android开发分享OpenGL Shader实例分析（3）等待标识效果

  shader "stalendp/waiticons" {     cginclude          #include "unitycg.cginc"         #pragma target 3.0      struct v2f {       float4 pos:sv_position;       float2 uv : texcoord0;      };          v2f vert(appdata_base v) {       v2f o;      o.pos = mul (unity_matrix_mvp, v.vertex);      o.uv = v.texcoord.xy;      return o;      }          fixed calcdot(fixed a, fixed ca, fixed2 uv) {     a /= 57.295779513;     ca /= 57.295779513;     fixed tt = 180/57.295779513;     uv = (fixed2(cos(a), sin(a)) * 0.2+ uv)*10;     fixed adit = tt*2*step(tt, a-ca);     fixed r = 1-step(ca + adit, a);     r *= lerp(0.2, -1, saturate((ca-a+adit)/25))*2;     return smoothstep(r-0.2, r, length(uv.xy));    }        fixed4 frag(v2f input) : color0 {       float2 uv = input.uv.xy - float2(0.5);      float rx = fmod(uv.x, 0.4);      float ry = fmod(uv.y, 0.4);      float mx = step(0.4, abs(uv.x));      float my = step(0.4, abs(uv.y));      float alpha = 1- mx*my*step(0.1, length(half2(rx,ry)));      alpha*=0.9;           fixed4 forecolor = fixed4(1);     fixed4 bgcolor = fixed4(fixed3(0.4),alpha);     fixed4 result = bgcolor;          fixed ca = fmod(_time.y, 2)*180;        bgcolor = lerp(forecolor, bgcolor, calcdot(0, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(30, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(60, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(90, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(120, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(150, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(180, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(210, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(240, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(270, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(300, ca, uv));   bgcolor = lerp(forecolor, bgcolor, calcdot(330, ca, uv));          return bgcolor;     }     endcg         subshader {      lod 200     tags {"queue" = "transparent"}     zwrite off     blend srcalpha oneminussrcalpha      pass {       cgprogram           #pragma vertex vert       #pragma fragment frag       #pragma fragmentoption arb_precision_hint_fastest            endcg      }         }      fallback off    }