https://mattdesl.svbtle.com/drawing-lines-is-hard
http://perfectionkills.com/exploring-canvas-drawing-techniques/



https://github.com/mattdesl/polyline-normals

var path = [ [0, 122], [0, 190], [90, 190] ]

//get the normals as a closed loop
var normals = getNormals(path, true)