/// <summary>
/// 3点圆计算标准圆
/// </summary>
/// <param name="FP3"></param>
/// <returns></returns>
public static CircleNorm GetCircle(CircleFP3 FP3)
{
CircleNorm cirN = new CircleNorm();
cirN.Center.X = (float)(((FP3.p2.Y - FP3.p1.Y) * (FP3.p3.Y * FP3.p3.Y - FP3.p1.Y * FP3.p1.Y + FP3.p3.X * FP3.p3.X - FP3.p1.X * FP3.p1.X) - (FP3.p3.Y - FP3.p1.Y) * (FP3.p2.Y * FP3.p2.Y - FP3.p1.Y * FP3.p1.Y + FP3.p2.X * FP3.p2.X - FP3.p1.X * FP3.p1.X)) / (2.0 * ((FP3.p3.X - FP3.p1.X) * (FP3.p2.Y - FP3.p1.Y) - (FP3.p2.X - FP3.p1.X) * (FP3.p3.Y - FP3.p1.Y))));
cirN.Center.Y = (float)(((FP3.p2.X - FP3.p1.X) * (FP3.p3.X * FP3.p3.X - FP3.p1.X * FP3.p1.X + FP3.p3.Y * FP3.p3.Y - FP3.p1.Y * FP3.p1.Y) - (FP3.p3.X - FP3.p1.X) * (FP3.p2.X * FP3.p2.X - FP3.p1.X * FP3.p1.X + FP3.p2.Y * FP3.p2.Y - FP3.p1.Y * FP3.p1.Y)) / (2.0 * ((FP3.p3.Y - FP3.p1.Y) * (FP3.p2.X - FP3.p1.X) - (FP3.p2.Y - FP3.p1.Y) * (FP3.p3.X - FP3.p1.X))));
cirN.Radius = (float)System.Math.Sqrt((FP3.p1.X - cirN.Center.X) * (FP3.p1.X - cirN.Center.X) + (FP3.p1.Y - cirN.Center.Y) * (FP3.p1.Y - cirN.Center.Y));
return(cirN);
}
/// <summary>
/// 判断任意点是否在标准圆内
/// </summary>
/// <param name="p">任意点</param>
/// <param name="CirNorm">标准圆</param>
/// <returns>true：在圆内 false：在圆外</returns>
public static bool Contains(FPointXY p, CircleNorm CirNorm)
{
if ((CirNorm.Center.X - p.X) * (CirNorm.Center.X - p.X) + (CirNorm.Center.Y - p.Y) * (CirNorm.Center.Y - p.Y) < CirNorm.Radius * CirNorm.Radius)
{
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// 求标准圆上任意X对应的Y
/// </summary>
/// <param name="CirN">已知标准圆</param>
/// <param name="X">圆上任意X坐标</param>
/// <param name="symbol">符号，true：取大值，false：取小指</param>
/// <returns>对应的Y</returns>
public static float GetCircleY(CircleNorm CirN, float X, bool Symbol)
{
int symbol;
if (Symbol)
{
symbol = 1;
}
else
{
symbol = -1;
}
return((float)(CirN.Center.Y + symbol * System.Math.Sqrt(CirN.Radius * CirN.Radius - (CirN.Center.X - X) * (CirN.Center.X - X))));
}
/// <summary>
/// 求3点圆上任意Y对应的X
/// </summary>
/// <param name="CirFP3">已知3点圆</param>
/// <param name="Y">圆上任意X坐标</param>
/// <param name="symbol">符号，true：取大值，false：取小指</param>
/// <returns>对应的X</returns>
public static float GetCircleX(CircleFP3 CirFP3, float Y, bool Symbol)
{
int symbol;
CircleNorm CirN = GetCircle(CirFP3);
if (Symbol)
{
symbol = 1;
}
else
{
symbol = -1;
}
return((float)(CirN.Center.X + symbol * System.Math.Sqrt(CirN.Radius * CirN.Radius - (CirN.Center.Y - Y) * (CirN.Center.Y - Y))));
}