一图胜千言, 图中有一条路径path, 沿着路径描了一条宽度为 width 的边, miterLimit 代表的是, 比例 ab/ac, 其中ac的长度为 1/2 width
来看 mdn 上的描述, 进行验证
miterLimit = max miterLength / lineWidth = 1 / sin ( min θ / 2 )- The default miter limit of 10.0 will strip all miters for sharp angles below about 11 degrees.
- A miter limit equal to √2 ≈ 1.4142136 (rounded up) will strip miters for all acute angles, keeping miter joins only for obtuse or right angles.
- A miter limit equal to 1.0 is valid but will disable all miters.
- Values below 1.0 are invalid for the miter limit.
一张图告诉你 canvas 中的 miterLimit 代表着什么
原文：http://www.cnblogs.com/linyuzhaozhao/p/7096907.html
