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 = 0, j = particleSystems.Length; i < j; i++)
                    {
                        var ps = particleSystems[i];
                        var mat = ps.GetComponent<Renderer>().material;
                        string shaderName = mat.shader.name + " 1";     // 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 = 0, j = renders.Length; i < j; i++)
                    {
                        var ps = renders[i];
                        var mat = ps.material;
                        string shaderName = mat.shader.name + " 1";     // 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 = 0; 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 > 0)
            {
                for (int i = 0; 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 = 0; 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 = 2;
            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 / 2,
                y = -clipRegion.w / 2,
                z = clipRegion.z / 2,
                w = clipRegion.w / 2
            };

            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
            };
        }


    }
}