// Copyright (c) 2023 Lachlan McDonald
// This work is licensed under the MIT License (MIT)
// https://github.com/lachlanmcdonald/magicavoxel-shaders
//
// This script utilises or modifies code from other projects or publications.
// Please see the attributions below for more information:
//
// 1. Copyright (c) 2020 ValgoBoi <https://github.com/ValgoBoi/clover-noise>
//    MIT License (MIT)
//    https://github.com/ValgoBoi/clover-noise/blob/master/LICENSE
//
// xs cover [Headroom] [Noise] [Seed]
//
// xs_begin
// author : '@lmcdx.bsky.social'
// arg : { name = 'Headroom'  var = 'm_headroom'  range = '1 256'  value = '1'  step = '1'  precision = '0' }
// arg : { name = 'Noise'  var = 'm_noise'  range = '0 100'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Seed'  var = 'global_seed'  range = '1 100'  value = '1'  step = '1'  precision = '0' }
// xs_end

float headroom = m_headroom;
float noise = m_noise / 100.0;

float hash(vec2 p, float seed) {
	p += seed + global_seed;
	return fract(1e4 * sin(17.0 * p.x + p.y * 0.1) * (0.1 + abs(sin(p.y * 13.0 + p.x))));
}

float hash(vec3 co, float seed) {
	return hash(vec2(hash(co.xy, seed), co.z), seed);
}

float pal(float p) {
	float f = floor(mix(0.0, float(i_num_color_sels), p));
	return color_sel(f);
}

float map(vec3 v) {
	float index = voxel(v);

	if (voxel(vec3(v.x, v.y, v.z - 1.0)) > 0.0) {
		for (float z = 0.0; z < headroom; z += 1.0) {
			if (voxel(vec3(v.x, v.y, v.z + z)) > 0.0) {
				return index;
			}
		}

		float d = hash(v, 0.0);
		float z = hash(v, 128.0);

		if (noise == 0.0 || z > noise) {
			return pal(d);
		} else {
			return 0.0;
		}
	}

	return index;
}