Unity使用拖尾渲染器模拟简易的管道流体

发表于2018-03-01
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拖尾渲染器主要用于制作跟在场景中的物体后面的拖尾效果来代表它们在到处移动,本篇文章和大家分享的是如何使用拖尾渲染器模拟简易的管道流体,一起来看看吧。

关于管道流体
相信只要是做虚拟仿真的,或多或少都会接触过这种需求,当然解决的最佳方案就是UV动画,在网上看过很多例子几乎都是这样的,毕竟用实时流体计算的话开销确实太大,用粒子系统的话又苦于难以表现出流体的粘稠性,只不过最近在用TrailRenderer模拟管道流体之后,感觉效果还是不错的,所以在这里将技巧分享出来,没什么技术含量。

看一下效果:


首先,实现管道路径
因为TrailRenderer可以通过设置Corner Vertices(拐角处顶点数量)来自动圆角,所以不用考虑使用任何曲线算法,这样还能保证我们的路径点绝对的贴合管道,毕竟管道模型可能会有你意想不到的弯曲复杂度。

不过我们为了要保证流体在管道的每一个位置都保持相同速度流动,所以必须为每一个路段指定不同的流动速度。
管道流体实例类:PipeFlow.cs
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PipeFlow : MonoBehaviour {
    public FlowItem ItemTemplate;
    public float FlowTime = 1f;
    public float FlowInterval = 0.5f;
    public bool OnlyOnce = false;
    [HideInInspector]
    public List<Vector3> FlowPath = new List<Vector3>();
    [HideInInspector]
    public List<float> FlowSpeeds = new List<float>();
    [HideInInspector]
    public List<FlowItem> Items = new List<FlowItem>();
    private bool _isInit = false;
    private bool _isFlowing = false;
    private float _flowInterval = 0f;
    private Action _actionTrigger;
    private Coroutine _actionCoroutine;
    private void Awake()
    {
        if (!_isInit)
        {
            Init();
        }
    }
    private void Init()
    {
        float tatol = 0f;
        for (int i = 0; i < FlowPath.Count - 1; i++)
        {
            tatol += Vector3.Distance(FlowPath[i], FlowPath[i + 1]);
        }
        for (int i = 0; i < FlowPath.Count - 1; i++)
        {
            float dis = Vector3.Distance(FlowPath[i], FlowPath[i + 1]);
            float time = dis / tatol * (FlowTime * 50);
            FlowSpeeds.Add(1f / time);
        }
        _isInit = true;
    }
    private void Update()
    {
        if (_isFlowing)
        {
            _flowInterval += Time.deltaTime;
            if (_flowInterval >= FlowInterval)
            {
                _flowInterval = 0f;
                ShootItem();
                if (OnlyOnce)
                {
                    _isFlowing = false;
                }
            }
        }
    }
    private void ShootItem()
    {
        if (Items.Count > 0)
        {
            Items[0].Shoot(this);
            Items.RemoveAt(0);
        }
        else
        {
            GameObject item = Instantiate(ItemTemplate.gameObject);
            item.transform.parent = transform;
            item.GetComponent<FlowItem>().Shoot(this);
        }
    }
    public void Flow(Action endAction)
    {
        if (FlowPath.Count < 2)
        {
            Debug.LogWarning("路径点数量必须大于等于2!");
            return;
        }
        if (!ItemTemplate)
        {
            Debug.LogWarning("ItemTemplate不能为空!");
            return;
        }
        if (!_isInit)
        {
            Init();
        }
        _isFlowing = true;
        _flowInterval = FlowInterval;
        _actionTrigger = endAction;
        if (_actionCoroutine != null)
        {
            StopCoroutine(_actionCoroutine);
            _actionCoroutine = null;
        }
        if (_actionTrigger != null)
        {
            _actionCoroutine = StartCoroutine(DelayExecute(_actionTrigger, FlowTime));
        }
    }
    public void Stop()
    {
        _isFlowing = false;
        if (_actionCoroutine != null)
        {
            StopCoroutine(_actionCoroutine);
            _actionCoroutine = null;
        }
        FlowItem[] fis = transform.GetComponentsInChildren<FlowItem>();
        foreach (FlowItem fi in fis)
        {
            fi.Stop();
        }
    }
    public static IEnumerator DelayExecute(Action action, float delaySeconds)
    {
        yield return new WaitForSeconds(delaySeconds);
        action();
    }
}

