This pack includes a selective (per-hue) color grading feature and a vignette
post-processing effect ported and adapted from Photon Shaders
(https://www.complementary.dev / https://github.com/sixthsurge/Photon),
Copyright (C) 2021-2025 Benjamin Stott ("SixthSurge"). See PHOTON_LICENSE.txt
for the full license text, which must be included in redistributions of this
pack per Photon's terms.

Files affected:
  - shaders/lib/colors/selectiveColorGrade.glsl (new file, adapted from
    Photon's shaders/program/c14_color_grading.fsh - the grade_output() and
    vignette() functions - and shaders/include/utility/color.glsl /
    shaders/include/global.glsl, which supplied rgb_to_hsl(), hsl_to_rgb(),
    isolate_hue(), pulse(), cubic_smooth() and the gain() curve. Renamed
    with an "SCG_" prefix here to avoid clashing with this pack's own
    naming, and adapted from Photon's ACEScg/rec.2020 working space to
    this pack's existing display-referred color pipeline.)
  - shaders/lib/common.glsl        (added the SELECTIVE_COLOR_GRADE,
    SELECTIVE_GRADE_ORANGE/TEAL/GREEN_SAT/GREEN_HUE_SHIFT/GAIN, VIGNETTE and
    VIGNETTE_INTENSITY #define options - same names/defaults Photon uses for
    its GRADE_* and VIGNETTE_INTENSITY sliders, so the settings will feel
    familiar to anyone who has used Photon)
  - shaders/program/composite5.glsl (added the #include, the vignette call
    before tonemapping, and the DoSelectiveColorGrade() call after this
    pack's existing tonemap + saturation/warm-grade passes)
  - shaders/shaders.properties      (added the GUI entries for the above)

Per Photon's license: you may use, modify (for personal use), and
redistribute modified or unmodified portions of Photon, EXCEPT you may not
redistribute Photon or a derivative work (this pack, once it includes this
ported code) on platforms that pay creators (e.g. Modrinth, CurseForge)
without SixthSurge's explicit written permission, and you may not charge
money for it without that permission. Redistributing as part of a
(commercial) modpack is explicitly allowed. If you strip this feature back
out of the pack, you can also remove this notice and PHOTON_LICENSE.txt.

Note: Photon does not have an image/texture-based 3D LUT system (its "LUT"
occurrences in source are unrelated sky-scattering lookup tables, not color
grading) - what was actually ported here is Photon's procedural selective
HSL color grading and vignette, which is a different technique from this
pack's existing image-based LUT feature (see NOTICE_LUT_PORT.txt), not a
replacement for it. Both now coexist in the pipeline.
