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use cgmath::Vector3;
use cgmath::prelude::*;
use std::{cmp::{max, min}, f32::consts::PI, fmt};
type Vector = Vector3<f32>;
pub fn rotate_z(vec: Vector, angle: f32) -> Vector {
return Vector {
x: vec.x * angle.cos() + vec.y * angle.sin(),
y: vec.y * angle.cos() - vec.x * angle.sin(),
z: vec.z,
}
}
pub const HEIGHT: i32 = 40;
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 angle: f32,
pub distance: f32,
pub brightness: f32,
pub aspect_ratio: f32,
pub buffer: Buffer,
}
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;:,\"^`'. ";
let (screen_width, screen_height) = self.screen();
let h_step = rotate_z(self.direction, PI / 2.0).normalize() * screen_width / WIDTH as f32;
let v_step = Vector { x: 0.0, y: 0.0, z: -screen_height / HEIGHT as f32 };
// println!("Steps: h{}, v{}", h_step, v_step);
// Initialize with a corner
let point = self.position + (self.direction.normalize() * self.distance) - (h_step * (WIDTH / 2) as f32 + v_step * (HEIGHT / 2) as f32);
// println!("Corner: {}", point);
let mut ray_dir = point - self.position;
for i in 0..HEIGHT as usize {
ray_dir = ray_dir + v_step;
for j in 0..WIDTH as usize {
ray_dir = ray_dir + h_step;
let brightness = self.shoot_ray(ray_dir);
self.buffer.0[i][j] = palette.chars().nth((brightness * palette.len() as f32) as usize - 1).unwrap();
// println!("[{}, {}]: {}", i, j, ray_dir);
}
ray_dir = ray_dir - h_step * WIDTH as f32;
}
}
pub fn normal(&self, point: Vector) -> Vector {
let d = 0.01;
let dx = Vector { x: d, y: 0.0, z: 0.0 };
let dfdx = (self.sdf(point + dx) - self.sdf(point - dx)) / (2.0 * d);
let dy = Vector { x: 0.0, y: d, z: 0.0 };
let dfdy = (self.sdf(point + dy) - self.sdf(point - dy)) / (2.0 * d);
let dz = Vector { x: 0.0, y: 0.0, z: d };
let dfdz = (self.sdf(point + dz) - self.sdf(point - dz)) / (2.0 * d);
Vector { x: dfdx, y: dfdy, z: dfdz }.normalize()
}
pub fn shoot_ray(&self, direction: Vector) -> f32 {
let light = Vector { x: 1.0, y: 1.0, z: -1.0 }.normalize();
let threshold = 0.1;
let ray = direction.normalize();
let mut point = self.position;
let mut dist = 0.0;
let mut count = 0;
while dist < self.brightness && count < 50 {
count += 1;
dist = self.sdf(point);
if dist < threshold {
// Collision in point! Let's calculate lights now:
let mut res: f32 = 1.0;
let mut t = 0.001;
let k = 2.0;
while t < 7.0 {
let h = self.sdf(point - light * t);
if h < 0.001 {
return 0.97
}
res = res.min(k * h / t);
t += h;
}
let normal = self.normal(point);
let dot = -(normal.dot(light));
return 1.0 - 0.5 * dot.max(0.01).min(0.98) - 0.5 * res.min(0.98)
}
point = point + ray * dist;
}
return 1.0
}
}
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