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spheres: cache inverse transform to accelerate normal_at.

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This commit is contained in:
Bill Thiede 2021-07-17 23:10:54 -07:00
parent 5f3bfd744e
commit 2395c96e01
4 changed files with 46 additions and 30 deletions
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5
rtchallenge/examples/eoc5.rs
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@ -20,8 +20,9 @@ fn main() -> Result<()> {
let half = wall_size / 2.;
let color = Color::new(1., 0., 0.);
let mut shape = Sphere::default();
shape.transform =
Matrix4x4::shearing(1., 0., 0., 0., 0., 0.) * Matrix4x4::scaling(0.5, 1., 1.0);
shape.set_transform(
Matrix4x4::shearing(1., 0., 0., 0., 0., 0.) * Matrix4x4::scaling(0.5, 1., 1.0),
);
for y in 0..h {
let world_y = half - pixel_size * y as f32;

27
rtchallenge/examples/eoc7.rs
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@ -16,8 +16,8 @@ use rtchallenge::{
fn main() -> Result<()> {
let start = Instant::now();
let width = 640;
let height = 480;
let width = 1024;
let height = 1024;
let light_position = Tuple::point(-10., 10., -10.);
let light_color = WHITE;
let light = PointLight::new(light_position, light_color);
@ -28,7 +28,7 @@ fn main() -> Result<()> {
camera.transform = view_transform(from, to, up);
let mut floor = Sphere::default();
floor.transform = Matrix4x4::scaling(10., 0.01, 10.);
floor.set_transform(Matrix4x4::scaling(10., 0.01, 10.));
floor.material = Material {
color: Color::new(1., 0.9, 0.9),
specular: 0.,
@ -36,21 +36,25 @@ fn main() -> Result<()> {
};
let mut left_wall = Sphere::default();
left_wall.transform = Matrix4x4::translation(0., 0., 5.)
left_wall.set_transform(
Matrix4x4::translation(0., 0., 5.)
* Matrix4x4::rotation_y(-PI / 4.)
* Matrix4x4::rotation_x(PI / 2.)
* Matrix4x4::scaling(10., 0.01, 10.);
* Matrix4x4::scaling(10., 0.01, 10.),
);
left_wall.material = floor.material.clone();
let mut right_wall = Sphere::default();
right_wall.transform = Matrix4x4::translation(0., 0., 5.)
right_wall.set_transform(
Matrix4x4::translation(0., 0., 5.)
* Matrix4x4::rotation_y(PI / 4.)
* Matrix4x4::rotation_x(PI / 2.)
* Matrix4x4::scaling(10., 0.01, 10.);
* Matrix4x4::scaling(10., 0.01, 10.),
);
right_wall.material = floor.material.clone();
let mut middle = Sphere::default();
middle.transform = Matrix4x4::translation(-0.5, 1., 0.5);
middle.set_transform(Matrix4x4::translation(-0.5, 1., 0.5));
middle.material = Material {
color: Color::new(0.1, 1., 0.5),
diffuse: 0.7,
@ -59,7 +63,7 @@ fn main() -> Result<()> {
};
let mut right = Sphere::default();
right.transform = Matrix4x4::translation(1.5, 0.5, -0.5) * Matrix4x4::scaling(0.5, 0.5, 0.5);
right.set_transform(Matrix4x4::translation(1.5, 0.5, -0.5) * Matrix4x4::scaling(0.5, 0.5, 0.5));
right.material = Material {
color: Color::new(0.5, 1., 0.1),
diffuse: 0.7,
@ -68,8 +72,9 @@ fn main() -> Result<()> {
};
let mut left = Sphere::default();
left.transform =
Matrix4x4::translation(-1.5, 0.33, -0.75) * Matrix4x4::scaling(0.33, 0.33, 0.33);
left.set_transform(
Matrix4x4::translation(-1.5, 0.33, -0.75) * Matrix4x4::scaling(0.33, 0.33, 0.33),
);
left.material = Material {
color: Color::new(1., 0.8, 0.1),
diffuse: 0.7,

