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use cgmath::Matrix3;
use cgmath::Vector3;
use cgmath::prelude::*;
use ncurses::addch;
use ncurses::addstr;
use std::f32;
use std::f32::consts::PI;
use std::time::Instant;
type Vector = Vector3<f32>;
pub const HEIGHT: i32 = 60;
pub const WIDTH: i32 = HEIGHT * 3;
#[derive(Debug)]
pub struct Camera {
pub time: f32,
pub position: Vector,
pub direction: Vector,
pub up: Vector,
pub light: Vector,
pub angle: f32,
pub distance: f32,
pub brightness: f32,
pub aspect_ratio: f32,
pub speed: f32,
pub turn_rate: f32,
pub width: f32,
pub height: f32,
pub palette: Vec<char>,
}
fn softmin(left: f32, right: f32, k: f32) -> f32 {
// return left.min(right);
let h = (k-(left-right).abs()).max(0.0) / k;
return left.min(right) - h*h*k*(1.0/4.0);
}
fn sd_sphere(point: Vector, center: Vector, radius: f32) -> f32 {
(point - center).magnitude() - radius
}
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)
}
impl Camera {
pub fn sd_gear(&self, point: Vector, 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 * self.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;
}
pub fn sdf(&self, point: Vector) -> f32 {
self.sd_gear(point, Vector::zero(), 3.0, 0.6, 10.0)
}
pub fn render(& mut self) {
// Linear transormation operator for calculating screen position
// Assumes "initial" screen is perpendicular to OX
// and it's bottom edge is parallel to OY
let operator = Matrix3::from_cols(
self.direction * self.distance,
self.direction.cross(self.up) * self.width,
-self.up * self.height,
);
let mut ray_dir = operator * Vector::new(1.0, -0.5, -0.5); // Corner
let step_v = operator * Vector3::unit_z() / HEIGHT as f32;
let step_h = operator * Vector3::unit_y() / WIDTH as f32;
for _i in 0..HEIGHT as usize {
ray_dir += step_v;
let mut row = "\n".to_string();
for _j in 0..WIDTH as usize {
ray_dir += step_h;
let collision = self.ray_marching(self.position, ray_dir);
let brightness = match collision {
Some(point) => self.light_point(point),
None => 0.0
};
row.push(self.palette[((1.0 - brightness) * (self.palette.len() - 1) as f32) as usize]);
}
ray_dir -= step_h * WIDTH as f32;
addstr(&row);
}
}
pub fn normal(&self, point: Vector) -> Vector {
let d = 0.001;
let dx = Vector::unit_x() * d;
let dy = Vector::unit_y() * d;
let dz = Vector::unit_z() * d;
let sdf = self.sdf(point);
return (Vector {
x: (self.sdf(point + dx) - sdf),
y: (self.sdf(point + dy) - sdf),
z: (self.sdf(point + dz) - sdf),
} / d).normalize()
}
pub fn ray_marching(&self, origin: Vector, direction: Vector) -> Option<Vector> {
let threshold = 0.1;
let ray = direction.normalize();
let mut point = origin;
let mut dist = 0.0;
let mut count = 0;
while dist < 8.0 && count < 10 {
count += 1;
dist = self.sdf(point);
if dist.abs() < threshold {
return Some(point);
}
point += ray * dist;
}
return None
}
pub fn light_point(&self, point: Vector) -> f32 {
let ambient = 0.1;
return ambient + (1.0 - ambient) * (self.diffuse_lighting(point) * 0.7 + self.specular_lighting(point) * 0.3)
}
pub fn diffuse_lighting(&self, point: Vector) -> f32 {
let mut res: f32 = 1.0;
let mut t = 0.1;
let k = 4.0;
while t < 1.0 {
let h = self.sdf(point - self.light * t);
if h < 0.001 {
return 0.00
}
res = res.min(k * h / t);
t += h;
}
return res
}
pub fn specular_lighting(&self, point: Vector) -> f32 {
let normal = self.normal(point);
let dot = -(normal.dot(self.light));
return dot.min(1.0).max(0.0)
}
}
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