Function sub

libs/echarts/echarts.simple.js:990–994

* 向量相减 * @param {Vector2} out * @param {Vector2} v1 * @param {Vector2} v2

(out, v1, v2)

 * @param {Vector2} v2
 */
function sub(out, v1, v2) {
    out[0] = v1[0] - v2[0];
    out[1] = v1[1] - v2[1];
    return out;
}

/**
 * 向量长度