#ifndef GAMMA_MANAGEMENT_H
#define GAMMA_MANAGEMENT_H

/////////////////////////////////  MIT LICENSE  ////////////////////////////////

//  Copyright (C) 2014 TroggleMonkey
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to
//  deal in the Software without restriction, including without limitation the
//  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
//  sell copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//  
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
//  IN THE SOFTWARE.

/////////////////////////////////  DESCRIPTION  ////////////////////////////////

//  This file provides gamma-aware tex*D*() and encode_output() functions.
//  Requires:   Before #include-ing this file, the including file must #define
//              the following macros when applicable and follow their rules:
//              1.) #define FIRST_PASS if this is the first pass.
//              2.) #define LAST_PASS if this is the last pass.
//              3.) If sRGB is available, set srgb_framebufferN = "true" for
//                  every pass except the last in your .cgp preset.
//              4.) If sRGB isn't available but you want gamma-correctness with
//                  no banding, #define GAMMA_ENCODE_EVERY_FBO each pass.
//              5.) #define SIMULATE_CRT_ON_LCD if desired (precedence over 5-7)
//              6.) #define SIMULATE_GBA_ON_LCD if desired (precedence over 6-7)
//              7.) #define SIMULATE_LCD_ON_CRT if desired (precedence over 7)
//              8.) #define SIMULATE_GBA_ON_CRT if desired (precedence over -)
//              If an option in [5, 8] is #defined in the first or last pass, it
//              should be #defined for both.  It shouldn't make a difference
//              whether it's #defined for intermediate passes or not.
//  Optional:   The including file (or an earlier included file) may optionally
//              #define a number of macros indicating it will override certain
//              macros and associated constants are as follows:
//              static constants with either static or uniform constants.  The
//              1.) OVERRIDE_STANDARD_GAMMA: The user must first define:
//                  static const float ntsc_gamma
//                  static const float pal_gamma
//                  static const float crt_reference_gamma_high
//                  static const float crt_reference_gamma_low
//                  static const float lcd_reference_gamma
//                  static const float crt_office_gamma
//                  static const float lcd_office_gamma
//              2.) OVERRIDE_DEVICE_GAMMA: The user must first define:
//                  static const float crt_gamma
//                  static const float gba_gamma
//                  static const float lcd_gamma
//              3.) OVERRIDE_FINAL_GAMMA: The user must first define:
//                  static const float input_gamma
//                  static const float intermediate_gamma
//                  static const float output_gamma
//                  (intermediate_gamma is for GAMMA_ENCODE_EVERY_FBO.)
//              4.) OVERRIDE_ALPHA_ASSUMPTIONS: The user must first define:
//                  static const bool assume_opaque_alpha
//              The gamma constant overrides must be used in every pass or none,
//              and OVERRIDE_FINAL_GAMMA bypasses all of the SIMULATE* macros.
//              OVERRIDE_ALPHA_ASSUMPTIONS may be set on a per-pass basis.
//  Usage:      After setting macros appropriately, ignore gamma correction and
//              replace all tex*D*() calls with equivalent gamma-aware
//              tex*D*_linearize calls, except:
//              1.) When you read an LUT, use regular tex*D or a gamma-specified
//                  function, depending on its gamma encoding:
//                      tex*D*_linearize_gamma (takes a runtime gamma parameter)
//              2.) If you must read pass0's original input in a later pass, use
//                  tex2D_linearize_ntsc_gamma.  If you want to read pass0's
//                  input with gamma-corrected bilinear filtering, consider
//                  creating a first linearizing pass and reading from the input
//                  of pass1 later.
//              Then, return encode_output(color) from every fragment shader.
//              Finally, use the global gamma_aware_bilinear boolean if you want
//              to statically branch based on whether bilinear filtering is
//              gamma-correct or not (e.g. for placing Gaussian blur samples).
//
//  Detailed Policy:
//  tex*D*_linearize() functions enforce a consistent gamma-management policy
//  based on the FIRST_PASS and GAMMA_ENCODE_EVERY_FBO settings.  They assume
//  their input texture has the same encoding characteristics as the input for
//  the current pass (which doesn't apply to the exceptions listed above).
//  Similarly, encode_output() enforces a policy based on the LAST_PASS and
//  GAMMA_ENCODE_EVERY_FBO settings.  Together, they result in one of the
//  following two pipelines.
//  Typical pipeline with intermediate sRGB framebuffers:
//      linear_color = pow(pass0_encoded_color, input_gamma);
//      intermediate_output = linear_color;     //  Automatic sRGB encoding
//      linear_color = intermediate_output;     //  Automatic sRGB decoding
//      final_output = pow(intermediate_output, 1.0/output_gamma);
//  Typical pipeline without intermediate sRGB framebuffers:
//      linear_color = pow(pass0_encoded_color, input_gamma);
//      intermediate_output = pow(linear_color, 1.0/intermediate_gamma);
//      linear_color = pow(intermediate_output, intermediate_gamma);
//      final_output = pow(intermediate_output, 1.0/output_gamma);
//  Using GAMMA_ENCODE_EVERY_FBO is much slower, but it's provided as a way to
//  easily get gamma-correctness without banding on devices where sRGB isn't
//  supported.
//
//  Use This Header to Maximize Code Reuse:
//  The purpose of this header is to provide a consistent interface for texture
//  reads and output gamma-encoding that localizes and abstracts away all the
//  annoying details.  This greatly reduces the amount of code in each shader
//  pass that depends on the pass number in the .cgp preset or whether sRGB
//  FBO's are being used: You can trivially change the gamma behavior of your
//  whole pass by commenting or uncommenting 1-3 #defines.  To reuse the same
//  code in your first, Nth, and last passes, you can even put it all in another
//  header file and #include it from skeleton .cg files that #define the
//  appropriate pass-specific settings.
//
//  Rationale for Using Three Macros:
//  This file uses GAMMA_ENCODE_EVERY_FBO instead of an opposite macro like
//  SRGB_PIPELINE to ensure sRGB is assumed by default, which hopefully imposes
//  a lower maintenance burden on each pass.  At first glance it seems we could
//  accomplish everything with two macros: GAMMA_CORRECT_IN / GAMMA_CORRECT_OUT.
//  This works for simple use cases where input_gamma == output_gamma, but it
//  breaks down for more complex scenarios like CRT simulation, where the pass
//  number determines the gamma encoding of the input and output.


