sqwarmed/sdk_src/materialsystem/stdshaders/luminance_compare_ps2x.fxc

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//========== Copyright (c) Valve Corporation, All rights reserved. ==========//
#define HDRTYPE HDR_TYPE_NONE
#include "common_ps_fxc.h"
// This pixel shader compares the luminance against a constant value and retruns all 1's when greater
sampler TexSampler : register( s0 );
struct PS_INPUT
{
float2 uv0 : TEXCOORD0;
};
float3 g_vComparisonMinMaxScale : register( c0 );
#define g_flComparisonMin g_vComparisonMinMaxScale.x
#define g_flComparisonMax g_vComparisonMinMaxScale.y
struct PS_OUTPUT
{
float4 color : COLOR0;
#ifndef _X360
float depth : DEPTH; // Workaround for ATI driver bug
#endif
};
PS_OUTPUT main( PS_INPUT i )
{
float3 color = tex2D( TexSampler, i.uv0 );
// Formula for calculating luminance based on NTSC standard
float3 tmpv = { 0.2125f, 0.7154f, 0.0721f };
float flLuminance = dot( color.rgb, tmpv.rgb );
// Alternate formula for calculating luminance for linear RGB space (Widely used in color hue and saturation computations)
//float3 tmpv = { 0.3086f, 0.6094f, 0.0820f };
//float flLuminance = dot( color.rgb, tmpv.rgb );
// Simple average
//float flLuminance = ( color.r + color.g + color.b ) * 0.33333f;
PS_OUTPUT o;
o.color.rgba = step( g_flComparisonMin, flLuminance ) * step( flLuminance, g_flComparisonMax );
#ifndef _X360
{
o.depth = 0.0f; // Workaround for ATI driver bug
}
#endif
return o;
}