【Unity3D Shader】实现流光效果

流光效果图：

演示工程：下载地址

//功能需求：模拟数据传送效果，高亮色块从模型上方移动到下方
//功能分析：这里采用UV动画的方式来实现，利用Alpha贴图控制流动的形状
//          利用Alpha遮罩贴图，控制模型中哪些地方需要进行流动

Shader "Custom/DataFlowEffect"
{
    Properties
    {
        _MainColor("Main Color",Color) = (1,1,1,1)
        _MainTex("Main Texture",2D) = "white"{}
        _Specular("Specular",Color) = (1,1,1,1)
        _Gloss("Gloss",Range(0,255)) = 20.0
        _FlowTex("Flow Tex (A)",2D) = "black"{}
        _FlowColor("Flow Color (RGBA)",Color)=(1,1,1,1)
        _FlowIdleTime("FlowInternal",Range(0,10))=1.0
        _FlowDuring("FlowDuring",Range(0,10))=1.0
        _FlowMaskTex("FlowMasking (A)",2D)="white"{}
        _FlowDirection("FlowDirection",Int)= 0
        _FlowBeginTime("Flow Begin Time",Float)=0
    }

    SubShader
    {
        Tags{"RenderType" = "Opaque" "Queue"="Geometry"}

        Pass
        {
            Tags{"LightMode"="ForwardBase"}
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"
            #include "Lighting.cginc"

            sampler2D _MainTex;     //颜色贴图
            half4 _MainTex_ST;      //颜色UV 缩放和偏移
            fixed3 _MainColor;      //漫反射颜色
            fixed3 _Specular;       //高光颜色
            fixed _Gloss;           //高光度
            sampler2D _FlowTex;     //数据流图片
            fixed4 _FlowColor;      //数据流颜色叠加
            half4 _FlowTex_ST;      //数据流贴图UV的缩放和偏移
            fixed _FlowIdleTime;    //流动动画间歇时间
            fixed _FlowDuring;      //流动动画播放时间
            sampler2D _FlowMaskTex; //流动遮罩
            fixed _FlowDirection;   //流动方向
            float _FlowBeginTime;   //流动效果开始的时间

            struct a2v
            {
                half4 pos: POSITION;
                half3 normal :NORMAL;
                half4 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                half4 position : SV_POSITION;
                half2 uv : TEXCOORD0;
                half3 worldNormal : TEXCOORD1;
                half3 worldPos : TEXCOORD2;
                half2 flowUV : TEXCOORD3;
            };

            v2f vert(a2v i)
            {
                v2f v;
                v.position = UnityObjectToClipPos(i.pos);
                v.uv = i.texcoord * _MainTex_ST.xy + _MainTex_ST.zw;
                v.worldNormal = mul(unity_ObjectToWorld,i.normal);
                v.worldPos = mul(unity_ObjectToWorld,i.pos);
                v.flowUV = i.texcoord * _FlowTex_ST.xy + _FlowTex_ST.zw;
                return v;
            }

            //uv - vert的uv坐标
            //scale - 贴图缩放
            //idleTime - 每次循环开始后多长时间，开始流动
            //loopTime - 单次流动时间
            fixed4 getFlowColor(half2 uv,int scale,fixed idleTime,fixed loopTime)
            {
                //当前运行时间
                half flowTime_ = _Time.y - _FlowBeginTime;

                //上一次循环开始，到本次循环开始的时间间隔
                half internal = idleTime + loopTime;

                //当前循环执行时间
                half curLoopTime = fmod(flowTime_,internal);

                //每次开始流动之前，有个停止间隔，检测是否可以流动了
                if(curLoopTime > idleTime)
                {
                    //已经流动时间
                    half actionTime = curLoopTime - idleTime;

                    //流动进度百分比
                    half actionPercentage = actionTime / loopTime;

                    half length = 1.0 / scale;

                    //从下往上流动
                    //计算方式：设：y = ax + b，其中y为下边界值，x为流动进度
                    //根据我们要求可以，x=0时y=-length；x=1时y=1；带入解方程
                    half bottomBorder = actionPercentage * (1+length) - length;
                    half topBorder = bottomBorder + length;

                    //从上往下流动
                    //求解方法与上面类似
                    if(_FlowDirection < 0)
                    {
                        topBorder = (-1-length) * actionPercentage + 1 + length;
                        bottomBorder = topBorder - length;
                    }

                    if(uv.y < topBorder && uv.y > bottomBorder)
                    {
                        half y = (uv.y - bottomBorder) / length;
                        return tex2D(_FlowTex,fixed2(uv.x,y)); 
                    }
                }

                return fixed4(1,1,1,0);
            }

            fixed4 frag(v2f v):SV_Target
            {
                //计算漫反射系数
                fixed3 albedo = tex2D(_MainTex,v.uv) * _MainColor;

                //计算环境光
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;


                fixed3 worldNormal = normalize(v.worldNormal);                              //世界坐标的法线方向
                fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(v.worldPos));      //世界坐标的光照方向
                fixed3 worldViewDir = normalize(UnityWorldSpaceViewDir(v.worldPos));        //世界坐标的视角方向

                //计算漫反射颜色,采用Half-Lambert模型
                fixed3 lightColor = _LightColor0.rgb;
                fixed3 diffuse = lightColor * albedo * max(0,0.5*dot(worldNormal,worldLightDir)+0.5);

                //计算高光,采用Blinn-Phone高光模型
                fixed3 halfDir = normalize(worldViewDir + worldLightDir);
                fixed3 specColor = _Specular * lightColor * pow(max(0,dot(worldNormal,halfDir)),_Gloss);

                //叠加流动贴图                
                fixed4 flowColor = getFlowColor(v.uv,_FlowTex_ST.y,_FlowIdleTime,_FlowDuring);  
                fixed4 flowMaskColor = tex2D(_FlowMaskTex,v.uv);

                //与遮罩贴图进行混合，只显示遮罩贴图不透明的部分
                flowColor.a = flowMaskColor.a * flowColor.a * _FlowColor.a;

                fixed3 finalDiffuse = lerp(diffuse,_FlowColor,flowColor.a);

                return fixed4(ambient + finalDiffuse+specColor,1);
            }

            ENDCG
        }
    }
    Fallback "Diffuse"
}