///////////////////////////////  BASE CONSTANTS  ///////////////////////////////

//  Set standard gamma constants, but allow users to override them:
#ifndef OVERRIDE_STANDARD_GAMMA
    //  Standard encoding gammas:
    static const float ntsc_gamma = 2.2;    //  Best to use NTSC for PAL too?
    static const float pal_gamma = 2.8;     //  Never actually 2.8 in practice
    //  Typical device decoding gammas (only use for emulating devices):
    //  CRT/LCD reference gammas are higher than NTSC and Rec.709 video standard
    //  gammas: The standards purposely undercorrected for an analog CRT's
    //  assumed 2.5 reference display gamma to maintain contrast in assumed
    //  [dark] viewing conditions: http://www.poynton.com/PDFs/GammaFAQ.pdf
    //  These unstated assumptions about display gamma and perceptual rendering
    //  intent caused a lot of confusion, and more modern CRT's seemed to target
    //  NTSC 2.2 gamma with circuitry.  LCD displays seem to have followed suit
    //  (they struggle near black with 2.5 gamma anyway), especially PC/laptop
    //  displays designed to view sRGB in bright environments.  (Standards are
    //  also in flux again with BT.1886, but it's underspecified for displays.)
    static const float crt_reference_gamma_high = 2.5;  //  In (2.35, 2.55)
    static const float crt_reference_gamma_low = 2.35;  //  In (2.35, 2.55)
    static const float lcd_reference_gamma = 2.5;       //  To match CRT
    static const float crt_office_gamma = 2.2;  //  Circuitry-adjusted for NTSC
    static const float lcd_office_gamma = 2.2;  //  Approximates sRGB
#endif  //  OVERRIDE_STANDARD_GAMMA

//  Assuming alpha == 1.0 might make it easier for users to avoid some bugs,
//  but only if they're aware of it.
#ifndef OVERRIDE_ALPHA_ASSUMPTIONS
    static const bool assume_opaque_alpha = false;
#endif


///////////////////////  DERIVED CONSTANTS AS FUNCTIONS  ///////////////////////

//  gamma-management.h should be compatible with overriding gamma values with
//  runtime user parameters, but we can only define other global constants in
//  terms of static constants, not uniform user parameters.  To get around this
//  limitation, we need to define derived constants using functions.

