Lucrecious

shader_type canvas_item;

const vec4 background = vec4(1., 1., 1., 0.);

float dist(vec4 c1, vec4 c2) {
	return (c1 == c2) ? 0.0 : abs(c1.r - c2.r) + abs(c1.g - c2.g) + abs(c1.b - c2.b);
}

bool similar(vec4 c1, vec4 c2, vec4 input) {
	return (c1 == c2 || (dist(c1, c2) <= dist(input, c2) && dist(c1, c2) <= dist(input, c1)));

Lucrecious

shader_type canvas_item;

const vec4 background = vec4(1., 1., 1., 0.);

uniform float pixel_scale: hint_range(0.0, 1.0) = 1.0;

float dist(vec4 c1, vec4 c2) {
	return (c1 == c2) ? 0.0 : abs(c1.r - c2.r) + abs(c1.g - c2.g) + abs(c1.b - c2.b);
}