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using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CalculationIntersection1 : MonoBehaviour
{
public Transform a; //A1
public Transform b; //A2
public Transform c; //B
public Transform d;
public Vector2 GetIntersection(Vector2 lineAStart, Vector2 lineAEnd, Vector2 lineBStart, Vector2 lineBEnd)
{
float x1 = lineAStart.x, y1 = lineAStart.y;
float x2 = lineAEnd.x, y2 = lineAEnd.y;
float x3 = lineBStart.x, y3 = lineBStart.y;
float x4 = lineBEnd.x, y4 = lineBEnd.y;
//两向量相互垂直,返回0
if (x1 == x2 && x3 == x4 && x1 == x3)
{
return Vector2.zero;
}
//两向量相互平行。返回0
if (y1 == y2 && y3 == y4 && y1 == y3)
{
return Vector2.zero;
}
//两向量相互垂直,返回0
if (x1 == x2 && x3 == x4)
{
return Vector2.zero;
}
//两向量相互平行。返回0
if (y1 == y2 && y3 == y4)
{
return Vector2.zero;
}
float x, y;
if (x1 == x2)
{
float m2 = (y4 - y3) / (x4 - x3);
float c2 = -m2 * x3 + y3;
x = x1;
y = c2 + m2 * x1;
}
else if (x3 == x4)
{
float m1 = (y2 - y1) / (x2 - x1);
float c1 = -m1 * x1 + y1;
x = x3;
y = c1 + m1 * x3;
}
else
{
float m1 = (y2 - y1) / (x2 - x1);
float c1 = -m1 * x1 + y1;
float m2 = (y4 - y3) / (x4 - x3);
float c2 = -m2 * x3 + y3;
x = (c1 - c2) / (m2 - m1);
y = c2 + m2 * x;
}
if (IsInsideLine(lineAStart, lineAEnd, x, y) &&
IsInsideLine(lineBStart, lineBEnd, x, y))
{
return new Vector2(x, y);
}
return Vector2.zero;
}
//交点是否在线以内
private bool IsInsideLine(Vector3 start, Vector3 end, float x, float y)
{
return ((x >= start.x && x <= end.x)
|| (x >= end.x && x <= start.x))
&& ((y >= start.y && y <= end.y)
|| (y >= end.y && y <= start.y));
}
/// <summary>
/// 判断点位是否在一条直线上
/// </summary>
/// <param name="Pos1"></param>
/// <param name="Pos2"></param>
/// <param name="Pos3"></param>
/// <returns></returns>
public bool PosInLine(Vector3 Pos1, Vector3 Pos2, Vector3 Pos3)
{
Vector3 dirA = (Pos1 - Pos2).normalized;
Vector3 dirB = new Vector3(
Mathf.Abs(dirA.x),
Mathf.Abs(dirA.y),
Mathf.Abs(dirA.z)
).normalized;
Vector3 dirC = (Pos3 - Pos1).normalized;
Vector3 dirD = new Vector3(
Mathf.Abs(dirC.x),
Mathf.Abs(dirC.y),
Mathf.Abs(dirC.z)
).normalized;
if (dirB == dirD)
{
return true;
}
else
{
return false;
}
}
private void OnDrawGizmos()
{
Gizmos.color = Color.red;
Gizmos.DrawLine(a.position, b.position);
Gizmos.color = Color.yellow;
Gizmos.DrawLine(a.position, c.position);
Vector3 dirAB = (b.position - a.position).normalized;
Vector3 verticalABDir = (Vector3.Dot(Vector3.up, dirAB) * (-dirAB) + Vector3.up).normalized; //直线的垂线
Vector3 horizontalABDir = Vector3.Cross(dirAB, verticalABDir).normalized;
Vector3 aa = c.position - horizontalABDir * 10;
Vector3 bb = c.position + horizontalABDir * 10;
Vector2 pos = GetIntersection(new Vector2(a.position.x, a.position.z),
new Vector2(b.position.x, b.position.z),
new Vector2(c.position.x, c.position.z),
new Vector2(aa.x, aa.z));
if (pos == Vector2.zero)
{
Gizmos.DrawLine(c.position, bb);
Vector2 pos1 = GetIntersection(new Vector2(a.position.x, a.position.z),
new Vector2(b.position.x, b.position.z),
new Vector2(c.position.x, c.position.z),
new Vector2(bb.x, bb.z));
d.position = new Vector3(pos1.x, 0, pos1.y);
}
else
{
Gizmos.DrawLine(c.position, aa);
d.position = new Vector3(pos.x, 0, pos.y);
}
Debug.Log(PosInLine(a.position,b.position,c.position));
}
}
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