//  Set device gamma constants, but allow users to override them:
#ifdef OVERRIDE_DEVICE_GAMMA
    //  The user promises to globally define the appropriate constants:
    inline float get_crt_gamma()    {   return crt_gamma;   }
    inline float get_gba_gamma()    {   return gba_gamma;   }
    inline float get_lcd_gamma()    {   return lcd_gamma;   }
#else
    inline float get_crt_gamma()    {   return crt_reference_gamma_high;    }
    inline float get_gba_gamma()    {   return 3.5; }   //  Game Boy Advance; in (3.0, 4.0)
    inline float get_lcd_gamma()    {   return lcd_office_gamma;            }
#endif  //  OVERRIDE_DEVICE_GAMMA

//  Set decoding/encoding gammas for the first/lass passes, but allow overrides:
#ifdef OVERRIDE_FINAL_GAMMA
    //  The user promises to globally define the appropriate constants:
    inline float get_intermediate_gamma()   {   return intermediate_gamma;  }
    inline float get_input_gamma()          {   return input_gamma;         }
    inline float get_output_gamma()         {   return output_gamma;        }
#else
    //  If we gamma-correct every pass, always use ntsc_gamma between passes to
    //  ensure middle passes don't need to care if anything is being simulated:
    inline float get_intermediate_gamma()   {   return ntsc_gamma;          }
    #ifdef SIMULATE_CRT_ON_LCD
        inline float get_input_gamma()      {   return get_crt_gamma();     }
        inline float get_output_gamma()     {   return get_lcd_gamma();     }
    #else
    #ifdef SIMULATE_GBA_ON_LCD
        inline float get_input_gamma()      {   return get_gba_gamma();     }
        inline float get_output_gamma()     {   return get_lcd_gamma();     }
    #else
    #ifdef SIMULATE_LCD_ON_CRT
        inline float get_input_gamma()      {   return get_lcd_gamma();     }
        inline float get_output_gamma()     {   return get_crt_gamma();     }
    #else
    #ifdef SIMULATE_GBA_ON_CRT
        inline float get_input_gamma()      {   return get_gba_gamma();     }
        inline float get_output_gamma()     {   return get_crt_gamma();     }
    #else   //  Don't simulate anything:
        inline float get_input_gamma()      {   return ntsc_gamma;          }
        inline float get_output_gamma()     {   return ntsc_gamma;          }
    #endif  //  SIMULATE_GBA_ON_CRT
    #endif  //  SIMULATE_LCD_ON_CRT
    #endif  //  SIMULATE_GBA_ON_LCD
    #endif  //  SIMULATE_CRT_ON_LCD
#endif  //  OVERRIDE_FINAL_GAMMA

//  Set decoding/encoding gammas for the current pass.  Use static constants for
//  linearize_input and gamma_encode_output, because they aren't derived, and
//  they let the compiler do dead-code elimination.
#ifndef GAMMA_ENCODE_EVERY_FBO
    #ifdef FIRST_PASS
        static const bool linearize_input = true;
        inline float get_pass_input_gamma()     {   return get_input_gamma();   }
    #else
        static const bool linearize_input = false;
        inline float get_pass_input_gamma()     {   return 1.0;                 }
    #endif
    #ifdef LAST_PASS
        static const bool gamma_encode_output = true;
        inline float get_pass_output_gamma()    {   return get_output_gamma();  }
    #else
        static const bool gamma_encode_output = false;
        inline float get_pass_output_gamma()    {   return 1.0;                 }
    #endif
#else
    static const bool linearize_input = true;
    static const bool gamma_encode_output = true;
    #ifdef FIRST_PASS
        inline float get_pass_input_gamma()     {   return get_input_gamma();   }
    #else
        inline float get_pass_input_gamma()     {   return get_intermediate_gamma();    }
    #endif
    #ifdef LAST_PASS
        inline float get_pass_output_gamma()    {   return get_output_gamma();  }
    #else
        inline float get_pass_output_gamma()    {   return get_intermediate_gamma();    }
    #endif
#endif

