// Copyright (c) 2023 Lachlan McDonald
// This work is licensed under the MIT License (MIT)
// https://github.com/lachlanmcdonald/magicavoxel-shaders
//
// xs brush/diagonal [Direction] [Width A] [Width B] [Width C] [Width D] [Offset] [Shuffle]
//
// xs_begin
// author : '@lmcdx.bsky.social'
// arg : { name = 'Direction'  var = 'm_direction'  range = '0 5'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Width A'  var = 'm_width_a'  range = '0 32'  value = '2'  step = '1'  precision = '0' }
// arg : { name = 'Width B'  var = 'm_width_b'  range = '0 32'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Width C'  var = 'm_width_c'  range = '0 32'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Width D'  var = 'm_width_d'  range = '0 32'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Offset'  var = 'm_offset'  range = '0 256'  value = '0'  step = '1'  precision = '0' }
// arg : { name = 'Shuffle'  var = 'm_shuffle'  range = '0 256'  value = '0'  step = '1'  precision = '0' }
// xs_end

int direction = int(m_direction);
float width_1 = m_width_a;
float width_2 = m_width_b;
float width_3 = m_width_c;
float width_4 = m_width_d;
float offset = m_offset;
float shuffle = m_shuffle;

int imod(int a, int b) {
	return int(mod(float(a), float(b)));
}

float map(vec3 v) {
	// Line widths
	int width_count = 0;
	float widths[4];

	if (width_1 >= 1.0) {
		widths[width_count] = width_1;
		width_count += 1;
	}
	if (width_2 >= 1.0) {
		widths[width_count] = width_2;
		width_count += 1;
	}
	if (width_3 >= 1.0) {
		widths[width_count] = width_3;
		width_count += 1;
	}
	if (width_4 >= 1.0) {
		widths[width_count] = width_4;
		width_count += 1;
	}

	// Adjustments for direction
	float x;
	float z;

	if (direction == 0) {
		v.z = 0.0;
	} else if (direction == 2) {
		v.z = -v.z;
	} else if (direction == 3) {
		v.x = -v.x;
		v.z = 0.0;
	} else if (direction == 4) {
		v.x = -v.x;
	} else if (direction == 5) {
		v.x = -v.x;
		v.z = -v.z;
	}

	int iter = 0;
	float p = abs(v.x + v.y + v.z + offset);
	float f = 0.0;

	while (f < p) {
		int idx = imod(iter, width_count);
		float w = widths[idx];
		iter += 1;
		f += w;
	}

	if (i_num_color_sels == 1) {
		float i = mod(float(iter), 2.0);
		return i == 0.0 ? color_sel(i) : 0.0;
	} else {
		float i = mod(float(iter) + shuffle, float(i_num_color_sels));
		return color_sel(i);
	}
}