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use cgmath::Matrix3;
use cgmath::Vector3;
use cgmath::prelude::*;
use std::fmt;
type Vector = Vector3<f32>;
pub const HEIGHT: i32 = 30;
pub const WIDTH: i32 = HEIGHT * 3;
#[derive(Debug)]
pub struct Buffer (pub [[char; WIDTH as usize]; HEIGHT as usize]);
impl fmt::Display for Buffer {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for i in 0..HEIGHT as usize {
for j in 0..WIDTH as usize {
write!(f, "{}", self.0[i][j])?;
}
writeln!(f)?;
}
write!(f, "")
}
}
#[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 buffer: Buffer,
pub speed: f32,
pub turn_rate: f32,
}
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 sphere(point: Vector, center: Vector, radius: f32) -> f32 {
(point - center).magnitude() - radius
}
fn r#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 sdf(&self, point: Vector) -> f32 {
let mut dist: f32;
// Floor at z = -2
let floor_dist = point.z + 1.0;
dist = floor_dist;
// Sphere
{
let center = Vector { x: 4.0, y: 0.0, z: 0.0 };
let radius = 1.5;
dist = softmin(dist, sphere(point, center, radius), 1.2);
}
// Hole
{
let center = Vector { x: 4.0, y: 0.0, z: 0.0 };
let size = Vector::new(5.0, 2.0, 2.0);
dist = dist.max(-r#box(point, center, size));
}
// Windows
{
let center = Vector { x: 4.0, y: 0.0, z: 0.0 };
let size = Vector::new(1.0, 5.0, 1.0);
dist = dist.max(-(r#box(point, center, size)));
}
return dist
}
pub fn screen(&self) -> (f32, f32) {
let width = self.distance * 2.0 * (self.angle / 2.0).tan();
let height = width * self.aspect_ratio;
// println!("Screen {}x{} units", width, height);
(width, height)
}
pub fn render(& mut self) {
let palette = "$@B%8&WM#oahkbdpqwmZO0QLCJUYXzcvunxrjft/\\|()1{}[]?-_+~<>i!lI;:,\"^`'. ".to_string();
let (screen_width, screen_height) = self.screen();
let cross = self.up.cross(self.direction);
// 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,
cross * screen_width,
self.up * screen_height,
);
for i in 0..HEIGHT as usize {
let ix = i as f32 / HEIGHT as f32;
for j in 0..WIDTH as usize {
let jx = j as f32 / WIDTH as f32;
// Apply transform to unit square centered at (1, 0, 0)
let ray_dir = operator * Vector { x: 1.0, y: 0.5 - jx, z: 0.5 - ix };
let collision = self.ray_marching(self.position, ray_dir);
let brightness = match collision {
Some(point) => self.light_point(point),
None => 0.0
};
self.buffer.0[i][j] = palette
.chars()
.nth(((1.0 - brightness) * (palette.len() - 1) as f32) as usize)
.unwrap();
}
}
}
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;
return (Vector {
x: (self.sdf(point + dx) - self.sdf(point - dx)),
y: (self.sdf(point + dy) - self.sdf(point - dy)),
z: (self.sdf(point + dz) - self.sdf(point - dz)),
} / (2.0 * 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 < 10.0 && count < 30 {
count += 1;
dist = self.sdf(point);
if dist < 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 ph = 1e20;
let mut t = 0.1;
let k = 4.0;
while t < 7.0 {
let h = self.sdf(point - self.light * t);
if h < 0.001 {
return 0.00
}
let y = h * h / (2.0 * ph);
let d = (h * h - y * y).sqrt();
res = res.min(k * d / (t - y).max(0.0));
t += h;
ph = 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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