Unity_简单2D锁链+锁链延伸
在做一个游戏时一个地方需要锁链，就在这记录一下
主要考虑方面：
1.锁链生成的主要输入：
锁链的两端位置
2.锁片总数限制
通过锁链两端位置、单个锁片的长度、锁片间的重叠比例，决定锁片总数
3.锁链长度实时变化
这里考虑的是，一条动态长度的锁链，当输入值发生变化时，锁链长度将自动改变。
4.误差过滤
在生成最后一块锁片时，应考虑 铰连接描点 的位置。因为在生成指定长度的锁链生成时，锁链总长度不可能等于输入的指定长度。
提示: 2D关节 顾名思义，关节将游戏物体连接在一起。
不清楚的建议去Unity官方文档看看，将所有关节尽可能的都用一遍。
5.锁链两端是否固定在空间某点或某物体上
需要注意铰连接的一特点：铰连接的刚体连接(Connected Rigid Body)为空的话“ 铰链连接” 的另一端将固定到“ 连接锚点”设置所定义的空间中的一点。
可由此实现固定于空间一点,至于固定到某物体上，只需将目标物体的刚体作为本铰连接的刚体连接(Connected Rigid Body)即可。
基本实现
公开方法
//在两点之间生成片段
public void DrawLength(Vector2 l,Vector2 r)
//清除不使用的片段，清除内存池中的过多对象
public void Clear()
调用案例
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
namespace MTest{
public class Manager : MonoBehaviour {
public Transform left;
public Transform right;
public Detent detent;
void Update () {
detent.DrawLength(left.position,right.position);
}
}
}
锁链类
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Detent : MonoBehaviour {
//单个锁片 信息记录
class Point{
public static Point left;
public static Point right;
public bool active{get{return root == null ? false : root.activeSelf;}}
public GameObject root;
public HingeJoint2D joint;
public HingeJoint2D joint2;
public Rigidbody2D rigidbody;
public Point(GameObject obj){
root = obj;
HingeJoint2D[] joints = obj.GetComponents<HingeJoint2D>();
joint = joints[0];
joint2 = joints[1];
rigidbody = obj.GetComponent<Rigidbody2D>();
}
public void Init(string name,Vector3 pos,Quaternion qua){
root.name = name;
root.transform.position = pos;
root.transform.rotation = qua;
rigidbody.velocity = Vector2.zero;
joint2.enabled = false;
Show();
}
public void Show(bool show = true){
if(show != root.activeSelf) root.SetActive(show);
}
}
public Transform content; //片段存放目标
private List<Point> mem = new List<Point>(); //片段内存池
public SpriteRenderer[] prefabs; //锁片 预制体
//当考虑生成的初始锁链为曲线时可自行改动长度并重新设计输入参数形式，这里没实现只了预留了下
public bool[] HangSegment; //锁片两端 是否固定与空间中
public bool useBendLimit = false; //使用片段弯曲限制
public int bendLimit = 45; //片段弯曲限制角度
public bool useBreakForce=false; //使用片段断裂界限
public float BreakForce = 100; //片段断裂峰值 --力
private Vector2 leftP; //左端点位置
private Vector2 rightP; //右端点位置
private Vector2 rightOff; //右端点偏移
[Range(-0.5f,0.5f)] public float overlapFactor; //重叠比例
[Range(0,0.5f)] public float minError = 0.25f; //允许的最小误差
public int maxLength = 50; //最大片段数
float segmentHeight; //片段长度
float yScale; //片段长度缩放
private void Awake() { Init(); }
//初始化
public void Init(){
yScale = prefabs[0].transform.localScale.y;
segmentHeight = prefabs[0].bounds.size.y * (1 + overlapFactor);
}
//在两点之间生成片段
public void DrawLength(Vector2 l,Vector2 r){
if(leftP != l || (rightP + rightOff)!= r){
leftP = l;
rightP = r;
Debug.DrawLine(leftP,rightP);
}
else return;
int i = 0;
float distance = Vector2.Distance(rightP,leftP);
int segmentCount = (int)(distance / segmentHeight);
float error = distance - segmentCount * segmentHeight;
bool fixError = error > minError * segmentHeight || segmentCount == 0;
int length = segmentCount;
if(maxLength <= segmentCount){
length = maxLength;
fixError = false;
rightOff = rightP - ((rightP-leftP).normalized * maxLength * segmentHeight + leftP);
rightP -= rightOff;
}
else{
rightOff = Vector2.zero;
}
for (; i < length; i++) AddPoint(i);
if(fixError) AddPoint(i++,true);
if(mem.Count > 0 && i > 0) Point.right = mem[i-1];
for (; i < mem.Count; i++) mem[i].Show(false);
if(!HangSegment[0]){
Point.left.joint.enabled = false;
}
if(HangSegment[1]){
Point.right.joint2.autoConfigureConnectedAnchor = false;
Point.right.joint2.connectedBody = null;
if(fixError){
Point.right.joint2.anchor = Point.right.root.transform.InverseTransformPoint(rightP);
}
else{
Point.right.joint2.anchor = new Vector2(0, segmentHeight / 2);
}
Point.right.joint2.connectedAnchor = rightP;
Point.right.joint2.enabled = true;
}
}
//清除不使用的片段
public void Clear(){
int i = 0,sum = mem.Count;
for (; i < sum; i++) if(!mem[i].active) break;
for (int j = i; j < sum; j++){
Destroy(mem[i].root);
mem.RemoveAt(i);
}
}
//添加片段 片段顺序 是否消除误差
private void AddPoint(int i,bool fix = false){
Point point;
if(i < mem.Count){
point = mem[i];
}
else{
GameObject obj = Instantiate(prefabs[i % 2],content).gameObject;
point = new Point(obj);
mem.Add(point);
}
float theta = Mathf.Atan2(rightP.y - leftP.y, rightP.x - leftP.x);
float dtheta = theta * Mathf.Rad2Deg;
if (dtheta > 180) dtheta -= 360;
else if (dtheta < -180) dtheta += 360;
float dx = segmentHeight * Mathf.Cos(theta);
float dy = segmentHeight * Mathf.Sin(theta);
float startX = leftP.x + dx / 2;
float startY = leftP.y + dy / 2;
point.Init(
"Segment_" + i+(fix ? "_fix":""),
new Vector3(startX + dx * i, startY + dy * i),
Quaternion.Euler(0, 0, theta * Mathf.Rad2Deg - 90)
);
if(i == 0){
Point.left = point;
point.joint.connectedAnchor = leftP;
point.joint.anchor = new Vector2(0, -segmentHeight / 2);
}
else{
AddJoint(dtheta, segmentHeight/ yScale, i-1, point);
}
}
//为片段添加关节
private void AddJoint(float dthetaT, float segmentHeightT, int index, Point point)
{
point.joint.connectedBody = mem[index].rigidbody;
point.joint.anchor = new Vector2(0, -segmentHeightT / 2);
point.joint.connectedAnchor = new Vector2(0, segmentHeightT / 2);
}
//使用片段角度限制与片段断裂峰值
private void LimitAndBreak(float dthetaT,Point point){
if (useBendLimit)
{
point.joint.useLimits = true;
point.joint.limits = new JointAngleLimits2D()
{
min = dthetaT - bendLimit,
max = dthetaT + bendLimit
};
}
if (useBreakForce) point.joint.breakForce = BreakForce;
}
}
效果参数 设置，或者可自行导入 package