//  Users might want to know if bilinear filtering will be gamma-correct:
static const bool gamma_aware_bilinear = !linearize_input;


//////////////////////  COLOR ENCODING/DECODING FUNCTIONS  /////////////////////

inline float4 encode_output(const float4 color)
{
    if(gamma_encode_output)
    {
        if(assume_opaque_alpha)
        {
            return float4(pow(color.rgb, float3(1.0/get_pass_output_gamma())), 1.0);
        }
        else
        {
            return float4(pow(color.rgb, float3(1.0/get_pass_output_gamma())), color.a);
        }
    }
    else
    {
        return color;
    }
}

inline float4 decode_input(const float4 color)
{
    if(linearize_input)
    {
        if(assume_opaque_alpha)
        {
            return float4(pow(color.rgb, float3(get_pass_input_gamma())), 1.0);
        }
        else
        {
            return float4(pow(color.rgb, float3(get_pass_input_gamma())), color.a);
        }
    }
    else
    {
        return color;
    }
}

inline float4 decode_gamma_input(const float4 color, const float3 gamma)
{
    if(assume_opaque_alpha)
    {
        return float4(pow(color.rgb, gamma), 1.0);
    }
    else
    {
        return float4(pow(color.rgb, gamma), color.a);
    }
}

//TODO/FIXME: I have no idea why replacing the lookup wrappers with this macro fixes the blurs being offset ¯\_(ツ)_/¯
//#define tex2D_linearize(C, D) decode_input(vec4(texture(C, D)))
// EDIT: it's the 'const' in front of the coords that's doing it

///////////////////////////  TEXTURE LOOKUP WRAPPERS  //////////////////////////

//  "SMART" LINEARIZING TEXTURE LOOKUP FUNCTIONS:
//  Provide a wide array of linearizing texture lookup wrapper functions.  The
//  Cg shader spec Retroarch uses only allows for 2D textures, but 1D and 3D
//  lookups are provided for completeness in case that changes someday.  Nobody
//  is likely to use the *fetch and *proj functions, but they're included just
//  in case.  The only tex*D texture sampling functions omitted are:
//      - tex*Dcmpbias
//      - tex*Dcmplod
//      - tex*DARRAY*
//      - tex*DMS*
//      - Variants returning integers
//  Standard line length restrictions are ignored below for vertical brevity.
/*
//  tex1D:
inline float4 tex1D_linearize(const sampler1D tex, const float tex_coords)
{   return decode_input(tex1D(tex, tex_coords));   }

inline float4 tex1D_linearize(const sampler1D tex, const float2 tex_coords)
{   return decode_input(tex1D(tex, tex_coords));   }

inline float4 tex1D_linearize(const sampler1D tex, const float tex_coords, const int texel_off)
{   return decode_input(tex1D(tex, tex_coords, texel_off));    }

inline float4 tex1D_linearize(const sampler1D tex, const float2 tex_coords, const int texel_off)
{   return decode_input(tex1D(tex, tex_coords, texel_off));    }

inline float4 tex1D_linearize(const sampler1D tex, const float tex_coords, const float dx, const float dy)
{   return decode_input(tex1D(tex, tex_coords, dx, dy));   }

inline float4 tex1D_linearize(const sampler1D tex, const float2 tex_coords, const float dx, const float dy)
{   return decode_input(tex1D(tex, tex_coords, dx, dy));   }

inline float4 tex1D_linearize(const sampler1D tex, const float tex_coords, const float dx, const float dy, const int texel_off)
{   return decode_input(tex1D(tex, tex_coords, dx, dy, texel_off));    }

inline float4 tex1D_linearize(const sampler1D tex, const float2 tex_coords, const float dx, const float dy, const int texel_off)
{   return decode_input(tex1D(tex, tex_coords, dx, dy, texel_off));    }

