualization of the algo as it executes http://codepen.io/sakri/full/aIirl Text Edge Flare http://codepen.io/sakri/full/vIKJp Ghost text http://codepen.io/sakri/full/zbqti He-Man effect http://codepen.io/sakri/full/wsiLC Here's a demo that tackles "blobs with holes" as in getting the outline for characters such as "O" "8" "&" etc. http://codepen.io/sakri/pen/LCrDe If there is interest, I can include the required code in this repo (floodFill, basic threshold etc.) Have a good day!