UberColorCorrect

// Color Correction
// ColorCorrect.osl, by Zap Andersson
// Modified: 2021-12-20 by Saul Espinosa for Redshift 3D
// Removed Max UI specific options and added Page grouping Metadata
// Copyright 2020 Autodesk Inc, All rights reserved. This file is licensed under Apache 2.0 license
//    https://github.com/ADN-DevTech/3dsMax-OSL-Shaders/blob/master/LICENSE.txt
float remap(color In, int mapping)
{
    if (mapping < 3)
        return In[mapping];
    if (mapping < 6)
        return 1.0 - In[mapping-3];
    if (mapping == 6) return luminance(In);
    if (mapping == 7) return 1.0 - luminance(In);
    if (mapping == 8) return 0.0;
    return 1.0;
}
shader UberColorCorrect
[[ string label   = "Color Correction",
   // string category = "Color Correction",
   string version = "1.5" ]]
(
    color Input = 0.18 [[string page = "Input"]],
    int   Bypass = 0          [[ string widget = "checkBox", string page = "Input" ]],
    float Overall = 1.0       [[ float min = 0.0, float max = 1.0, string page = "Input" ]],
    int   HueRange = 0        [[ string widget = "checkBox", string page = "Hue Ranges" ]],
    color AffectHue = color(1.0, 0.4, 0.3) [[string page = "Hue Ranges"]],
    float HueRangeWidth    = 10  [[ float min = 0.0, float max = 360, float step = 1.0, string page = "Hue Ranges" ]],
    float HueRangeSoftness = 10  [[ float min = 0.0, float max = 360, float step = 1.0, string page = "Hue Ranges" ]],
    int   ChannelMapping = 0  [[ string widget = "checkBox", string page = "Channels" ]],    
    int   RedMapping   = 0 
        [[ 
        int connectable = 0, 
        string page = "Channels",
        string widget = "mapper",
        string options = 
              "Red:0|Green:1|Blue:2|"
              "Red (Inverse):3|Green (Inverse):4|Blue (Inverse):5|"
              "Luminance:6|Luminance (Inverse):7|Zero:8|One:9" ]],    
    int   GreenMapping = 1
        [[ int connectable = 0, 
        string page = "Channels",
        string widget = "mapper",
        string options = 
              "Red:0|Green:1|Blue:2|"
              "Red (Inverse):3|Green (Inverse):4|Blue (Inverse):5|"
              "Luminance:6|Luminance (Inverse):7|Zero:8|One:9" ]],        
    int   BlueMapping  = 2    
        [[ int connectable = 0, 
        string page = "Channels",
        string widget = "mapper",
        string options = 
              "Red:0|Green:1|Blue:2|"
              "Red (Inverse):3|Green (Inverse):4|Blue (Inverse):5|"
              "Luminance:6|Luminance (Inverse):7|Zero:8|One:9" ]],    
    int   BrightnessAdjustment = 1 [[ string widget = "checkBox", string page = "Value Adjustments" ]],    
    int   Invert          = 0 [[ string widget = "checkBox", int connectable=0, string page = "Value Adjustments" ]],
    float Brightness      = 1.0 [[string page = "Value Adjustments"]],
    float Contrast        = 1.0 [[string page = "Value Adjustments"]],
    float Lift            = 0.0 [[string page = "Value Adjustments"]],
    float Pivot           = 0.5 [[string page = "Value Adjustments"]],
    int   InverseGamma    = 0 [[ string widget = "checkBox", int connectable=0, string page = "Value Adjustments" ]],    
    float Gamma           = 1.0 [[string page = "Value Adjustments"]],
    int   ColorAdjustment = 0 [[ string widget = "checkBox", int connectable=0, string page = "Color Adjustments" ]],    
    float HueShift        = 0.0 [[ float min = -1.0, float max = 1.0, string page = "Color Adjustments" ]],
    float Saturation      = 1.0 [[ float min = 0.0, float max = 10.0, string page = "Color Adjustments" ]],
    color TintColor       = 1.0 [[ string page = "Color Adjustments"]],
    float TintStrength    = 0.0 [[ float min = 0.0, float max = 1.0, string page = "Color Adjustments" ]],
