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use cgmath::Vector3;
use cgmath::prelude::*;
use ncurses::addstr;
use std::f32;
use crate::Buffer;
use crate::Camera;
type Vector = Vector3<f32>;
pub struct Renderer {
pub camera: Camera,
pub buffer: Buffer,
}
impl Renderer {
pub fn render(&self, sdf: &dyn Fn(Vector) -> f32) {
let (mut ray_dir, mut step_h, mut step_v) = self.camera.get_screen_iterator();
step_v /= self.buffer.height;
step_h /= self.buffer.width;
for _i in 0..self.buffer.height as usize {
ray_dir += step_v;
let mut row = "\n".to_string();
for _j in 0..self.buffer.width as usize {
ray_dir += step_h;
let collision = Self::ray_march(self.camera.position, ray_dir, sdf);
let brightness = match collision {
Some(point) => Self::light_point(point, sdf),
None => 0.0
};
row.push(self.buffer.palette[((1.0 - brightness) * (self.buffer.palette.len() - 1) as f32) as usize]);
}
ray_dir -= step_h * self.buffer.width;
addstr(&row);
}
}
pub fn ray_march(origin: Vector, direction: Vector, sdf: &dyn Fn(Vector) -> f32) -> 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 = sdf(point);
if dist.abs() < threshold {
return Some(point);
}
point += ray * dist;
}
return None
}
pub fn light_point(point: Vector, sdf: &dyn Fn(Vector) -> f32) -> f32 {
let light = Vector::new(1.0, 1.0, -1.0);
let ambient = 0.1;
return ambient + (1.0 - ambient) * (
Self::diffuse_lighting(point, light, sdf) * 0.7 +
Self::specular_lighting(point, light, sdf) * 0.3
)
}
pub fn diffuse_lighting(point: Vector, light: Vector, sdf: &dyn Fn(Vector) -> f32) -> f32 {
let mut res: f32 = 1.0;
let mut t = 0.1;
let k = 4.0;
while t < 1.0 {
let h = sdf(point - light * t);
if h < 0.001 {
return 0.00
}
res = res.min(k * h / t);
t += h;
}
return res
}
pub fn specular_lighting(point: Vector, light: Vector, sdf: &dyn Fn(Vector) -> f32) -> f32 {
let normal = Self::normal(point, sdf);
let dot = -(normal.dot(light));
return dot.min(1.0).max(0.0)
}
pub fn normal(point: Vector, sdf: &dyn Fn(Vector) -> f32) -> Vector {
let d = 0.001;
let dx = Vector::unit_x() * d;
let dy = Vector::unit_y() * d;
let dz = Vector::unit_z() * d;
let dist = sdf(point);
return (Vector {
x: (sdf(point + dx) - dist),
y: (sdf(point + dy) - dist),
z: (sdf(point + dz) - dist),
} / d).normalize()
}
}
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