该类的编辑器重写:PipeFlowEditor.cs
using UnityEngine;
using UnityEditor;
[CustomEditor(typeof(PipeFlow)), CanEditMultipleObjects]
public class PipeFlowEditor : Editor 
{
    private PipeFlow _pipeFlow;
    private int _currentIndex = -1;
    private bool _showInEditor = true;
    private void OnEnable()
    {
        _pipeFlow = target as PipeFlow;
    }
    public override void OnInspectorGUI()
    {
        base.OnInspectorGUI();
        EditorGUILayout.BeginVertical("HelpBox");
        EditorGUILayout.BeginHorizontal();
        GUILayout.Label("FlowPath");
        _showInEditor = GUILayout.Toggle(_showInEditor, "Show In Editor");
        EditorGUILayout.EndHorizontal();
        if (_showInEditor)
        {
            EditorGUILayout.BeginHorizontal();
            if (GUILayout.Button("路径倒置", "ButtonLeft"))
            {
                if (EditorUtility.DisplayDialog("提示", "是否将整条路径倒置?", "是的", "我再想想"))
                {
                    if (_pipeFlow.FlowPath.Count > 1)
                    {
                        _pipeFlow.FlowPath.Reverse();
                    }
                }
            }
            if (GUILayout.Button("清空路径点", "ButtonRight"))
            {
                if (EditorUtility.DisplayDialog("提示", "是否清空路径点?", "是的", "我再想想"))
                {
                    _pipeFlow.FlowPath.Clear();
                    _currentIndex = -1;
                }
            }
            EditorGUILayout.EndHorizontal();
            for (int i = 0; i < _pipeFlow.FlowPath.Count; i++)
            {
                EditorGUILayout.BeginHorizontal();
                GUI.backgroundColor = _currentIndex == i ? Color.cyan : Color.white;
                if (GUILayout.Button("path point" + (i + 1), "prebutton"))
                {
                    _currentIndex = i;
                    Tools.current = Tool.None;
                }
                GUI.backgroundColor = Color.white;
                if (GUILayout.Button("", "OL Minus", GUILayout.Width(16)))
                {
                    _pipeFlow.FlowPath.RemoveAt(i);
                    _currentIndex = -1;
                }
                EditorGUILayout.EndHorizontal();
            }
            EditorGUILayout.BeginHorizontal();
            GUILayout.FlexibleSpace();
            if (GUILayout.Button("", "OL Plus", GUILayout.Width(16)))
            {
                if (_currentIndex != -1)
                {
                    _pipeFlow.FlowPath.Add(_pipeFlow.FlowPath[_currentIndex]);
                }
                else
                {
                    _pipeFlow.FlowPath.Add(new Vector3(0, 0, 0));
                }
            }
            EditorGUILayout.EndHorizontal();
        }
        EditorGUILayout.EndVertical();
    }
    private void OnSceneGUI()
    {
        if (_showInEditor)
        {
            Handles.color = Color.cyan;
            if (_pipeFlow.FlowPath.Count > 0)
            {
                Handles.Label(_pipeFlow.FlowPath[0], "[" + _pipeFlow.transform.name + "]起点", "ErrorLabel");
            }
            if (_pipeFlow.FlowPath.Count > 1)
            {
                Handles.Label(_pipeFlow.FlowPath[_pipeFlow.FlowPath.Count - 1], "[" + _pipeFlow.transform.name + "]终点", "ErrorLabel");
            }
            for (int i = 0; i < _pipeFlow.FlowPath.Count; i++)
            {
                if (i < _pipeFlow.FlowPath.Count - 1)
                    Handles.DrawLine(_pipeFlow.FlowPath[i], _pipeFlow.FlowPath[i + 1]);
            }
            if (_currentIndex != -1)
            {
                _pipeFlow.FlowPath[_currentIndex] = Handles.PositionHandle(_pipeFlow.FlowPath[_currentIndex], Quaternion.identity);
            }
        }
    }
}

