在看zrender源码时，看到点在多边形内的判断代码，特意粘出来，参考下：

/**         * 多边形包含判断         * 采用 non-zero winding rule         */        function isInsidePolygon(points, x, y) {            var N = points.length;            var w = 0;            for (var i = 0, j = N - 1; i < N; i++) {                var x0 = points[j][0];                var y0 = points[j][1];                var x1 = points[i][0];                var y1 = points[i][1];                w += windingLine(x0, y0, x1, y1, x, y);                j = i;            }            return w !== 0;        }        function windingLine(x0, y0, x1, y1, x, y) {            if ((y > y0 && y > y1) || (y < y0 && y < y1)) {                return 0;            }            if (y1 == y0) {                return 0;            }            var dir = y1 < y0 ? 1 : -1;            var t = (y - y0) / (y1 - y0);            var x_ = t * (x1 - x0) + x0;            return x_ > x ? dir : 0;        }