UnityShader如何實(shí)現新手引導遮罩鏤空效果

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1、圓形鏤空shader代碼：

//計算片元世界坐標和目標中心位置的距離float dis = distance(IN.worldPosition.xy, _Center.xy);//過(guò)濾掉距離小于（半徑-過(guò)渡范圍）的片元clip(dis - (_Radius - _TransitionRange));//優(yōu)化if條件判斷，如果距離小于半徑則執行下一步，等于if(dis < _Radius)fixed tmp = step(dis, _Radius);//計算過(guò)渡范圍內的alpha值color.a *= (1 - tmp) + tmp * (dis - (_Radius - _TransitionRange)) / _TransitionRange;

效果：忽略漸變的蒙版，隨便找的圖片

2、橢圓鏤空shader代碼：

//計算X軸方向距離float disX = distance(IN.worldPosition.x, _Center.x);//計算Y軸方向距離float disY = distance(IN.worldPosition.y, _Center.y);//運用橢圓方程計算片元的alpha值，_Ellipse為橢圓系數fixed factor = clamp(pow(abs(disX / _Width), _Ellipse) + pow(abs(disY / _Height), _Ellipse), 0.0, 1.0);//優(yōu)化if條件判斷fixed tmp = step(factor, 1.0f);//賦值橢圓外或橢圓內的alpha值color.a *= (1 - tmp) + tmp * factor;

效果：

3、圓形目標位置聚合動(dòng)畫(huà)shader代碼：

//_StartTime為效果開(kāi)始時(shí)間點(diǎn)，Unity中對應賦值material.SetFloat("_StartTime", Time.timeSinceLevelLoad);fixed processTime = _Time.y - _StartTime;//判斷shader執行時(shí)長(cháng)是否超過(guò)_TotalTimeclip(_TotalTime - processTime);//優(yōu)化if條件判斷fixed tmp = step(processTime, _ReduceTime);//計算當前時(shí)間點(diǎn)的圓形鏤空半徑float curRadius = (1 - tmp) * _Radius + tmp * (_MaxRadius - (_MaxRadius - _Radius) * processTime / _ReduceTime);float dis = distance(IN.worldPosition.xy, _Center.xy);//拋棄距離小于當前圓形鏤空半徑的片元clip(dis - curRadius);

效果：不知道為啥上傳上來(lái)就有問(wèn)題了，正常是沒(méi)問(wèn)題的

整個(gè)shader源碼，在Unity UGUI 自帶Default shader基礎上添加：

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)Shader "UI/Default_Mask"{  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 //-------------------add---------------------- _Center("Center", vector) = (0, 0, 0, 0) _Radius("Radius", Range(0,1000)) = 1000 // sliders _TransitionRange("Transition Range", Range(0, 100)) = 10 _Width("Width", Float) = 1 _Height("Height", Float) = 1 _Ellipse("Ellipse", Float) = 4 _ReduceTime("ReduceTime", Float) = 1 _TotalTime("TotalTime", Float) = 1 _StartTime("StartTime", Float) = 0 _MaxRadius("MaxRadius", Float) = 1500 [KeywordEnum(ROUND, ELLIPSE, DYNAMIC_ROUND)] _RoundMode("Mask mode", Float) = 0 //-------------------add----------------------  }  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  #pragma multi_compile _ROUNDMODE_ROUND _ROUNDMODE_ELLIPSE _ROUNDMODE_DYNAMIC_ROUND      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      };      fixed4 _Color;      fixed4 _TextureSampleAdd;      float4 _ClipRect;  //-------------------add----------------------  half _Radius;  float2 _Center;  half _TransitionRange;  half _Width;  half _Height;  half _Ellipse;  fixed _ReduceTime;  half _TotalTime;  float _StartTime;  half _MaxRadius;  //-------------------add----------------------      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 = v.texcoord;        OUT.color = v.color * _Color;        return OUT;      }      sampler2D _MainTex;      fixed4 frag(v2f IN) : SV_Target      {        half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;        #ifdef UNITY_UI_CLIP_RECT        color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);        #endif        #ifdef UNITY_UI_ALPHACLIP        clip (color.a - 0.001);        #endif  //-------------------add----------------------#ifdef _ROUNDMODE_ROUND  //計算片元世界坐標和目標中心位置的距離  float dis = distance(IN.worldPosition.xy, _Center.xy);  //過(guò)濾掉距離小于（半徑-過(guò)渡范圍）的片元  clip(dis - (_Radius - _TransitionRange));  //優(yōu)化if條件判斷，如果距離小于半徑則執行下一步，等于if(dis < _Radius)  fixed tmp = step(dis, _Radius);  //計算過(guò)渡范圍內的alpha值  color.a *= (1 - tmp) + tmp * (dis - (_Radius - _TransitionRange)) / _TransitionRange;#elif _ROUNDMODE_ELLIPSE  //計算X軸方向距離  float disX = distance(IN.worldPosition.x, _Center.x);  //計算Y軸方向距離  float disY = distance(IN.worldPosition.y, _Center.y);  //運用橢圓方程計算片元的alpha值，_Ellipse為橢圓系數  fixed factor = clamp(pow(abs(disX / _Width), _Ellipse) + pow(abs(disY / _Height), _Ellipse), 0.0, 1.0);  //優(yōu)化if條件判斷  fixed tmp = step(factor, 1.0f);  //賦值橢圓外或橢圓內的alpha值  color.a *= (1 - tmp) + tmp * factor;#else  //_StartTime為效果開(kāi)始時(shí)間點(diǎn)，Unity中對應賦值material.SetFloat("_StartTime", Time.timeSinceLevelLoad);  fixed processTime = _Time.y - _StartTime;  //判斷shader執行時(shí)長(cháng)是否超過(guò)_TotalTime  clip(_TotalTime - processTime);  //優(yōu)化if條件判斷  fixed tmp = step(processTime, _ReduceTime);  //計算當前時(shí)間點(diǎn)的圓形鏤空半徑  float curRadius = (1 - tmp) * _Radius + tmp * (_MaxRadius - (_MaxRadius - _Radius) * processTime / _ReduceTime);  float dis = distance(IN.worldPosition.xy, _Center.xy);  //拋棄距離小于當前圓形鏤空半徑的片元  clip(dis - curRadius);#endif  //-------------------add----------------------        return color;      }    ENDCG    }  }}