/// <summary>
/// 获取离边界最近的一条边（边可以不再边界上）
/// </summary>
/// <param name="origin"></param>
/// <param name="border"></param>
/// <returns></returns>
public static Vector getNearestVector(Dot2 origin, Border border)
{
if (border.DotCount < 2)
{
return(null);
}
int j1 = 0, j2 = 1;
double lengh1 = Math.Length(origin, border.get(j1)), lengh2 = Math.Length(origin, border.get(j2)), temp;
if (lengh1 > lengh2)
{
lengh1 = lengh1 + lengh2;
lengh2 = lengh1 - lengh2;
lengh1 = lengh1 - lengh2;
}
for (int i = 1; i < border.DotCount; i++)
{
temp = Math.Length(origin, border.get(i));
if (temp <= lengh1)
{
lengh2 = lengh1;
lengh1 = temp;
j2 = j1;
j1 = i;
}
else if (temp > lengh1 && temp <= lengh2)
{
lengh2 = temp;
j2 = i;
}
}
return(new Vector(border.get(j1), border.get(j2)));
}
/// <summary>
/// 判断点是否在边界内
/// </summary>
/// <param name="dot"></param>
/// <param name="border"></param>
/// <returns></returns>
public static bool isInside(Dot2 dot, Border border)
{
int num = 0;
//double minx, maxx;
for (int i = 0; i < border.DotCount - 1; i++)
{
if (dot.X <= (System.Math.Max(border.get(i).X, border.get(i + 1).X)) && (border.get(i).Y - dot.Y) * (border.get(i + 1).Y - dot.Y) < 0)
{
if (dot.X > System.Math.Min(border.get(i).X, border.get(i + 1).X))
{
if ((border.get(i).X *border.get(i + 1).Y - border.get(i).Y *border.get(i + 1).X + dot.Y * (border.get(i + 1).X - border.get(i).X)) / (border.get(i + 1).Y - border.get(i).Y) > dot.X)
{
num++;
}
}
else
{
num++;
}
}
}
if (num % 2 == 1)
{
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// 将增加长度最小的点插入
/// </summary>
/// <param name="origin"></param>
/// <param name="border"></param>
public static void putMinLengthDotToBorder(Dot2 origin, Border border)
{
double temp, lengh = double.MaxValue;
if (border.DotCount <= 2)
{
border.Add(origin);
return;
}
int j = 0;
for (int i = 0; i < border.DotCount; i++)
{
temp = Math.Length(origin, border.get(i)) + Math.Length(origin, border.get(i + 1)) - border.getVecter(i).Length;
if (temp < lengh)
{
lengh = temp;
j = i;
}
}
border.Insert(origin, j + 1, DrawType.Ignore);
}
/// <summary>
/// 将一个点插入到边界中，形成凸面体
/// </summary>
/// <param name="origin"></param>
/// <param name="border"></param>
/// <returns></returns>
public static void putDotToBorder(Dot2 origin, Border border)
{
Dot2 dot;
int i, j = 0, count = border.DotCount, tempj;
if (count <= 2)
{
border.Add(origin);
return;
}
double temp, lengh = double.MaxValue;
int isIntersects = 0;
for (i = 0; i < count; i++)
{
temp = Math.Length(origin, border.get(i));
if (temp < lengh)
{
lengh = temp;
j = i;
}
}
//判断是否相交
tempj = count + j;
for (i = 0; i < count; i++)
{
if (i == tempj % count || i == (tempj - 1) % count)
{
continue;
}
if (isIntersect(new Vector(origin, border.get(tempj)), border.getVecter(i), out dot))
{
isIntersects = 1;
break;
}
}
if (isIntersects == 1)
{
isIntersects = 4;
lengh = double.MaxValue;
//采用面积最小方式
for (i = 0; i < border.DotCount; i++)
{
temp = Math.Area(origin, border.get(i), border.get((i + 1)));
if (temp < lengh)
{
lengh = temp;
j = i;
}
}
//判断是否相交,若相交，取最近的相交的线段插入
temp = double.MaxValue;
tempj = count + j;
for (i = 0; i < count; i++)
{
if (i == tempj % count || i == (tempj - 1) % count)
{
continue;
}
if (isIntersect(new Vector(origin, border.get(tempj)), border.getVecter(i), out dot))
{
temp = Math.Length(origin, dot);
if (temp < lengh)
{
isIntersects = 5;
lengh = temp;
j = i;
}
}
}
//if (isIntersects == 5)
//{
//}
//tempj = count + i+1;
//for (i = 0; i < count; i++)
//{
// if (i == tempj % count || i == (tempj - 1) % count)
// {
// continue;
// }
// if (isIntersect(new Vector(origin, border.get(tempj)), border.getVecter(i), out dot))
// {
// isIntersects = 5;
// break;
// }
//}
}
else
{
tempj = count + j - 1;
for (i = 0; i < count; i++)
{
if (i == tempj % count || i == (tempj - 1) % count)
{
continue;
}
if (isIntersect(new Vector(origin, border.get(tempj)), border.getVecter(i), out dot))
{
isIntersects = 1;
break;
}
}
tempj = count + j + 1;
for (i = 0; i < count; i++)
{
if (i == tempj % count || i == (tempj - 1) % count)
{
continue;
}
if (isIntersect(new Vector(origin, border.get(tempj)), border.getVecter(i), out dot))
{
if (isIntersects == 1)
{
isIntersects = 2;
}
else
{
isIntersects = 3;
}
break;
}
}
}
switch (isIntersects)
{
case 0: //两线段都无交点
if (Math.Length(origin, border.get(j - 1)) + border.getVecter(j).Length > Math.Length(origin, border.get(j + 1)) + border.getVecter(j - 1).Length)
{
border.Insert(origin, j + 1, DrawType.normal);
}
else
{
border.Insert(origin, j, DrawType.normal);
}
break;
case 1: //仅左线段相交
border.Insert(origin, j + 1, DrawType.Ignore);
break;
case 2: //左右线段都相交
break;
case 3: //仅右线段相交
border.Insert(origin, j, DrawType.Ignore);
break;
case 4: //采用面积最小方式,无相交
border.Insert(origin, j + 1, DrawType.Ignore);
break;
case 5: //采用面积最小方式,有相交,插入相交线段
border.Insert(origin, j + 1, DrawType.Ignore);
break;
default:
break;
}
}
