Function isLeft

explainshell/web/static/js/d3.v3.js:2691–2693

(a, b, c)

        return wn !== 0;
      }
      function isLeft(a, b, c) {
        return (b[0] - a[0]) * (c[1] - a[1]) - (c[0] - a[0]) * (b[1] - a[1]);
      }
      function interpolate(from, to, direction, listener) {
        var a = 0, a1 = 0;
        if (from == null || (a = corner(from, direction)) !== (a1 = corner(to, direction)) || comparePoints(from, to) < 0 ^ direction > 0) {