Unity NGUI 多个UIPanel对粒子的剪裁

之前写过一篇单个 UIPanel 对粒子的裁剪，地址是：https://www.cnblogs.com/jietian331/p/5075487.html

但项目中有时会遇到多个UIPanel，如下面问题，UISprite 被剪裁了，但粒子未被剪裁：

转载请注明出处：https://www.cnblogs.com/jietian331/p/10938837.html

这时解决问题的思路是，找出所有的有剪裁功能的 UIPanel，并求出它们剪裁区域的交集然后传到shader中，效果如下：

代码如下：

 using System.Collections.Generic;
 using UnityEngine;

 namespace Modules.UI
 {
     // 对子节点下所有的粒子和模型进行剪裁，且支持多个 UIPanel
     public class EffectClip : MonoBehaviour
     {
         List<Material> m_materials;
         List<UIPanel> m_uiPanels;
         UIRoot m_uiRoot;

         #region Properties

         UIRoot ObjUIRoot
         {
             get
             {
                 if (!m_uiRoot)
                     m_uiRoot = GetComponentInParent<UIRoot>();
                 return m_uiRoot;
             }
         }

         // 找到所有粒子，模型的material
         List<Material> Materials
         {
             get
             {
                 if (m_materials == null)
                 {
                     m_materials = new List<Material>();

                     // particle system 的剪裁
                     var particleSystems = GetComponentsInChildren<ParticleSystem>();
                     for (int i = , j = particleSystems.Length; i < j; i++)
                     {
                         var ps = particleSystems[i];
                         var mat = ps.GetComponent<Renderer>().material;
                         string shaderName = mat.shader.name + "";     // 所用shader，重写一份带剪裁功能的
                         Shader shader = Shader.Find(shaderName);
                         if (shader)
                         {
                             m_materials.Add(mat);
                             mat.shader = shader;
                         }
                         else
                         {
                             Debug.LogError("Shader not found, name: " + shaderName);
                         }
                     }

                     // mesh 的剪裁
                     var renders = GetComponentsInChildren<MeshRenderer>();
                     for (int i = , j = renders.Length; i < j; i++)
                     {
                         var ps = renders[i];
                         var mat = ps.material;
                         string shaderName = mat.shader.name + "";     // 所用shader，重写一份带剪裁功能的
                         Shader shader = Shader.Find(shaderName);
                         if (shader)
                         {
                             m_materials.Add(mat);
                             mat.shader = shader;
                         }
                         else
                         {
                             Debug.LogError("Shader not found, name: " + shaderName);
                         }
                     }
                 }
                 return m_materials;
             }
         }

         List<UIPanel> Panels
         {
             get
             {
                 if (m_uiPanels == null)
                 {
                     // 获取所有开启剪裁的 UIPanel
                     m_uiPanels = new List<UIPanel>();
                     UIPanel[] panels = GetComponentsInParent<UIPanel>();
                     for (int i = ; i < panels.Length; i++)
                     {
                         UIPanel p = panels[i];
                         if (p && p.clipping == UIDrawCall.Clipping.SoftClip)
                         {
                             m_uiPanels.Add(p);
                         }
                     }
                 }
                 return m_uiPanels;
             }
         }

         #endregion

         void Update()
         {
             var mats = Materials;
             if (mats != null && mats.Count > )
             {
                 for (int i = ; i < m_materials.Count; i++)
                 {
                     Vector4 area = CalcClipArea();
                     m_materials[i].SetVector("_Area", area);
                 }
             }
         }

         // 整合所有 UIPanel 的剪裁区域
         Vector4 CalcClipArea()
         {
             var panels = Panels;
             float x = float.MinValue, y = float.MinValue, z = float.MaxValue, w = float.MaxValue;

             // 求所有 UIPanel 剪裁区域的交集
             for (int i = ; i < panels.Count; i++)
             {
                 UIPanel p = panels[i];
                 Vector4 area = CalcClipArea(p);

                 // 求交集啊
                 if (area.x > x)
                     x = area.x;
                 if (area.y > y)
                     y = area.y;
                 if (area.z < z)
                     z = area.z;
                 if (area.w < w)
                     w = area.w;
             }

             return new Vector4(x, y, z, w);
         }

         // 计算单个 UIPanel 的剪裁区域
         Vector4 CalcClipArea(UIPanel p)
         {
             float h = ;
             float temp = h / ObjUIRoot.activeHeight;
             Vector3 offsetV3 = new Vector3()
             {
                 x = p.clipOffset.x * temp,
                 y = p.clipOffset.y * temp,
             };
             Vector3 worldPos = p.transform.position + offsetV3;
             Vector4 clipRegion = p.finalClipRegion;
             Vector4 nguiArea = new Vector4()
             {
                 x = -clipRegion.z / ,
                 y = -clipRegion.w / ,
                 z = clipRegion.z / ,
                 w = clipRegion.w /
             };

             return new Vector4()
             {
                 x = worldPos.x + nguiArea.x * temp,
                 y = worldPos.y + nguiArea.y * temp,
                 z = worldPos.x + nguiArea.z * temp,
                 w = worldPos.y + nguiArea.w * temp
             };
         }

     }
 }

EffectClip