流体因子
每一个流体因子携带一个拖尾渲染器,由PipeFlow根据其属性FlowInterval(间隔发射时间)进行持续发射(如果不是OnlyOnce模式),每一个流体因子从路径起点抵达路径终点的时间为FlowTime。
//PipeFlow.cs
public void Flow(Action endAction);

外部调用Flow为开启流体,参数endAction当第一个流体因子抵达管道路径终点时触发,可以为空。

流体因子类:FlowItem.cs
using UnityEngine;
public class FlowItem : MonoBehaviour {
    public float DelayDestroy = 0.5f;
    private bool _isFlowing = false;
    private PipeFlow _pipeFlow;
    private int _flowIndex = 0;
    private int _nextIndex = 1;
    private float _flowPosition = 0f;
    private Coroutine _stopCoroutine;
    private void Reset()
    {
        transform.position = _pipeFlow.FlowPath[0];
        TrailRenderer[] trails = GetComponentsInChildren<TrailRenderer>();
        for (int i = 0; i < trails.Length; i++)
        {
            trails[i].Clear();
        }
        ParticleSystem[] pss = GetComponentsInChildren<ParticleSystem>();
        for (int i = 0; i < pss.Length; i++)
        {
            pss[i].SetParticles(null, 0);
        }
    }
    private void Update()
    {
        if (_isFlowing)
        {
            _flowPosition += _pipeFlow.FlowSpeeds[_flowIndex];
            transform.position = Vector3.Lerp(_pipeFlow.FlowPath[_flowIndex], _pipeFlow.FlowPath[_nextIndex], _flowPosition);
            if (_flowPosition >= 1f)
            {
                if (_nextIndex >= _pipeFlow.FlowPath.Count - 1)
                {
                    _isFlowing = false;
                    _stopCoroutine = StartCoroutine(PipeFlow.DelayExecute(() => {
                        Stop();
                    }, DelayDestroy));
                }
                else
                {
                    _flowIndex += 1;
                    _nextIndex = _flowIndex + 1;
                    _flowPosition = 0f;
                }
            }
        }
    }
    public void Shoot(PipeFlow pipeFlow)
    {
        _pipeFlow = pipeFlow;
        Reset();
        gameObject.SetActive(true);
        _isFlowing = true;
        _flowIndex = 0;
        _nextIndex = 1;
        _flowPosition = 0f;
        if (_stopCoroutine != null)
        {
            StopCoroutine(_stopCoroutine);
            _stopCoroutine = null;
        }
    }
    public void Stop()
    {
        gameObject.SetActive(false);
        _isFlowing = false;
        if (!_pipeFlow.Items.Contains(this))
        {
            _pipeFlow.Items.Add(this);
        }
        if (_stopCoroutine != null)
        {
            StopCoroutine(_stopCoroutine);
            _stopCoroutine = null;
        }
    }
}

总共只需要如上的三个类文件就可以了,然后可以看下我TrailRenderer的属性设置,FlowItem的Delay Destroy属性为此流体因子延时消亡的时间,最好跟TrailRenderer的Time属性保持一致,这样的话才不会看到整条TrailRenderer突然消失的情况:

使用的纹理图片在这里:
来自:http://blog.csdn.net/qq992817263/article/details/79067356

原文链接

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