    int   OutputTint = 0      [[ string widget = "checkBox", int connectable=0, string page = "Output Adjustments" ]],    
    color Shadows    = 0.0 [[ string page = "Output Adjustments"]],
    color Midtones   = 0.2 [[ string page = "Output Adjustments"]],
    color Highlights = 1.0 [[ string page = "Output Adjustments"]],
    float MidtoneLum = 0.2 [[ float min = 0.0, float max = 1.0, string page = "Output Adjustments" ]],
    int   Clamp      = 1      [[ string widget = "checkBox", int connectable=0, string page = "Output Clamp" ]],    
    float ClampLow   = 0.0 [[string page = "Output Clamp"]],
    float ClampHi    = 1.0 [[string page = "Output Clamp"]],
    // Outputs
    output color Out = 0.0,
    output float R = 0.0,
    output float G = 0.0,
    output float B = 0.0
)
{
    float effect = Overall;
    Out = Input;        
    if (!Bypass)
    {
        // Apply only to hue range
        if (HueRange)
        {
            // Tramsform to HSV space    
            color hsv  = transformc("rgb", "hsv", Input);
            // Tramsform to HSV space    
            color hsv2 = transformc("rgb", "hsv", AffectHue);
            float huedifference = fabs(hsv[0] - hsv2[0]);
            // If distance in hue is larger than half
            // the color wheel, measure the other way around
            if (huedifference > 0.5)
                huedifference = 1.0 - huedifference;
            float HRW = HueRangeWidth / 360.0 / 2.0;
            float HRS = HueRangeSoftness / 360.0;
            // Are we outside the hue range? Then we need to modulate
            // the effect value to apply the effect less (or not at all)
            if (huedifference > HRW)
            {
                // Outside range - apply softness (if any)
                if (HRS > 0.0)
                    effect *= smoothstep(0.0, 1.0, 1.0 - (huedifference - HRW) / HRS);
                else
                    effect = 0.0; // No softness - just hard cut effect to zero
            }
        }
        // Apply the channel mapping
        if (ChannelMapping)
        {
            Out[0] = remap(Input, RedMapping);
            Out[1] = remap(Input, GreenMapping);
            Out[2] = remap(Input, BlueMapping);
        }
        // Brightness adjustment section
        if (BrightnessAdjustment)
        {
            // Invert, if requested
            if (Invert) Out = 1.0 - Out;
            // Multiply by Brightness
            Out = Out * Brightness;
            // Scale around Pivot by Contrast
            Out = ((Out - Pivot) * Contrast) + Pivot;
            // Add Lift
            Out = Out + Lift;
            // Apply Gamma
            if (Gamma != 1.0)
                Out = pow(max(0.0, Out), InverseGamma?1.0/Gamma:Gamma);
        }        
        // Color adjustment section
        if (ColorAdjustment)
        {
            // Tramsform to HSV space    
            color hsv = transformc("rgb", "hsv", Out);
            hsv[0] += HueShift;
            hsv[1] *= Saturation;
            // Convert back to RGB
            Out = transformc("hsv", "rgb", hsv);            
            // Mix with tint color scaled by value            
            Out = mix(Out, TintColor * hsv[2], TintStrength);
        }
        // Output Tint Section
        if (OutputTint)
        {
            color below = clamp((Out / MidtoneLum), 0.0, 1.0);
            color above = clamp((Out - MidtoneLum) / (1.0 - MidtoneLum), 0.0, 1.0);
            Out = mix(Shadows, mix(Midtones, Highlights, above), below);            
        }                                        
        if (Clamp)        
            Out = clamp(Out, ClampLow, ClampHi);
        // Do the overall mix in of the effect    
        Out = mix(Input, Out, effect);            
    }
    // Output individual channels for convenience    
    R = Out[0];
    G = Out[1];
    B = Out[2];
}