34
rtchallenge/src/spheres.rs
View File

@ -6,11 +6,12 @@ use crate::{
tuples::{dot, Tuple},
};
#[derive(Debug, PartialEq)]
#[derive(Debug, PartialEq, Clone)]
/// Sphere represents the unit-sphere (radius of unit 1.) at the origin 0., 0., 0.
pub struct Sphere {
// TODO(wathiede): cache inverse to speed up intersect.
pub transform: Matrix4x4,
transform: Matrix4x4,
inverse_transform: Matrix4x4,
pub material: Material,
}
@ -21,13 +22,13 @@ impl Default for Sphere {
///
/// // A sphere's default transform is the identity matrix.
/// let s = Sphere::default();
/// assert_eq!(s.transform, Matrix4x4::identity());
/// assert_eq!(s.transform(), Matrix4x4::identity());
///
/// // It can be changed by directly setting the transform member.
/// let mut s = Sphere::default();
/// let t = Matrix4x4::translation(2., 3., 4.);
/// s.transform = t.clone();
/// assert_eq!(s.transform, t);
/// s.set_transform ( t.clone());
/// assert_eq!(s.transform(), t);
///
/// // Default Sphere has the default material.
/// assert_eq!(s.material, Material::default());
@ -42,6 +43,7 @@ impl Default for Sphere {
fn default() -> Sphere {
Sphere {
transform: Matrix4x4::identity(),
inverse_transform: Matrix4x4::identity(),
material: Material::default(),
}
}
@ -91,7 +93,7 @@ impl Sphere {
///
/// // Compute the normal on a translated sphere.
/// let mut s = Sphere::default();
/// s.transform = Matrix4x4::translation(0., 1., 0.);
/// s.set_transform ( Matrix4x4::translation(0., 1., 0.));
/// let n = s.normal_at(Tuple::point(0., 1.70711, -0.70711));
/// assert_eq!(n, Tuple::vector(0., 0.70711, -0.70711));
@ -99,17 +101,25 @@ impl Sphere {
/// use std::f32::consts::PI;
///
/// let mut s = Sphere::default();
/// s.transform = Matrix4x4::scaling(1.,0.5,1.) * Matrix4x4::rotation_z(PI/5.);
/// s.set_transform ( Matrix4x4::scaling(1.,0.5,1.) * Matrix4x4::rotation_z(PI/5.));
/// let n = s.normal_at(Tuple::point(0., 2_f32.sqrt()/2., -2_f32.sqrt()/2.));
/// assert_eq!(n, Tuple::vector(0., 0.97014, -0.24254));
/// ```
pub fn normal_at(&self, world_point: Tuple) -> Tuple {
let object_point = self.transform.inverse() * world_point;
let object_point = self.inverse_transform * world_point;
let object_normal = object_point - Tuple::point(0., 0., 0.);
let mut world_normal = self.transform.inverse().transpose() * object_normal;
let mut world_normal = self.inverse_transform.transpose() * object_normal;
world_normal.w = 0.;
world_normal.normalize()
}
pub fn transform(&self) -> Matrix4x4 {
self.transform
}
pub fn set_transform(&mut self, t: Matrix4x4) {
self.transform = t;
self.inverse_transform = t.inverse();
}
}
/// Intersect a ray with a sphere.
@ -160,7 +170,7 @@ impl Sphere {
/// // Intersect a scaled sphere with a ray.
/// let r = Ray::new(Tuple::point(0., 0., -5.), Tuple::vector(0., 0., 1.));
/// let mut s = Sphere::default();
/// s.transform = Matrix4x4::scaling(2., 2., 2.);
/// s.set_transform(Matrix4x4::scaling(2., 2., 2.));
/// let xs = intersect(&s, &r);
/// assert_eq!(xs.len(), 2, "xs {:?}", xs);
/// assert_eq!(xs[0].t, 3., "xs {:?}", xs);
@ -169,12 +179,12 @@ impl Sphere {
/// // Intersect a translated sphere with a ray.
/// let r = Ray::new(Tuple::point(0., 0., -5.), Tuple::vector(0., 0., 1.));
/// let mut s = Sphere::default();
/// s.transform = Matrix4x4::translation(5., 0., 0.);
/// s.set_transform(Matrix4x4::translation(5., 0., 0.));
/// let xs = intersect(&s, &r);
/// assert_eq!(xs.len(), 0);
/// ```
pub fn intersect<'s>(sphere: &'s Sphere, ray: &Ray) -> Intersections<'s> {
let ray = ray.transform(sphere.transform.inverse());
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);
let b = 2. * dot(ray.direction, sphere_to_ray);

2
rtchallenge/src/world.rs
View File

@ -48,7 +48,7 @@ impl World {
..Material::default()
};
let mut s2 = Sphere::default();
s2.transform = Matrix4x4::scaling(0.5, 0.5, 0.5);
s2.set_transform(Matrix4x4::scaling(0.5, 0.5, 0.5));
World {
light: Some(light),
objects: vec![s1, s2],