点是否在线段两侧

//点是否在线段两侧
public static bool IsPointSideOfLine(Vector2 p, Vector2 a, Vector2 b)
{
    var ap = p - a;
    var ab = b - a;
    if (Vector2.Dot(ap, ab) < 0) //夹角为钝角, 大于90度时, cos值<0
        return true;

    var ba = -ab;
    var bp = p - b;
    if (Vector2.Dot(ba, bp) < 0)
        return true;

    return false;
}