#include "common.h"

struct 	v2p
{
  float4 tc0: 		TEXCOORD0;	// Central
  float4 tc1: 		TEXCOORD1;	// -1,+1
  float4 tc2: 		TEXCOORD2;	// -2,+2
  float4 tc3: 		TEXCOORD3;	// -3,+3
  float4 tc4: 		TEXCOORD4;	// -4,+4
  float4 tc5: 		TEXCOORD5;	// -5,+5
  float4 tc6: 		TEXCOORD6;	// -6,+6
  float4 tc7: 		TEXCOORD7;	// -7,+7
};

//////////////////////////////////////////////////////////////////////////////////////////
//	perform 4x4 bilinear, 8x8p, the step (B)
//	b):	64x64p	=> 8x8p
#ifdef  FP16_FILTER
	// native bilinear
half	sample	(half2	tc)	{
	return 	dot	(tex2D(s_image,tc), 1/4.h);	// sum components
}
#else
	// emulate bilinear
half	sample	(half2	tc)	{
	half 	phalf 	= .5h/64.h;
	half4 	res;
		res.x 	= dot	(tex2D(s_image,tc+half2(-phalf,-phalf)), 1/4.h); // sum components
		res.y 	= dot	(tex2D(s_image,tc+half2(+phalf,-phalf)), 1/4.h); // sum components
		res.z 	= dot	(tex2D(s_image,tc+half2(-phalf,+phalf)), 1/4.h); // sum components
		res.w 	= dot	(tex2D(s_image,tc+half2(+phalf,+phalf)), 1/4.h); // sum components
	return 	dot	(res, 	1/4.h);	// sum components
}
#endif

half4 	main		( v2p I )	: COLOR
{
	// sample
	half4 	accum0;
		accum0.x =	sample(I.tc0);
		accum0.y = 	sample(I.tc1);
		accum0.z = 	sample(I.tc2);
		accum0.w =	sample(I.tc3);
	half4 	accum1;
		accum1.x =	sample(I.tc4);
		accum1.y = 	sample(I.tc5);
		accum1.z = 	sample(I.tc6);
		accum1.w =	sample(I.tc7);
	half4 	accum2;
		accum2.x =	sample(I.tc0.wz);
		accum2.y = 	sample(I.tc1.wz);
		accum2.z = 	sample(I.tc2.wz);
		accum2.w =	sample(I.tc3.wz);
	half4 	accum3;
		accum3.x =	sample(I.tc4.wz);
		accum3.y = 	sample(I.tc5.wz);
		accum3.z = 	sample(I.tc6.wz);
		accum3.w =	sample(I.tc7.wz);

	// perform accumulation
	half4	final;
		final.x	= dot(accum0,1/4.h);
		final.y	= dot(accum1,1/4.h);
		final.z	= dot(accum2,1/4.h);
		final.w	= dot(accum3,1/4.h);

	// OK
	return 	final;
}