#define SAMPLE_SIZE 9

uniform vec4 OGL2Param;
uniform vec4 OGL2Size;
uniform sampler2D OGL2Texture;

const mat3 rgbTOyiq = mat3(
   0.299, 0.587, 0.114,
   .596, -.274, -.322,
   .211, -.523, .312
);

const mat3 yiqTOrgb = mat3(
   1.0, .956, .621,
   1.0, -.272, -.647,
   1.0, -1.106, 1.703
);

vec2 maskPos[9];
float filter[9];

void init();


void main(void)
{
   vec4 texColor;
   vec4 original;
   float fk = (OGL2Param.z + 1.0) * 0.25;
   
   init();
   
   original = texture2D(OGL2Texture, gl_TexCoord[0].xy + maskPos[4]);
   
   for(int i=0; i < SAMPLE_SIZE; i++)
   {
      vec4 tmp = texture2D(OGL2Texture, gl_TexCoord[0].xy + maskPos[i]);
      texColor.x += vec3(rgbTOyiq * tmp.xyz).x;
   }
   
   texColor.x -= original.x * filter[4];
   texColor.x *= OGL2Param.z*0.05;

   gl_FragColor = vec4(yiqTOrgb * texColor.xyz, 0.0);
}


void init()
{
   float stepX = 1.0 / OGL2Size.x;
   float stepY = 1.0 / OGL2Size.y;
   
   maskPos[0] = vec2(-stepX, stepY);
   maskPos[1] = vec2(0.0, stepY);
   maskPos[2] = vec2(stepX, stepY);
   maskPos[3] = vec2(-stepX, 0.0);
   maskPos[4] = vec2(0.0, 0.0);
   maskPos[5] = vec2(stepX, 0.0);
   maskPos[6] = vec2(-stepX, -stepY);
   maskPos[7] = vec2(0.0, -stepY);
   maskPos[8] = vec2(stepX, -stepY);
   
   filter[0] = 0.0;
   filter[1] = 0.0;
   filter[2] = 0.0;
   filter[3] = 0.0;
   filter[4] = 0.2;
   filter[5] = 0.0;
   filter[6] = 0.0;
   filter[7] = 0.0;
   filter[8] = 0.0;
}