in layer.rs file, we trace ray!!!
pub fn set_data(&mut self) {
let [width, height] = self.vp_size;
unsafe {
// A redundant loop to demonstrate reading image data
for y in 0..height as u32 {
for x in 0..width as u32 {
let pixel = (*self.imgbuf).get_pixel_mut(x, y);
let u = coord_to_color(x, width);
let v = coord_to_color(y, height);
*pixel = self.per_pixel(u, v);
}
}
}
}$ t = \sqrt ( b ^ 2 - 4 * a * c ) $
pub fn per_pixel(
&mut self,
x: f32,
y: f32,
) -> Rgb<u8> {
let (u, v) = ((x + 1.0) / 2.0, (y + 1.0) / 2.0);
// pixel color for multisampling
for sphere in &self.world {
let mut pixel_color = Rgb([0_u8, 0_u8, 0_u8]);
// multisampling
for _s in 0..100 {
// FIXME: include random (-1.0 - 1.0)
let su = u + 0.010;
let sv = v + 0.010;
let mut ray = self.camera.get_ray(su, sv);
let root = Self::trace_ray(&mut ray, *sphere, 0.0, num::Float::max_value());
let hit = Self::get_ray_hit(&mut ray, *sphere, root);
let nn = hit.n.normalize();
let ray_color = rgb8_from_vec3([nn.x, nn.y, nn.z]);
pixel_color = plus_rgb8(pixel_color, ray_color);
let background_color = rgb8_from_vec3([x, y, 50.0]);
if hit.t >= 0.0 {
return pixel_color;
} else {
return background_color;
}
}
}
// when world is empty
rgb8_from_vec3([0.0, 0.0, 0.0])
} pub fn trace_ray(
ray: &Ray,
sphere: Sphere,
tmin: f32,
tmax: f32,
) -> f32 {
let oc = ray.origin - sphere.center.xyz();
let a = dot(&ray.direction, &ray.direction);
let half_b = dot(&oc, &ray.direction);
let c = dot(&oc, &oc) - sphere.radius * sphere.radius;
let discriminant = half_b * half_b - a * c;
if discriminant > 0.0 {
// closet T
let mut root = (-half_b - num::Float::sqrt(discriminant)) / a;
if root < tmax && root > tmin {
return root;
}
// farest T
root = (-half_b + num::Float::sqrt(discriminant)) / a;
if root < tmax && root > tmin {
return root;
}
}
return -1.0;
}assets/moon.jpeg
- NASA's Scientific Visualization Studio
- https://svs.gsfc.nasa.gov/4720
assets/earthmap.jpeg
formula
$ \sin (\theta) + \cos () $