//  tex1Dbias:
inline float4 tex1Dbias_linearize(const sampler1D tex, const float4 tex_coords)
{   return decode_input(tex1Dbias(tex, tex_coords));   }

inline float4 tex1Dbias_linearize(const sampler1D tex, const float4 tex_coords, const int texel_off)
{   return decode_input(tex1Dbias(tex, tex_coords, texel_off));    }

//  tex1Dfetch:
inline float4 tex1Dfetch_linearize(const sampler1D tex, const int4 tex_coords)
{   return decode_input(tex1Dfetch(tex, tex_coords));  }

inline float4 tex1Dfetch_linearize(const sampler1D tex, const int4 tex_coords, const int texel_off)
{   return decode_input(tex1Dfetch(tex, tex_coords, texel_off));   }

//  tex1Dlod:
inline float4 tex1Dlod_linearize(const sampler1D tex, const float4 tex_coords)
{   return decode_input(tex1Dlod(tex, tex_coords));    }

inline float4 tex1Dlod_linearize(const sampler1D tex, const float4 tex_coords, const int texel_off)
{   return decode_input(tex1Dlod(tex, tex_coords, texel_off));     }

//  tex1Dproj:
inline float4 tex1Dproj_linearize(const sampler1D tex, const float2 tex_coords)
{   return decode_input(tex1Dproj(tex, tex_coords));   }

inline float4 tex1Dproj_linearize(const sampler1D tex, const float3 tex_coords)
{   return decode_input(tex1Dproj(tex, tex_coords));   }

inline float4 tex1Dproj_linearize(const sampler1D tex, const float2 tex_coords, const int texel_off)
{   return decode_input(tex1Dproj(tex, tex_coords, texel_off));    }

inline float4 tex1Dproj_linearize(const sampler1D tex, const float3 tex_coords, const int texel_off)
{   return decode_input(tex1Dproj(tex, tex_coords, texel_off));    }
*/
//  tex2D:
inline float4 tex2D_linearize(const sampler2D tex, float2 tex_coords)
{   return decode_input(texture(tex, tex_coords));   }

inline float4 tex2D_linearize(const sampler2D tex, float3 tex_coords)
{   return decode_input(texture(tex, tex_coords.xy));   }

inline float4 tex2D_linearize(const sampler2D tex, float2 tex_coords, int texel_off)
{   return decode_input(textureLod(tex, tex_coords, texel_off));    }

inline float4 tex2D_linearize(const sampler2D tex, float3 tex_coords, int texel_off)
{   return decode_input(textureLod(tex, tex_coords.xy, texel_off));    }

//inline float4 tex2D_linearize(const sampler2D tex, const float2 tex_coords, const float2 dx, const float2 dy)
//{   return decode_input(texture(tex, tex_coords, dx, dy));   }

//inline float4 tex2D_linearize(const sampler2D tex, const float3 tex_coords, const float2 dx, const float2 dy)
//{   return decode_input(texture(tex, tex_coords, dx, dy));   }

//inline float4 tex2D_linearize(const sampler2D tex, const float2 tex_coords, const float2 dx, const float2 dy, const int texel_off)
//{   return decode_input(texture(tex, tex_coords, dx, dy, texel_off));    }

//inline float4 tex2D_linearize(const sampler2D tex, const float3 tex_coords, const float2 dx, const float2 dy, const int texel_off)
//{   return decode_input(texture(tex, tex_coords, dx, dy, texel_off));    }

//  tex2Dbias:
//inline float4 tex2Dbias_linearize(const sampler2D tex, const float4 tex_coords)
//{   return decode_input(tex2Dbias(tex, tex_coords));   }

//inline float4 tex2Dbias_linearize(const sampler2D tex, const float4 tex_coords, const int texel_off)
//{   return decode_input(tex2Dbias(tex, tex_coords, texel_off));    }

//  tex2Dfetch:
//inline float4 tex2Dfetch_linearize(const sampler2D tex, const int4 tex_coords)
//{   return decode_input(tex2Dfetch(tex, tex_coords));  }

