Shader开发-LOGO闪光效果

hader "Custom/LeiChaoOne" {
        Properties{
            _MainTex("Texture", 2D) = "white" { }
        }
            SubShader
        {
            AlphaTest Greater .2
            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;
            };

            //顶点函数没什么特别的，和常规一样
            v2f vert(appdata_base v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.texcoord,_MainTex);
                return o;
            }

            //必须放在使用其的 frag函数之前，否则无法识别。
            //核心：计算函数，角度，uv,光带的x长度，间隔，开始时间，偏移，单次循环时间
            float inFlash(float angle,float2 uv,float xLength,int interval,int beginTime, float offX, float loopTime)
            {
                //亮度值
                float brightness = 0;

                //倾斜角
             // float angleInRad = 0.0174444 * angle;
                float angleInRad = 0.005 * angle;
                //当前时间
                float currentTime = _Time.y;

                //获取本次光照的起始时间
                int currentTimeInt = _Time.y / interval;
                currentTimeInt *= interval;

                //获取本次光照的流逝时间 = 当前时间 - 起始时间
                float currentTimePassed = currentTime - currentTimeInt;
                if (currentTimePassed >beginTime)
                {
                    //底部左边界和右边界
                    float xBottomLeftBound;
                    float xBottomRightBound;

                    //此点边界
                    float xPointLeftBound;
                    float xPointRightBound;

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

                    //设置右边界
                    xBottomRightBound = x0;

                    //设置左边界
                    xBottomLeftBound = x0 - xLength;

                    //投影至x的长度 = y/ tan(angle)
                    float xProjL;
                    xProjL = (uv.y) / tan(angleInRad);

                    //此点的左边界 = 底部左边界 - 投影至x的长度
                    xPointLeftBound = xBottomLeftBound - xProjL;
                    //此点的右边界 = 底部右边界 - 投影至x的长度
                    xPointRightBound = xBottomRightBound - xProjL;

                    //边界加上一个偏移
                    xPointLeftBound += offX;
                    xPointRightBound += offX;

                    //如果该点在区域内
                    if (uv.x > xPointLeftBound && uv.x < xPointRightBound)
                    {
                        //得到发光区域的中心点
                        float midness = (xPointLeftBound + xPointRightBound) / 2;

                        //趋近中心点的程度，0表示位于边缘，1表示位于中心点
                        float rate = (xLength - 2 * abs(uv.x - midness)) / (xLength);
                        brightness = rate;
                    }
                }
                brightness = max(brightness,0);

                //返回颜色 = 纯白色 * 亮度
                float4 col = float4(1,1,1,1) *brightness;
                return brightness;
            }

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

            //根据uv取得纹理颜色，和常规一样
            float4 texCol = tex2D(_MainTex,i.uv);

            //传进i.uv等参数，得到亮度值
            float tmpBrightness;
            tmpBrightness = inFlash(75,i.uv,0.25f,5.0f,2.0f,0.15f,0.7f);

            //图像区域，判定设置为颜色的A > 0.5,输出为材质颜色+光亮值
            if (texCol.w >0.5)
                outp = texCol + float4(1,1,1,1)*tmpBrightness;
            //空白区域，判定设置为颜色的A <=0.5,输出空白
            else
                outp = float4(0,0,0,0);

            return outp;
            }
                ENDCG
        }
    }
    FallBack "Diffuse"
}