/// <summary>
/// 获得外接圆的包围盒
/// </summary>
/// <param name="circle"></param>
/// <returns></returns>
public static Rect GetCircleBoundBox(Circle circle)
{
Rect bBox = new Rect();
bBox.xMin = circle.center.x - circle.radius;
bBox.xMax = circle.center.x + circle.radius;
bBox.yMin = circle.center.y - circle.radius;
bBox.yMax = circle.center.y + circle.radius;
return bBox;
}
/// <summary>
/// Checks the cross.
/// </summary>
/// <returns><c>true</c>, if cross was checked, <c>false</c> otherwise.</returns>
/// <param name="line">Line.</param>
/// <param name="cir">Cir.</param>
public static bool CheckCross( Line2D line , Circle cir )
{
return CheckCross(line , cir.center , cir.radius);
}
/// <summary>
/// Calculate the circle tangency.
/// </summary>
/// <returns>The circle tangency.</returns>
/// <param name="c">C.</param>
/// <param name="st">St.</param>
public static Vector2[] CalCircleTangency( Circle c , Vector2 st )
{
Vector2 dir;
float dis = (c.center - st).magnitude;
float temp= Mathf.Sqrt(dis*dis-c.radius*c.radius);
float sina=temp/dis;
float cosa=c.radius/dis;
dir.x=(st.x-c.center.x)/dis*c.radius;
dir.y=(st.y-c.center.y)/dis*c.radius;
Vector2[] res = new Vector2[2];
res[0].x = c.center.x+(dir.x*cosa-dir.y*sina);
res[0].y = c.center.y+(dir.x*sina+dir.y*cosa);
res[1].x = c.center.x+(dir.x*cosa+dir.y*sina);
res[1].y = c.center.y+(-dir.x*sina+dir.y*cosa);
return res;
}