//inline float4 tex2Dfetch_linearize(const sampler2D tex, const int4 tex_coords, const int texel_off)
//{   return decode_input(tex2Dfetch(tex, tex_coords, texel_off));   }

//  tex2Dlod:
inline float4 tex2Dlod_linearize(const sampler2D tex, float4 tex_coords)
{   return decode_input(textureLod(tex, tex_coords.xy, 0.0));    }

inline float4 tex2Dlod_linearize(const sampler2D tex, float4 tex_coords, int texel_off)
{   return decode_input(textureLod(tex, tex_coords.xy, texel_off));     }
/*
//  tex2Dproj:
inline float4 tex2Dproj_linearize(const sampler2D tex, const float3 tex_coords)
{   return decode_input(tex2Dproj(tex, tex_coords));   }

inline float4 tex2Dproj_linearize(const sampler2D tex, const float4 tex_coords)
{   return decode_input(tex2Dproj(tex, tex_coords));   }

inline float4 tex2Dproj_linearize(const sampler2D tex, const float3 tex_coords, const int texel_off)
{   return decode_input(tex2Dproj(tex, tex_coords, texel_off));    }

inline float4 tex2Dproj_linearize(const sampler2D tex, const float4 tex_coords, const int texel_off)
{   return decode_input(tex2Dproj(tex, tex_coords, texel_off));    }
*/
/*
//  tex3D:
inline float4 tex3D_linearize(const sampler3D tex, const float3 tex_coords)
{   return decode_input(tex3D(tex, tex_coords));   }

inline float4 tex3D_linearize(const sampler3D tex, const float3 tex_coords, const int texel_off)
{   return decode_input(tex3D(tex, tex_coords, texel_off));    }

inline float4 tex3D_linearize(const sampler3D tex, const float3 tex_coords, const float3 dx, const float3 dy)
{   return decode_input(tex3D(tex, tex_coords, dx, dy));   }

inline float4 tex3D_linearize(const sampler3D tex, const float3 tex_coords, const float3 dx, const float3 dy, const int texel_off)
{   return decode_input(tex3D(tex, tex_coords, dx, dy, texel_off));    }

//  tex3Dbias:
inline float4 tex3Dbias_linearize(const sampler3D tex, const float4 tex_coords)
{   return decode_input(tex3Dbias(tex, tex_coords));   }

inline float4 tex3Dbias_linearize(const sampler3D tex, const float4 tex_coords, const int texel_off)
{   return decode_input(tex3Dbias(tex, tex_coords, texel_off));    }

//  tex3Dfetch:
inline float4 tex3Dfetch_linearize(const sampler3D tex, const int4 tex_coords)
{   return decode_input(tex3Dfetch(tex, tex_coords));  }

inline float4 tex3Dfetch_linearize(const sampler3D tex, const int4 tex_coords, const int texel_off)
{   return decode_input(tex3Dfetch(tex, tex_coords, texel_off));   }

//  tex3Dlod:
inline float4 tex3Dlod_linearize(const sampler3D tex, const float4 tex_coords)
{   return decode_input(tex3Dlod(tex, tex_coords));    }

inline float4 tex3Dlod_linearize(const sampler3D tex, const float4 tex_coords, const int texel_off)
{   return decode_input(tex3Dlod(tex, tex_coords, texel_off));     }

//  tex3Dproj:
inline float4 tex3Dproj_linearize(const sampler3D tex, const float4 tex_coords)
{   return decode_input(tex3Dproj(tex, tex_coords));   }

inline float4 tex3Dproj_linearize(const sampler3D tex, const float4 tex_coords, const int texel_off)
{   return decode_input(tex3Dproj(tex, tex_coords, texel_off));    }
/////////*

//  NONSTANDARD "SMART" LINEARIZING TEXTURE LOOKUP FUNCTIONS:
//  This narrow selection of nonstandard tex2D* functions can be useful:

//  tex2Dlod0: Automatically fill in the tex2D LOD parameter for mip level 0.
//inline float4 tex2Dlod0_linearize(const sampler2D tex, const float2 tex_coords)
//{   return decode_input(tex2Dlod(tex, float4(tex_coords, 0.0, 0.0)));   }

