Æliens

  
  kernel NewFilter
  <  namespace : "Tunnel";
    vendor : "Mr.doob";
    version : 1;
    description : "Tunnel effect";
  >
  

  {
    input image4 src;
    output pixel4 dst;
    
    parameter float2 imgSize
    <
      defaultValue : float2(512.0, 512.0);
      minValue : float2(0.0,0.0);
      maxValue : float2(512.0,512.0);
    >;
  

    
    parameter float2 center
    <
      defaultValue : float2(256.0, 256.0);
      minValue : float2(0.0,0.0);
      maxValue : float2(512.0,512.0);    
    >;
    
    parameter float2 offset;
  
  

  
    void evaluatePixel()
    {    
      float2 pos = (outCoord() - center) / imgSize;
  
      float pi = 3.141592653589793;
      float a = atan(pos.y,pos.x);
      float r = sqrt(pow(pos.x,2.0)+pow(pos.y,2.0));
      
      float u = 0.0;
      float v = 0.0;
      float w = 0.0;
  
  

      
      u += offset.x;
      v += offset.y;
      
      u += 1.0/r;
      v += 3.0*a/pi;
      w += r*2.0;
  
      u *= imgSize.x;
      v *= imgSize.y;
  
  

      
      if (u < 0.0) u += imgSize.x * ceil(-u / imgSize.x);
      if (v < 0.0) v += imgSize.y * ceil(-v / imgSize.y);
      if (u > imgSize.x) u -= imgSize.x * floor(u / imgSize.x);
      if (v > imgSize.y) v -= imgSize.y * floor(v / imgSize.y);
      
      dst = sampleNearest(src,float2(u, v));
      dst.rgb *= w;
    }
  }