/// <summary>
/// 判断在一个椭圆内部能否看到一个点。
/// </summary>
/// <param name="pt">点。</param>
/// <param name="offset">椭圆的焦点。</param>
/// <param name="semiMajorAxis">椭圆的半长轴。</param>
/// <param name="eccentricity">椭圆的离心率。</param>
/// <param name="rotateAngle">椭圆的旋转角（弧度）（以焦点为中心，以 +X 轴为 0 弧度，从 +X 轴指向 +Y 轴的方向为正方向，焦点到近焦点连线相对于 +X 轴的角度）。</param>
/// <returns>布尔值，表示在一个椭圆内部能否看到一个点。</returns>
public static bool PointIsVisibleInEllipse(PointD pt, PointD offset, double semiMajorAxis, double eccentricity, double rotateAngle)
{
if (pt.IsNaNOrInfinity || offset.IsNaNOrInfinity || (InternalMethod.IsNaNOrInfinity(semiMajorAxis) || semiMajorAxis <= 0) || (InternalMethod.IsNaNOrInfinity(eccentricity) || eccentricity < 0 || eccentricity >= 1) || InternalMethod.IsNaNOrInfinity(rotateAngle))
{
return(false);
}
else
{
PointD _Offset = new PointD(offset.X - 2 * semiMajorAxis * eccentricity * Math.Cos(rotateAngle), offset.Y - 2 * semiMajorAxis * eccentricity * Math.Sin(rotateAngle));
double FocalDistSum = pt.DistanceFrom(offset) + pt.DistanceFrom(_Offset);
return(FocalDistSum < 2 * semiMajorAxis);
}
}
/// <summary>
/// 判断在一个矩形内部能否看到一个直线段的部分或全部。
/// </summary>
/// <param name="pt1">直线段的第一个端点。</param>
/// <param name="pt2">直线段的第二个端点。</param>
/// <param name="rect">矩形。</param>
/// <returns>布尔值，表示在一个矩形内部能否看到一个直线段的部分或全部。</returns>
public static bool LineIsVisibleInRectangle(PointD pt1, PointD pt2, RectangleF rect)
{
if (pt1.IsNaNOrInfinity || pt2.IsNaNOrInfinity || rect.Size.IsEmpty)
{
return(false);
}
else
{
PointD RectCenter = new PointD(rect.Width / 2, rect.Height / 2);
double RectRadius = Math.Sqrt(Math.Pow(rect.Width, 2) + Math.Pow(rect.Height, 2)) / 2;
double Dist_RC_P1 = RectCenter.DistanceFrom(pt1);
double Dist_RC_P2 = RectCenter.DistanceFrom(pt2);
if (Dist_RC_P1 <= RectRadius || Dist_RC_P2 <= RectRadius)
{
return(true);
}
else
{
double A, B, C;
CalcLineGeneralFunction(pt1, pt2, out A, out B, out C);
double Dist_RC_FP = GetDistanceBetweenPointAndLine(RectCenter, A, B, C);
if (Dist_RC_FP > RectRadius)
{
return(false);
}
else
{
if ((A * pt1.X + B * pt1.Y + C) * (A * pt2.X + B * pt2.Y + C) > 0)
{
return(false);
}
else
{
return(true);
}
}
}
}
}
/// <summary>
/// 判断在一个圆内部能否看到一个点。
/// </summary>
/// <param name="pt">点。</param>
/// <param name="offset">圆的圆心。</param>
/// <param name="radius">圆的半径。</param>
/// <returns>布尔值，表示在一个圆内部能否看到一个点。</returns>
public static bool PointIsVisibleInCircle(PointD pt, PointD offset, double radius)
{
if (pt.IsNaNOrInfinity || offset.IsNaNOrInfinity || (InternalMethod.IsNaNOrInfinity(radius) || radius <= 0))
{
return(false);
}
else
{
return(pt.DistanceFrom(offset) < radius);
}
}
/// <summary>
/// 判断在一个圆内部能否看到一个直线段的部分或全部。
/// </summary>
/// <param name="pt1">直线段的第一个端点。</param>
/// <param name="pt2">直线段的第二个端点。</param>
/// <param name="offset">圆的圆心。</param>
/// <param name="radius">圆的半径。</param>
/// <returns>布尔值，表示在一个圆内部能否看到一个直线段的部分或全部。</returns>
public static bool LineIsVisibleInCircle(PointD pt1, PointD pt2, PointD offset, double radius)
{
if (pt1.IsNaNOrInfinity || pt2.IsNaNOrInfinity || offset.IsNaNOrInfinity || (InternalMethod.IsNaNOrInfinity(radius) || radius <= 0))
{
return(false);
}
else
{
double Dist_Off_P1 = offset.DistanceFrom(pt1);
double Dist_Off_P2 = offset.DistanceFrom(pt2);
if (Dist_Off_P1 <= radius || Dist_Off_P2 <= radius)
{
return(true);
}
else
{
double A, B, C;
CalcLineGeneralFunction(pt1, pt2, out A, out B, out C);
double Dist_Off_FP = GetDistanceBetweenPointAndLine(offset, A, B, C);
if (Dist_Off_FP > radius)
{
return(false);
}
else
{
if ((A * pt1.X + B * pt1.Y + C) * (A * pt2.X + B * pt2.Y + C) > 0)
{
return(false);
}
else
{
return(true);
}
}
}
}
}
/// <summary>
/// 计算平面直角坐标系中过一个定点到一条直线的距离。
/// </summary>
/// <param name="pt">定点。</param>
/// <param name="pt1">直线上的第一个点。</param>
/// <param name="pt2">直线上的第二个点。</param>
/// <returns>双精度浮点数，表示平面直角坐标系中过一个定点到一条直线的距离。</returns>
public static double GetDistanceBetweenPointAndLine(PointD pt, PointD pt1, PointD pt2)
{
if (pt.IsNaNOrInfinity || pt1.IsNaNOrInfinity || pt2.IsNaNOrInfinity)
{
return(double.NaN);
}
else
{
if (pt1 == pt2)
{
return(pt.DistanceFrom(pt1));
}
else
{
double A, B, C;
CalcLineGeneralFunction(pt1, pt2, out A, out B, out C);
return(GetDistanceBetweenPointAndLine(pt, A, B, C));
}
}
}