//inline float4 tex2Dlod0_linearize(const sampler2D tex, const float2 tex_coords, const int texel_off)
//{   return decode_input(tex2Dlod(tex, float4(tex_coords, 0.0, 0.0), texel_off));    }


//  MANUALLY LINEARIZING TEXTURE LOOKUP FUNCTIONS:
//  Provide a narrower selection of tex2D* wrapper functions that decode an
//  input sample with a specified gamma value.  These are useful for reading
//  LUT's and for reading the input of pass0 in a later pass.

//  tex2D:
inline float4 tex2D_linearize_gamma(const sampler2D tex, const float2 tex_coords, const float3 gamma)
{   return decode_gamma_input(texture(tex, tex_coords), gamma);   }

inline float4 tex2D_linearize_gamma(const sampler2D tex, const float3 tex_coords, const float3 gamma)
{   return decode_gamma_input(texture(tex, tex_coords.xy), gamma);   }

//inline float4 tex2D_linearize_gamma(const sampler2D tex, const float2 tex_coords, const int texel_off, const float3 gamma)
//{   return decode_gamma_input(texture(tex, tex_coords, texel_off), gamma);    }

//inline float4 tex2D_linearize_gamma(const sampler2D tex, const float3 tex_coords, const int texel_off, const float3 gamma)
//{   return decode_gamma_input(texture(tex, tex_coords, texel_off), gamma);    }

//inline float4 tex2D_linearize_gamma(const sampler2D tex, const float2 tex_coords, const float2 dx, const float2 dy, const float3 gamma)
//{   return decode_gamma_input(texture(tex, tex_coords, dx, dy), gamma);   }

//inline float4 tex2D_linearize_gamma(const sampler2D tex, const float3 tex_coords, const float2 dx, const float2 dy, const float3 gamma)
//{   return decode_gamma_input(texture(tex, tex_coords, dx, dy), gamma);   }

//inline float4 tex2D_linearize_gamma(const sampler2D tex, const float2 tex_coords, const float2 dx, const float2 dy, const int texel_off, const float3 gamma)
//{   return decode_gamma_input(texture(tex, tex_coords, dx, dy, texel_off), gamma);    }

//inline float4 tex2D_linearize_gamma(const sampler2D tex, const float3 tex_coords, const float2 dx, const float2 dy, const int texel_off, const float3 gamma)
//{   return decode_gamma_input(texture(tex, tex_coords, dx, dy, texel_off), gamma);    }
/*
//  tex2Dbias:
inline float4 tex2Dbias_linearize_gamma(const sampler2D tex, const float4 tex_coords, const float3 gamma)
{   return decode_gamma_input(tex2Dbias(tex, tex_coords), gamma);   }

inline float4 tex2Dbias_linearize_gamma(const sampler2D tex, const float4 tex_coords, const int texel_off, const float3 gamma)
{   return decode_gamma_input(tex2Dbias(tex, tex_coords, texel_off), gamma);    }

//  tex2Dfetch:
inline float4 tex2Dfetch_linearize_gamma(const sampler2D tex, const int4 tex_coords, const float3 gamma)
{   return decode_gamma_input(tex2Dfetch(tex, tex_coords), gamma);  }

inline float4 tex2Dfetch_linearize_gamma(const sampler2D tex, const int4 tex_coords, const int texel_off, const float3 gamma)
{   return decode_gamma_input(tex2Dfetch(tex, tex_coords, texel_off), gamma);   }
*/
//  tex2Dlod:
inline float4 tex2Dlod_linearize_gamma(const sampler2D tex, float4 tex_coords, float3 gamma)
{   return decode_gamma_input(textureLod(tex, tex_coords.xy, 0.0), gamma);    }

inline float4 tex2Dlod_linearize_gamma(const sampler2D tex, float4 tex_coords, int texel_off, float3 gamma)
{   return decode_gamma_input(textureLod(tex, tex_coords.xy, texel_off), gamma);     }


#endif  //  GAMMA_MANAGEMENT_H