Color - Threshold.osl

// ColorThreshold Shader
// ColorThreshold by Philippe Groarke
// Copyright 2022 Philippe Groarke, All rights reserved. This file is licensed under Apache 2.0 license
// https://github.com/ADN-DevTech/3dsMax-OSL-Shaders/blob/master/LICENSE.txt

#include "C:\Users\groarkp\code\3dsmax-plugins\OSL\FeaOSL\include\fea_interpolate.osl"

#define color_passthrough_opts \
		"None:0" \
		"|Above Intensity:1" \
		"|Below Intensity:2" \
		"|Pick Intensity:3" \
		"|Pick Color:4"

color color_passthrough(int mode, color source, color threshold, float pick_range, color mask) {
	color ret = source;
	if (mode == 0) {
		return ret;
	}

	float avg_source = fea_average(source);
	float avg_thresh = fea_average(threshold);

	if (mode == 1) {
		ret = avg_source >= avg_thresh ? source : mask;
	} else if (mode == 2) {
		ret = avg_source <= avg_thresh ? source : mask;
	} else if (mode == 3) {
		ret = abs(avg_source - avg_thresh) < pick_range ? source : mask;
	} else if (mode == 4) {
		color diff = abs(source - threshold);
		ret = diff[0] < pick_range && diff[1] < pick_range && diff[2] < pick_range ? source : mask;
	}

	return ret;
}

shader ColorThreshold
[[
	string help  =
		"<h3>Color Threshold</h3>"
		"Filter or pick colors from input. Mask the rest."
		,
	string label = "Color - Threshold"
]]
(
	int in_mode = 0
	[[
		string widget = "mapper",
		string label = "Mode",
		string options =
			color_passthrough_opts
			,
		string help = "Filter mode.",
		int connectable = 0,
	]],

	float in_pick_range = 0.02
	[[
		string label = "Pick Range",
		string help = "The +/- range with which to pick intensities or colors. The higher the value, the wider the range picked.",
		float min = 0.0,
		float max = 0.5,
		int connectable = 0,
	]],

	color in_source = 1.0
	[[
		string label = "Source",
		string help = "The input color to filter.",
	]],

	color in_threshold = 0.0
	[[
		string label = "Target",
		string help = "Either the threshold value or the target intensity/color for pick mode.\nWarning : When using the color picker in the viewport, the actual result will be shaded and usually incorrect. You can use the color picker on a material's preview in the SME graph to get a non-shaded source color.",
	]],

	color in_mask = 1.0
	[[
		string label = "Mask",
		string help = "When the condition is true, the replacement color.",
	]],

	output color Out = 0
)
{
	Out = color_passthrough(in_mode, in_source, in_threshold, in_pick_range, in_mask);
}