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use std::f32::consts::PI;
use cgmath::Vector3;
use cgmath::prelude::*;
type Vector = Vector3<f32>;
pub fn sd_sphere(point: Vector, center: Vector, radius: f32) -> f32 {
(point - center).magnitude() - radius
}
pub fn sd_box(point: Vector, center: Vector, size: Vector) -> f32 {
let diff = center - point;
let q = diff.map(|n| n.abs()) - size / 2.0;
return q.map(|n| n.max(0.0)).magnitude() + (q.y.max(q.z).max(q.x)).min(0.0)
}
pub fn sd_gear(point: Vector, time: f32, center: Vector, radius: f32, thickness: f32, turn_rate: f32) -> f32 {
let mut dist: f32;
let thickness_over_2 = thickness / 2.0;
let thickness_over_4 = thickness / 4.0;
// Ring
{
let cylinder_dist = (Vector::new(0.0, point.y, point.z) - center).magnitude() - (radius - thickness_over_4);
dist = cylinder_dist.abs() - thickness_over_2; // Make cylinder hollow
}
// Teeth
{
let sector_angle: f32 = 2.0 * PI / 12.0;
// Account for rotation with time
let angle = sector_angle * time / turn_rate;
let rotated_point = Vector::new(
point.x,
point.y * angle.cos() - point.z * angle.sin(),
point.y * angle.sin() + point.z * angle.cos()
);
// Map all space to the first sector
let point_angle = (rotated_point.z / rotated_point.y).atan();
let angle2 = -sector_angle * (point_angle / sector_angle).round();
let mapped_point = Vector::new(
rotated_point.x,
(rotated_point.y * angle2.cos() - rotated_point.z * angle2.sin()).abs(),
rotated_point.y * angle2.sin() + rotated_point.z * angle2.cos()
);
let center = Vector { x: 0.0, y: radius + thickness_over_2, z: 0.0 };
let size = Vector::new(thickness, thickness * 2.0, thickness);
// Make teeth smooth by subtracting some amount
dist = dist.min(sd_box(mapped_point, center, size) - thickness_over_4);
}
// Take a slice
dist = dist.max(point.x.abs() - thickness_over_2);
return dist;
}
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