downsample_ps20.fxc

hl2 source code. Do not use it illegal.

#include "common_hdr.h"

sampler TexSampler	: register( s0 );

struct PS_INPUT
{
	float2 coordTap0				: TEXCOORD0;
	float2 coordTap1				: TEXCOORD1;
	float2 coordTap2				: TEXCOORD2;
	float2 coordTap3				: TEXCOORD3;
};

float lumThresh : register( c0 );

float4 main( PS_INPUT i ) : COLOR
{
	float4 s0, s1, s2, s3;

	// Sample 4 taps
	s0 = tex2D( TexSampler, i.coordTap0 );
	s1 = tex2D( TexSampler, i.coordTap1 );
	s2 = tex2D( TexSampler, i.coordTap2 );
	s3 = tex2D( TexSampler, i.coordTap3 );

#if 0
	// Apply threshold
	float4 v;
	if( s0.a < lumThresh )
		v[0] = 0.0f;
	else
		v[0] = s0.a;
	if( s1.a < lumThresh )
		v[1] = 0.0f;
	else
		v[1] = s1.a;
	if( s2.a < lumThresh )
		v[2] = 0.0f;
	else
		v[2] = s2.a;
	if( s3.a < lumThresh )
		v[3] = 0.0f;
	else
		v[3] = s3.a;
#endif

	s0.a = max( 0.0f, s0.a - 16.0f / 255.0f );
	s1.a = max( 0.0f, s1.a - 16.0f / 255.0f );
	s2.a = max( 0.0f, s2.a - 16.0f / 255.0f );
	s3.a = max( 0.0f, s3.a - 16.0f / 255.0f );

	float4 avgColor = ( s0 + s1 + s2 + s3 ) * 0.25f;
//	float avgLum = dot( v, 0.25f );

//	return float4( avgColor, avgLum );
	return avgColor;
}