1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

use std::f32;

use linalg::{Point, Vector};

/// Ray is a standard 3D ray, starting at origin `o` and heading in direction `d`
/// The min and max points along the ray can be specified with `min_t` and `max_t`
/// `depth` is the recursion depth of the ray
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct Ray {
    /// Origin of the ray
    pub o: Point,
    /// Direction the ray is heading
    pub d: Vector,
    /// Point along the ray that the actual ray starts at, `p = o + min_t * d`
    pub min_t: f32,
    /// Point along the ray at which it stops, will be inf if the ray is infinite
    pub max_t: f32,
    /// Recursion depth of the ray
    pub depth: u32,
    /// Time point sampled by this ray
    pub time: f32,
}

impl Ray {
    /// Create a new ray from `o` heading in `d` with infinite length
    pub fn new(o: &Point, d: &Vector, time: f32) -> Ray {
        Ray { o: *o, d: *d, min_t: 0f32, max_t: f32::INFINITY, depth: 0, time: time }
    }
    /// Create a new segment ray from `o + min_t * d` to `o + max_t * d`
    pub fn segment(o: &Point, d: &Vector, min_t: f32, max_t: f32, time: f32) -> Ray {
        Ray { o: *o, d: *d, min_t: min_t, max_t: max_t, depth: 0, time: time }
    }
    /// Create a child ray from the parent starting at `o` and heading in `d`
    pub fn child(&self, o: &Point, d: &Vector) -> Ray {
        Ray { o: *o, d: *d, min_t: 0f32, max_t: f32::INFINITY, depth: self.depth + 1, time: self.time }
    }
    /// Create a child ray segment from `o + min_t * d` to `o + max_t * d`
    pub fn child_segment(&self, o: &Point, d: &Vector, min_t: f32, max_t: f32) -> Ray {
        Ray { o: *o, d: *d, min_t: min_t, max_t: max_t, depth: self.depth + 1, time: self.time }
    }
    /// Evaulate the ray equation at some t value and return the point
    /// returns result of `self.o + t * self.d`
    pub fn at(&self, t: f32) -> Point {
        self.o + self.d * t
    }
}