特效shader添加裁剪区域
使用裁剪区域进行裁剪, 粒子的shader得支持裁剪区域，需要在vert函数中加上下面的代码：
#ifdef UNITY_UI_CLIP_RECT c.a *= UnityGet2DClipping(i.worldPosition.xy, _ClipRect); //xy在裁剪矩形范围内就返回1, 否则返回0 clip(c.a - 0.001); #endif
上面的代码参考自UI-Default.shader
效果
下面的脚本用于把裁剪区域设置到Renderer的Material中，该脚本挂在Content或粒子上都行。
注意：Unity2018挂在Viewport-RectMask2D上也行，但在Unity2019中挂在Viewport-RectMask2D就不行了，应该是RectMask2D的实现有改动。
该代码是在MaskableGraphic的基础上精简下了，核心点：
1) 在裁剪回调函数SetClipRect中将裁剪区域设置到Renderer的Material中 2) 在事件函数(OnEnable, OnDisable, OnTransformParentChanged, OnCanvasHierarchyChanged)中把自己添加到RectMask2D的裁剪列表中using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class Clip3D : UIBehaviour, IClippable
{
[NonSerialized]
private RectTransform m_RectTransform;
[NonSerialized]
private RectMask2D m_ParentMask;
private List<Renderer> m_rendererList = new List<Renderer>();
private List<Material> m_matList = new List<Material>();
public RectTransform rectTransform
{
get
{
// The RectTransform is a required component that must not be destroyed. Based on this assumption, a
// null-reference check is sufficient.
if (ReferenceEquals(m_RectTransform, null))
{
m_RectTransform = GetComponent<RectTransform>();
}
return m_RectTransform;
}
}
public void SetClipSoftness(Vector2 clipSoftness)
{
//not implement
}
public void Cull(Rect clipRect, bool validRect)
{
//not implement
}
public virtual void SetClipRect(Rect clipRect, bool validRect)
{
Debug.Log($"({clipRect.xMin}, {clipRect.yMin}), ({clipRect.xMax}, {clipRect.yMax})"); //rootCanvas坐标空间下的, 我们这边要用世界坐标空间下的
GetComponentsInChildren<Renderer>(m_rendererList);
if (m_rendererList.Count > 0)
{
if (validRect)
{
var worldCorners = new Vector3[4]; //lb, lt, rt, rb
m_ParentMask.rectTransform.GetWorldCorners(worldCorners);
var worldClipRect = new Vector4(worldCorners[0].x, worldCorners[0].y, worldCorners[2].x, worldCorners[2].y);
foreach (var render in m_rendererList)
{
render.GetMaterials(m_matList);
if (m_matList.Count > 0)
{
foreach (var mat in m_matList)
{
if (null != mat && mat.HasProperty("_ClipRect"))
{
mat.SetVector("_ClipRect", worldClipRect);
mat.EnableKeyword("UNITY_UI_CLIP_RECT");
}
}
m_matList.Clear();
}
}
}
else
{
foreach (var render in m_rendererList)
{
render.GetMaterials(m_matList);
if (m_matList.Count > 0)
{
foreach (var mat in m_matList)
{
if (null != mat)
{
mat.DisableKeyword("UNITY_UI_CLIP_RECT");
}
}
m_matList.Clear();
}
}
}
m_rendererList.Clear();
}
}
protected override void OnEnable()
{
base.OnEnable();
UpdateClipParent();
}
protected override void OnDisable()
{
base.OnDisable();
UpdateClipParent();
}
#if UNITY_EDITOR
protected override void OnValidate()
{
base.OnValidate();
UpdateClipParent();
}
#endif
protected override void OnTransformParentChanged()
{
base.OnTransformParentChanged();
if (!isActiveAndEnabled)
return;
UpdateClipParent();
}
protected override void OnCanvasHierarchyChanged()
{
base.OnCanvasHierarchyChanged();
if (!isActiveAndEnabled)
return;
UpdateClipParent();
}
private void UpdateClipParent()
{
var newParent = IsActive() ? MaskUtilities.GetRectMaskForClippable(this) : null;
// if the new parent is different OR is now inactive
if (m_ParentMask != null && (newParent != m_ParentMask || !newParent.IsActive()))
{
m_ParentMask.RemoveClippable(this);
}
// don't re-add it if the newparent is inactive
if (newParent != null && newParent.IsActive())
newParent.AddClippable(this);
m_ParentMask = newParent;
}
/// <summary>
/// See IClippable.RecalculateClipping
/// </summary>
public virtual void RecalculateClipping()
{
UpdateClipParent();
}
}
粒子用到的支持裁剪的shader，这边仅仅为了演示随意写了一个(只求能看见粒子就行)
UnlitParticle.shader, UnlitParticle.mat
Shader "My/UnlitParticle"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
_ClipRect ("Clip Rect", Vector) = (0, 0, 0, 0)
}
SubShader
{
Tags
{
"RenderType"="Opaque"
}
LOD 100
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
#include "UnityUI.cginc"
#pragma multi_compile __ UNITY_UI_CLIP_RECT
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
float4 worldPosition : TEXCOORD1;
};
sampler2D _MainTex;
float4 _MainTex_ST;
float4 _ClipRect;
v2f vert (appdata v)
{
v2f o;
o.worldPosition = v.vertex;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _MainTex);
return o;
}
fixed4 frag (v2f i) : SV_Target
{
fixed4 c = tex2D(_MainTex, i.uv);
#ifdef UNITY_UI_CLIP_RECT
c.a *= UnityGet2DClipping(i.worldPosition.xy, _ClipRect);
clip(c.a - 0.001);
#endif
return c;
}
ENDCG
}
}
}
粒子的材质设置为UnlitParticle.mat，_ClipRect放在Properties中仅仅是为了在运行时看下裁剪区域点值(调试用)
Canvas不能用Overlay模式，否则粒子就看不到，因为Overlay模式，粒子不是直接在相机视口范围内
这边用Camera模式
UI相机得用正交相机，否则粒子会因为透视的原因(近大远小)，而导致裁剪区域不对
这边没处理到的问题
1) 粒子的层级问题，上面的粒子实际是白色的，但我们看到的是灰色的，因为粒子出现在了ScrollView背景的后面，这个涉及到ugui和3d物体的层级关系控制了，不在这边的处理范围，这边只处理裁剪
2) Renderer材质生成副本的问题，这个暂时还没想好
关于step函数
step(a, b)函数可以用于代替if (a>=b)的判断，它的逻辑：
if (a>=b)
return 0;
else
return 1;
UnityGet2DClipping函数
CGIncludes/UnityUI.cginc
inline float UnityGet2DClipping (in float2 position, in float4 clipRect)
{
float2 inside = step(clipRect.xy, position.xy) * step(position.xy, clipRect.zw);
return inside.x * inside.y;
}
参考
【Shader案例】实现UGUI裁剪功能_两水先木示的博客-CSDN博客_ugui scroll 裁剪3d模型 shader
Unity游戏开发-UI中裁剪特效_shitangdejiaozi的博客-CSDN博客
标签：特效,clipRect,mat,void,裁剪,matList,ScrollView,UI From： https://www.cnblogs.com/sailJs/p/17061809.html