/// <summary>
/// 三角形面积
/// </summary>
/// <param name="p1"></param>
/// <param name="p2"></param>
/// <param name="p3"></param>
/// <returns></returns>
public static float GetTriangleArea(Vector2 p1, Vector2 p2, Vector2 p3)
{
float[] value =
{
1, p1.x, p1.y,
1, p2.x, p2.y,
1, p3.x, p2.y
};
var det = new Detaminate(value, 3);
return(0.5f * Mathf.Abs(det.Sum));
}
/// <summary>
/// 在平面上，获取点与线的位置关系
/// 返回结果：-1左边，0线上，1右边
/// </summary>
/// <param name="point"></param>
/// <param name="src"></param>
/// <param name="dest"></param>
/// <returns>-1左边，0线上，1右边</returns>
public static int GetPointPosition(Vector2 point, Vector2 src, Vector2 dest)
{
float[] value =
{
1, src.x, src.y,
1, dest.x, dest.y,
1, point.x, point.y
};
var det = new Detaminate(value, 3);
if (det.Sum < 0)
{
return(1);
}
if (det.Sum > 0)
{
return(-1);
}
return(0);
}
