VESPERA SHADERS  --  CREDITS


AUTHORSHIP
----------
Vespera Shaders was designed and written from scratch for this project with
the assistance of an AI model (Anthropic's Claude). No source code,
configuration or asset was taken from any existing shader pack.

The pack was verified by compiling and linking all 29 program pairs against a
real OpenGL 4.6 compatibility driver across 45 different option
configurations (1305 successful compiles) before release.


TECHNIQUES USED
---------------
The pack implements a number of published, freely documented rendering
techniques. They were implemented from the public description of each
algorithm, not from anyone's source code. Credit where it is due:

  Cook-Torrance microfacet BRDF
      R. Cook and K. Torrance, 1982.

  GGX / Trowbridge-Reitz normal distribution and the height correlated
  Smith visibility term
      B. Walter et al., 2007; E. Heitz, 2014.

  Split sum environment BRDF approximation
      B. Karis, Epic Games, 2013.

  Hammon diffuse approximation
      E. Hammon Jr., GDC 2017.

  Henyey-Greenstein phase function
      L. Henyey and J. Greenstein, 1941.

  Beer-Powder cloud extinction and the two lobe cloud phase
      A. Schneider and N. Vos, "The Real-Time Volumetric Cloudscapes of
      Horizon Zero Dawn", SIGGRAPH 2015.

  Filmic tone mapping curve
      T. Lottes, AMD, 2016 (parametric curve, retuned for this pack).

  ACES filmic approximation
      K. Narkowicz, 2015.

  Uncharted 2 tone mapping curve
      J. Hable, 2010.

  Octahedral normal encoding
      Q. Meyer et al., 2010; C. Cigolle et al., JCGT 2014.

  Temporal anti aliasing with neighbourhood clamping in YCoCg
      B. Karis, "High Quality Temporal Supersampling", SIGGRAPH 2014.

  Catmull-Rom history resampling
      Standard bicubic filtering, five tap optimisation widely published.

  Vogel disc sampling
      H. Vogel, 1979; applied to shadow filtering as described by
      A. Pettineo.

  Interleaved gradient noise
      J. Jimenez, "Next Generation Post Processing in Call of Duty:
      Advanced Warfare", SIGGRAPH 2014.

  Branchless orthonormal basis construction
      T. Duff et al., JCGT 2017.

  Parallax occlusion mapping
      T. Tatarchuk, 2006.

  Colour temperature to RGB approximation
      T. Helland, 2012, after the Planckian locus.

  LabPBR 1.3 material format
      The LabPBR community specification. Vespera reads the format; the
      specification itself belongs to its authors.


PLATFORM
--------
  Iris Shaders   --  the shader loader this pack targets.
  Sodium         --  the renderer Iris builds on.
  Minecraft      --  a trademark of Mojang Studios. This project is not
                     affiliated with, endorsed by, or sponsored by Mojang
                     Studios or Microsoft.


THANK YOU
---------
To everyone who has ever published a breakdown of how their renderer works
instead of keeping it to themselves. This pack exists because that culture
exists.
