Unity3D实现老电视花屏闪烁效果

Shader "Custom/Screen" ｛  
    Properties｛  
        _MainTex("贴图", 2D) = "white" ｛｝  
        _TimeScale("花屏速度" , Range(0.0001, 2.0)) = 1.0  
    ｝  
        SubShader｛  
        Tags｛ "RenderType" = "Opaque" ｝  
        LOD 300  
        pass ｛  
        Cull Back  
            CGPROGRAM  
        #pragma vertex vert  
        #pragma fragment frag  
        #include "UnityCG.cginc"  
        #define R frac(43.*sin(p.x*73.+p.y*8.))  
        float _TimeScale;  
        float sat(float t) ｛  
            return clamp(t, 0.0, 1.0);  
        ｝  
        float2 sat(float2 t) ｛  
            return clamp(t, 0.0, 1.0);  
        ｝  
        float remap(float t, float a, float b) ｛  
            return sat((t - a) / (b - a));  
        ｝  
        float linterp(float t) ｛  
            return sat(1.0 - abs(2.0*t - 1.0));  
        ｝  
        float3 spectrum_offset(float t) ｛  
            float3 ret;  
            float lo = step(t,0.5);  
            float hi = 1.0 - lo;  
            float w = linterp(remap(t, 1.0 / 6.0, 5.0 / 6.0));  
            float neg_w = 1.0 - w;  
            ret = float3(lo,1.0,hi) * float3(neg_w, w, neg_w);  
            return pow(ret, float3(1.0 / 2.2, 1.0 / 2.2, 1.0 / 2.2));  
        ｝  
        float rand(float2 n) ｛  
            return (sin(dot(float2(n.x *_TimeScale, n.y *_TimeScale), float2(12.9898, 78.233))));  
        ｝  
        float srand(float2 n) ｛  
            return rand(n) * 2.0 - 1.0;  
        ｝  
        float mytrunc(float x, float num_levels)  
        ｛  
            return floor(x*num_levels) / num_levels;  
        ｝  
        float2 mytrunc(float2 x, float num_levels)  
        ｛  
            return floor(x*num_levels) / num_levels;  
        ｝  
            sampler2D _MainTex;  
        float4 _MainTex_ST;  
        float uvOffset;  
        struct a2v ｛  
            float4 vertex : POSITION;  
            float3 normal : NORMAL;  
            float4 texcoord : TEXCOORD0;  
        ｝;  
        struct v2f ｛  
            float4 pos : POSITION;  
            float2 uv : TEXCOORD0;  
            float3 color : TEXCOORD1;  
        ｝;  
        v2f vert(a2v v) ｛  
            v2f o; o.pos = UnityObjectToClipPos(v.vertex);  
            o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);  
            o.color = ShadeVertexLights(v.vertex, v.normal);  
            return o;  
        ｝  
        float4 frag(v2f i) : COLOR｛  
        float4 c;  
        float aspect = _ScreenParams.x / _ScreenParams.y;  
        aspect = 1;  
        float2 uv = _ScreenParams.xy / _ScreenParams.xy;  
        uv = float2(1,1);  
        float time = fmod(_Time.y, 32.0);   
        float GLITCH = 10.1;  
        float gnm = sat(GLITCH);  
        float rnd0 = rand(mytrunc(float2(time, time), 6.0));  
        float r0 = sat((1.0 - gnm)*0.7 + rnd0);  
        float rnd1 = rand(float2(mytrunc(i.uv.x, 10.0*r0), time));  
        float r1 = 0.5 - 0.5 * gnm + rnd1;  
        r1 = 1.0 - max(0.0, ((r1<1.0) ? r1 : 0.9999999));  
        float rnd2 = rand(float2(mytrunc(i.uv.y, 40.0*r1), time));   
        float r2 = sat(rnd2);  
        float rnd3 = rand(float2(mytrunc(i.uv.y, 10.0*r0), time));  
        float r3 = (1.0 - sat(rnd3 + 0.8)) - 0.1;  
        float pxrnd = rand(i.uv + time);  
        float ofs = 0.05 * r2 * GLITCH * (rnd0 > 0.5 ? 1.0 : -1.0);  
        ofs += 0.5 * pxrnd * ofs;  
        i.uv.y += 0.1 * r3 * GLITCH;  
        const int NUM_SAMPLES = 10;  
        const float RCP_NUM_SAMPLES_F = 1.0 / float(NUM_SAMPLES);  
        float4 sum = float4(0.0, 0.0, 0.0, 0.0);  
        float3 wsum = float3(0.0, 0.0, 0.0);  
        for (int j = 0; j<NUM_SAMPLES; ++j)  
        ｛  
            float t = float(j) * RCP_NUM_SAMPLES_F;  
            i.uv.x = sat(i.uv.x + ofs * t);  
            float4 samplecol = tex2D(_MainTex, i.uv);   
            float3 s = spectrum_offset(t);  
            samplecol.rgb = samplecol.rgb * s;  
            sum += samplecol;  
            wsum += s;  
        ｝  
        sum.rgb /= wsum;  
        sum.a *= RCP_NUM_SAMPLES_F;  
        c.a = sum.a;  
        c.rgb = sum.rgb;  
        c.rgb = c.rgb;  
        return c;  
        ｝  
            ENDCG  
    ｝  
    ｝FallBack "Diffuse"  
｝