// 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 pyramid [Noise] [Seed]
//
// xs_begin
// author : '@lmcdx.bsky.social'
// 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 noise = m_noise / 100.0;

bool no_axis_mode = all(equal(ivec3(i_axis), ivec3(0)));
bvec3 axis_mode = no_axis_mode ? bvec3(true) : equal(ivec3(i_axis), ivec3(1));

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);
}

bool isSelectedPal(float p) {
	for (int i = 0; i < i_num_color_sels; i += 1) {
		if (p == color_sel(float(i))) {
			return true;
		}
	}
	return false;
}

bool isSelectedPal(vec3 v) {
	return isSelectedPal(voxel(v));
}

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 (index == 0.0) {
		float index_beneath = voxel(v - vec3(0.0, 0.0, 1.0));

		if (isSelectedPal(index_beneath)) {
			float t = 0.0;
			float a = 0.0;

			if (axis_mode.x) {
				t += 2.0;
				a += (isSelectedPal(vec3(v.x - 1.0, v.y, v.z - 1.0)) ? 1.0 : 0.0) +
					 (isSelectedPal(vec3(v.x + 1.0, v.y, v.z - 1.0)) ? 1.0 : 0.0);
			}
			if (axis_mode.y) {
				t += 2.0;
				a += (isSelectedPal(vec3(v.x, v.y - 1.0, v.z - 1.0)) ? 1.0 : 0.0) +
					 (isSelectedPal(vec3(v.x, v.y + 1.0, v.z - 1.0)) ? 1.0 : 0.0);
			}

			if (a == t) {
				float z = hash(v, a);

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

	return index;
}