示意

2种效果，一种边缘模糊，一种边缘清晰。对应2种材质。

闭眼效果.gif

说明

将Img的材质设置为使用了Blink Shader的材质。

Shader

Blink（边缘模糊）

材质默认参数

 _img.material.SetVector("_Param", new Vector4(0.6f, y, 1, 1));

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
 
Shader "Custom/Blink"
{
    Properties
    {
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Tint", Color) = (1,1,1,1)
 
        _StencilComp("Stencil Comparison", Float) = 8
        _Stencil("Stencil ID", Float) = 0
        _StencilOp("Stencil Operation", Float) = 0
        _StencilWriteMask("Stencil Write Mask", Float) = 255
        _StencilReadMask("Stencil Read Mask", Float) = 255
 
        _ColorMask("Color Mask", Float) = 15
 
        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip("Use Alpha Clip", Float) = 0
 
        [Space(100)]
        _Param("Param", vector) = (0.6, 0.3, 1, 1)
    }
 
        SubShader
    {
        Tags
    {
        "Queue" = "Transparent"
        "IgnoreProjector" = "True"
        "RenderType" = "Transparent"
        "PreviewType" = "Plane"
        "CanUseSpriteAtlas" = "True"
    }
 
        Stencil
    {
        Ref[_Stencil]
        Comp[_StencilComp]
        Pass[_StencilOp]
        ReadMask[_StencilReadMask]
        WriteMask[_StencilWriteMask]
    }
 
        Cull Off
        Lighting Off
        ZWrite Off
        ZTest[unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha
        ColorMask[_ColorMask]
 
        Pass
    {
        Name "Default"
        CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0
 
#include "UnityCG.cginc"
#include "UnityUI.cginc"
 
#pragma multi_compile __ UNITY_UI_CLIP_RECT
#pragma multi_compile __ UNITY_UI_ALPHACLIP
 
 
        struct appdata_t
    {
        float4 vertex   : POSITION;
        float4 color    : COLOR;
        float2 texcoord : TEXCOORD0;
        UNITY_VERTEX_INPUT_INSTANCE_ID
    };
 
    struct v2f
    {
        float4 vertex   : SV_POSITION;
        fixed4 color : COLOR;
        float2 texcoord  : TEXCOORD0;
        float4 worldPosition : TEXCOORD1;
        UNITY_VERTEX_OUTPUT_STEREO
    };
 
    sampler2D _MainTex;
    fixed4 _Color;
    fixed4 _TextureSampleAdd;
    float4 _ClipRect;
    float4 _MainTex_ST;
    half3 _Param;
 
    v2f vert(appdata_t v)
    {
        v2f OUT;
        UNITY_SETUP_INSTANCE_ID(v);
        UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
        OUT.worldPosition = v.vertex;
        OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
 
        OUT.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
 
        OUT.color = v.color * _Color;
        return OUT;
    }
 
    fixed4 frag(v2f IN) : SV_Target
    {
        //half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;
        half4 color = IN.color;
        float x = IN.texcoord.x - 0.5;
        float y = IN.texcoord.y - 0.5;
        float oval = x * x / (_Param.x * _Param.x) + y * y / (_Param.y * _Param.y);
        color.a = oval;
 
#ifdef UNITY_UI_CLIP_RECT
        color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#endif
 
#ifdef UNITY_UI_ALPHACLIP
        clip(color.a - 0.001);
#endif
 
        return color;
    }
        ENDCG
    }
    }
}

Blink2（边缘清晰）

材质默认参数

 _img.material.SetFloat("_Height", y);

//对图片的mask处理,只有椭圆部分
Shader "Custom/Blink2"
{
    Properties
    {
        _MainTex("Base (RGB), Alpha (A)", 2D) = "black" {}
        _CenterX("CenterX", float) = 0.5
        _CenterY("CenterY", float) = 0.5
        _Width("Width", float) = 1.8
        _Height("Height", float) = 0.15
        _LengthRate("LengthRate", float) = 0.1 
        _LengthRateTransition("LengthRateLerp", float) = 0.01
    }

