// 区域相交
private bool isRegionCross(MBR m1, MBR m2)
{
/*
* [矩形相交](https://blog.csdn.net/qq_40482358/article/details/86537747)
* cx1=max(ax1,bx1) //左下x为最大的左下x集合
* cy1=max(ay1,by1) //左下y为最大的左下y集合
* cx2=min(ax2,bx2) //右上x为最小的右上x集合
* cy2=min(ay2,by2) //右上y为最小的右上y集合
* 矩形相交后仍然是矩形
*/
float cx1 = Math.Max(m1.left, m2.left);
float cy1 = Math.Max(m1.bottom, m2.bottom);
float cx2 = Math.Min(m1.right, m2.right);
float cy2 = Math.Min(m1.top, m2.top);
if (cx1 > cx2)
{
return(false);
}
if (cy1 > cy2)
{
return(false);
}
return(true);
}
private bool isPointInRegion(float x, float z, MBR mbr)
{
//
if (x < mbr.left || x > mbr.right || z > mbr.top || z < mbr.bottom)
{
return(false);
}
return(true);
}
// 初始化四叉树范围
public void Init(MBR mbr)
{
if (null != _root)
{
return;
}
_root = new QuadNode();
_root.mbr = mbr;
_root.Quadrant = EQuadrant.ROOT;
_root.Level = 0;
// debug
LevelCnt = new Dictionary <int, int>();
TotalCnt = 0;
CorssCircleTestCnt = 0;
// debug
}
// 判断mbr和圆是否相交
private bool isCrossCricle(MBR mbr, Circle circle)
{
CorssCircleTestCnt++;
// 1. 矩形的四点判断 点在圆内
// 2. 矩形的四边判断 边与圆相交
// [算法](https://www.cnblogs.com/llkey/p/3707351.html)
// 01 点在圆内
if (isPointInCricle(mbr.left, mbr.top, circle))
{
return(true);
}
else if (isPointInCricle(mbr.right, mbr.top, circle))
{
return(true);
}
else if (isPointInCricle(mbr.right, mbr.bottom, circle))
{
return(true);
}
else if (isPointInCricle(mbr.left, mbr.bottom, circle))
{
return(true);
}
// 02 边与圆相交
float rec_x = (mbr.right - mbr.left) * 0.5f;
float rec_z = (mbr.top - mbr.bottom) * 0.5f;
float deltaX = Math.Abs(rec_x - circle.x);
float deltaZ = Math.Abs(rec_z - circle.z);
if (deltaX * deltaX + deltaZ * deltaZ <= circle.radius * circle.radius)
{
return(true);
}
// 03 圆点在矩形内
if (isPointInRegion(circle.x, circle.z, mbr))
{
return(true);
}
return(false);
}
// mbr被圆包围
private bool isInCircle(MBR mbr, Circle circle)
{
CorssCircleTestCnt++;
if (false == isPointInCricle(mbr.left, mbr.top, circle))
{
return(false);
}
if (false == isPointInCricle(mbr.right, mbr.top, circle))
{
return(false);
}
if (false == isPointInCricle(mbr.right, mbr.bottom, circle))
{
return(false);
}
if (false == isPointInCricle(mbr.left, mbr.bottom, circle))
{
return(false);
}
return(true);
}
// 象限分裂
// 分裂后，node节点的数据，尝试插入到子象限内
private void split(QuadNode node)
{
// 已经分裂过了
if (null != node.Sub)
{
return;
}
// 分裂为四个象限
/*
|
|
| UL | UR
| ---------------------
|
| LL | LR
|
|
*/
// mbr = (x,z,w,l)
var mbr = node.mbr;
float hw = (mbr.right - mbr.left) * 0.5f;
float hl = (mbr.top - mbr.bottom) * 0.5f;
var mbr_ur = new MBR(mbr.right - hw, mbr.right, mbr.top, mbr.top - hl);
var mbr_ul = new MBR(mbr.left, mbr.left + hw, mbr.top, mbr.top - hl);
var mbr_ll = new MBR(mbr.left, mbr.left + hw, mbr.bottom + hl, mbr.bottom);
var mbr_lr = new MBR(mbr.right - hw, mbr.right, mbr.bottom + hl, mbr.bottom);
node.Sub = new QuadNode[4];
node.Sub[0] = new QuadNode()
{
Level = node.Level + 1, Quadrant = EQuadrant.UR, Cnt = 0, mbr = mbr_ur, Child = null, Sub = null,
};
node.Sub[1] = new QuadNode()
{
Level = node.Level + 1, Quadrant = EQuadrant.UL, Cnt = 0, mbr = mbr_ul, Child = null, Sub = null,
};
node.Sub[2] = new QuadNode()
{
Level = node.Level + 1, Quadrant = EQuadrant.LL, Cnt = 0, mbr = mbr_ll, Child = null, Sub = null,
};
node.Sub[3] = new QuadNode()
{
Level = node.Level + 1, Quadrant = EQuadrant.LR, Cnt = 0, mbr = mbr_lr, Child = null, Sub = null,
};
if (node.Level + 1 > Current_Max_Level)
{
Current_Max_Level = node.Level + 1;
}
// 尝试插入当前节点的child
TotalCnt -= node.Cnt;
LevelCnt[node.Level] -= node.Cnt;
node.Cnt = 0;
if (node.Child != null)
{
var tmp = node.Child;
var tmp1 = tmp.Next;
node.Child = null;
while (null != tmp)
{
Add(tmp);
tmp = tmp1;
if (null != tmp)
{
tmp1 = tmp.Next;
tmp.Next = null;
}
}
}
}