struct tex_coords
{
   float2 c00 : TEXCOORD0;
   float2 c01 : TEXCOORD1; 
   float2 c02 : TEXCOORD2;
   float2 c10 : TEXCOORD3;
   float2 c11 : TEXCOORD4; 
   float2 c12 : TEXCOORD5; 
   float2 c20 : TEXCOORD6;
   float2 c21 : TEXCOORD7; 
   float2 c22 : COLOR0;
};

struct input
{
   float2 video_size;
   float2 texture_size;
   float2 output_size;
};

void main_vertex
(
   float4 position	: POSITION,
   out float4 oPosition : POSITION,
   uniform float4x4 modelViewProj,

   float2 tex : TEXCOORD,

   uniform input IN,
   out tex_coords coords
)
{
   oPosition = mul(modelViewProj, position);

   float2 texsize = IN.texture_size;
   float2 delta = 0.5 / texsize;
   float dx = delta.x;
   float dy = delta.y;

   coords = tex_coords (
      tex + float2(-dx, -dy),
      tex + float2(-dx, 0),
      tex + float2(-dx, dy),
      tex + float2(0, -dy),
      tex + float2(0, 0),
      tex + float2(0, dy),
      tex + float2(dx, -dy),
      tex + float2(dx, 0),
      tex + float2(dx, dy)
   );
}

const float mx = 0.325;      // start smoothing wt.
const float k = -0.250;      // wt. decrease factor
const float max_w = 0.25;    // max filter weigth
const float min_w = -0.05;    // min filter weigth
const float lum_add = 0.25;  // effects smoothing

float4 main_fragment (in tex_coords co, uniform sampler2D s_p : TEXUNIT0) : COLOR
{
   float3 c00 = tex2D(s_p, co.c00).xyz;
   float3 c01 = tex2D(s_p, co.c01).xyz;
   float3 c02 = tex2D(s_p, co.c02).xyz;
   float3 c10 = tex2D(s_p, co.c10).xyz;
   float3 c11 = tex2D(s_p, co.c11).xyz;
   float3 c12 = tex2D(s_p, co.c12).xyz;
   float3 c20 = tex2D(s_p, co.c20).xyz;
   float3 c21 = tex2D(s_p, co.c21).xyz;
   float3 c22 = tex2D(s_p, co.c22).xyz;
   float3 dt = float3(1.0);

   float md1 = dot(abs(c00 - c22), dt);
   float md2 = dot(abs(c02 - c20), dt);

   float w1 = dot(abs(c22 - c11), dt) * md2;
   float w2 = dot(abs(c02 - c11), dt) * md1;
   float w3 = dot(abs(c00 - c11), dt) * md2;
   float w4 = dot(abs(c20 - c11), dt) * md1;

   float t1 = w1 + w3;
   float t2 = w2 + w4;
   float ww = max(t1, t2) + 0.0001;

   c11 = (w1 * c00 + w2 * c20 + w3 * c22 + w4 * c02 + ww * c11) / (t1 + t2 + ww);

   float lc1 = k / (0.12 * dot(c10 + c12 + c11, dt) + lum_add);
   float lc2 = k / (0.12 * dot(c01 + c21 + c11, dt) + lum_add);

   w1 = clamp(lc1 * dot(abs(c11 - c10), dt) + mx, min_w, max_w);
   w2 = clamp(lc2 * dot(abs(c11 - c21), dt) + mx, min_w, max_w);
   w3 = clamp(lc1 * dot(abs(c11 - c12), dt) + mx, min_w, max_w);
   w4 = clamp(lc2 * dot(abs(c11 - c01), dt) + mx, min_w, max_w);

   return float4(w1 * c10 + w2 * c21 + w3 * c12 + w4 * c01 + (1.0 - w1 - w2 - w3 - w4) * c11, 1.0);
}