        SubShader
        {
            LOD 200

            Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
        }

            Pass
        {
            Cull Off
            Lighting Off
            ZWrite Off
            Fog{ Mode Off }
            Offset -1,-1
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM
    #pragma vertex vert
    #pragma fragment frag            
    #include "UnityCG.cginc"

            sampler2D _MainTex;
        half4 _MainTex_ST;
        half _CenterX;
        half _CenterY;
        half _Width;
        half _Height;
        half _LengthRate;
        half _LengthRateTransition;

        struct appdata_t
        {
            half4 vertex : POSITION;
            half2 texcoord : TEXCOORD0;
            fixed4 color : COLOR;
        };

        struct v2f
        {
            half4 vertex : SV_POSITION;
            half2 texcoord : TEXCOORD0;
            fixed4 color : COLOR;
        };

        v2f o;

        v2f vert(appdata_t v)
        {
            o.vertex = UnityObjectToClipPos(v.vertex);
            o.texcoord = v.texcoord;
            o.color = v.color;
            return o;
        }

        fixed4 frag(v2f IN) : COLOR
        {
            float2 pt = IN.texcoord - float2(_CenterX,(1 - _CenterY));
            float h = (pt.x*pt.x) / (_Width*_Width) + (pt.y*pt.y) / (_Height*_Height);

            float4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
            float sub = _LengthRate - h;
            if (h < _LengthRate && sub < _LengthRateTransition)
            {
                c.a = c.a - sub / _LengthRateTransition ;
                return c;
            }
            else if (h < _LengthRate)
            {
                discard;
            }

            return c;
        }
            ENDCG
        }
        }

            SubShader
        {
            LOD 100

            Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
        }

            Pass
        {
            Cull Off
            Lighting Off
            ZWrite Off
            Fog{ Mode Off }
            Offset -1,-1
            ColorMask RGB
            Blend SrcAlpha OneMinusSrcAlpha
            ColorMaterial AmbientAndDiffuse

            SetTexture[_MainTex]
        {
            Combine Texture * Primary
        }
        }
        }
}

测试代码

闭眼效果的y值变化

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class Blink : MonoBehaviour
{
    [SerializeField]
    private Image _img;
    [SerializeField,Header("最后一组的duration无实际作用！")]
    private BlinkData[] _data;
    [SerializeField]
    private Material[] _mats;
    private int _curMatId;
    private IEnumerator _blinkCoroutine;

    private void OnEnable() 
    {
        _curMatId = 0;
    }

    private void OnDestroy() 
    {
        SetValue(0);
    }

    public void ChangeMat()
    {
        _curMatId++;
        if (_curMatId >= _mats.Length)
        {
            _curMatId = 0;
        }

        _img.material = _mats[_curMatId];
    }

    public void PlayBlink()
    {
        if (_blinkCoroutine != null)
        {
            StopCoroutine(_blinkCoroutine);
            _blinkCoroutine = null;
        }

        _blinkCoroutine = BlinkCoroutine();
        StartCoroutine(_blinkCoroutine);
    }

    IEnumerator BlinkCoroutine()
    {
        SetValue(_data[0].Value);
        for (int i = 0; i < _data.Length - 1; i++)
        {
            var begin = _data[i].Value;
            var end = _data[i + 1].Value;
            var duration = _data[i].Duration;
            var timer = 0f;
            while (timer < duration)
            {
                SetValue(Mathf.Lerp(begin, end, timer / duration));
                timer += Time.deltaTime;
                yield return null;
            }
            SetValue(end);
        }
    }

    public void SetValue(float y)
    {
        if (_curMatId == 0)
        {
            _img.material.SetVector("_Param", new Vector4(0.6f, y, 1, 1));
        }
        else if (_curMatId == 1)
        {
            _img.material.SetFloat("_Height", y);
        }
    }


    private void Update() 
    {
        if (Input.GetKeyDown(KeyCode.Q))
        {
            ChangeMat();
        }
        if (Input.GetKeyDown(KeyCode.Space))
        {
            PlayBlink();
        }
    }

    [System.Serializable]
    private class BlinkData
    {
        public float Value;
        public float Duration;
    }
}