LogoShader 使logo模型呈现光影快速穿过的特效

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Custom/LogoShader" {
    Properties{
        _MainTex("Texture", 2D) = "white" { }
    }
        SubShader
    {
    Tags {"Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent"}
    Blend SrcAlpha OneMinusSrcAlpha
        AlphaTest Greater 0.1
        pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            sampler2D _MainTex;
            float4 _MainTex_ST;

            struct v2f {
                float4  pos : SV_POSITION;
                float2  uv : TEXCOORD0;
            };

            v2f vert(appdata_base v)
            {
                v2f o;
                   o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.texcoord,_MainTex);
                return o;
            }

            float inFlash(float angle,float2 uv,float xLength,int interval,int beginTime, float offX, float loopTime)
            {
                float brightness = 0;

                float angleInRad = 0.0174444 * angle;//斜角

                float currentTime = _Time.y;

                int currentTimeInt = _Time.y / interval;
                currentTimeInt *= interval;

                float currentTimePassed = currentTime - currentTimeInt;

                if (currentTimePassed > beginTime)
                {
                    float xBottomLeftBound;
                    float xBottomRightBound;

                    float xPointLeftBound;
                    float xPointRightBound;

                    float x0 = currentTimePassed - beginTime;
                    x0 /= loopTime;

                    xBottomRightBound = x0;

                    xBottomLeftBound = x0 - xLength;

                    float xProjL;
                    xProjL = (uv.y) / tan(angleInRad);

                    xPointLeftBound = xBottomLeftBound - xProjL;
                    xPointRightBound = xBottomRightBound - xProjL;

                    xPointLeftBound += offX;
                    xPointRightBound += offX;

                    if (uv.x > xPointLeftBound && uv.x < xPointRightBound)
                    {
                        float midness = (xPointLeftBound + xPointRightBound) / 2;

                        float rate = (xLength - 2 * abs(uv.x - midness)) / (xLength) * 10;//光照强度
                        brightness = rate;
                    }
                }
                brightness = max(brightness,0);

                float4 col = float4(1,1,1,1) *brightness;
                return brightness;
            }

            float4 frag(v2f i) : COLOR
            {
                 float4 outp;

                float4 texCol = tex2D(_MainTex,i.uv);

                float tmpBrightness;
                tmpBrightness = inFlash(75,i.uv, 0.2f,3,0,0.15f,3.0f);// float angle, float2 uv, float xLength, int interval, int beginTime, float offX, float loopTime

                if (texCol.w > 0.5)
                        outp = texCol + float4(1,1,1,1)*tmpBrightness;
                else
                    outp = float4(0,0,0,0);

                return outp;
            }
            ENDCG
        }
    }
}