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spheres: implement rtiow Sphere::intersect for comparison.

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This commit is contained in:
Bill Thiede 2021-07-18 16:29:45 -07:00
parent 19b2ef6ded
commit 37048ddd52
1 changed files with 24 additions and 6 deletions
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30
rtchallenge/src/spheres.rs
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@ -193,6 +193,10 @@ impl Sphere {
/// assert_eq!(xs.len(), 0);
/// ```
pub fn intersect<'s>(sphere: &'s Sphere, ray: &Ray) -> Intersections<'s> {
intersect_rtc(sphere, ray)
}
fn intersect_rtc<'s>(sphere: &'s Sphere, ray: &Ray) -> Intersections<'s> {
let ray = ray.transform(sphere.inverse_transform);
let sphere_to_ray = ray.origin - Tuple::point(0., 0., 0.);
let a = dot(ray.direction, ray.direction);
@ -200,11 +204,25 @@ pub fn intersect<'s>(sphere: &'s Sphere, ray: &Ray) -> Intersections<'s> {
let c = dot(sphere_to_ray, sphere_to_ray) - 1.;
let discriminant = b * b - 4. * a * c;
if discriminant < 0. {
Intersections::default()
} else {
Intersections::new(vec![
Intersection::new((-b - discriminant.sqrt()) / (2. * a), &sphere),
Intersection::new((-b + discriminant.sqrt()) / (2. * a), &sphere),
])
return Intersections::default();
}
Intersections::new(vec![
Intersection::new((-b - discriminant.sqrt()) / (2. * a), &sphere),
Intersection::new((-b + discriminant.sqrt()) / (2. * a), &sphere),
])
}
fn intersect_rtiow<'s>(sphere: &'s Sphere, ray: &Ray) -> Intersections<'s> {
let ray = ray.transform(sphere.inverse_transform);
let oc = ray.origin - Tuple::point(0., 0., 0.);
let a = dot(ray.direction, ray.direction);
let b = dot(oc, ray.direction);
let c = dot(oc, oc) - 1.;
let discriminant = b * b - a * c;
if discriminant < 0. {
return Intersections::default();
}
Intersections::new(vec![
Intersection::new((-b - discriminant.sqrt()) / a, &sphere),
Intersection::new((-b + discriminant.sqrt()) / a, &sphere),
])
}