// Copyright (c) 2023 Lachlan McDonald
// This work is licensed under the MIT License (MIT)
// https://github.com/lachlanmcdonald/magicavoxel-shaders
//
// xs brush/zigzag_range [Direction] [Width]
//
// xs_begin
// author : '@lmcdx.bsky.social'
// arg : { name = 'Direction'  var = 'm_direction'  range = '0 3'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Width'  var = 'm_width'  range = '1 256'  value = '2'  step = '1'  precision = '0' }
// xs_end

int direction = int(m_direction);
float width = m_width;

float roundf(float f) {
	return f >= 0.5 ? ceil(f) : floor(f);
}

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

float map(vec3 v) {
	v = floor(v);

	if (direction == 1) {
		v.y = -v.y;
	} else if (direction == 2) {
		v.x = -v.x;
		v.y = -v.y;
	} else if (direction == 3) {
		v.x = -v.x;
	}

	float size = floor(float(i_num_color_sels) * width);
	float row = floor(v.y / size);
	float col = floor(v.x / size);
	vec2 k = v.xy - vec2(col, row) * size;

	float p = mod(row + col, 2.0) == 0.0 ? min(k.x, k.y) : max(k.x, k.y);
	return color_sel(floor(p / width));
}