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transformations: moving another doctest to unit

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This commit is contained in:
Bill Thiede 2021-07-30 21:58:32 -07:00
parent 1c2caf2cc5
commit c882fc81e5
1 changed files with 53 additions and 41 deletions
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94
rtchallenge/src/transformations.rs
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@ -5,47 +5,6 @@ use crate::{
/// Create a matrix representing a eye at `from` looking at `to`, with an `up`
/// as the up vector.
///
/// # Examples
/// ```
/// use rtchallenge::{matrices::Matrix4x4, transformations::view_transform, tuples::Tuple};
///
/// // The transofrmation matrix for the default orientation.
/// let from = Tuple::point(0., 0., 0.);
/// let to = Tuple::point(0., 0., -1.);
/// let up = Tuple::vector(0., 1., 0.);
/// let t = view_transform(from, to, up);
/// assert_eq!(t, Matrix4x4::identity());
///
/// // A view transformation matrix looking in positive z direction.
/// let from = Tuple::point(0., 0., 0.);
/// let to = Tuple::point(0., 0., 1.);
/// let up = Tuple::vector(0., 1., 0.);
/// let t = view_transform(from, to, up);
/// assert_eq!(t, Matrix4x4::scaling(-1., 1., -1.));
///
/// // The view tranformation moves the world.
/// let from = Tuple::point(0., 0., 8.);
/// let to = Tuple::point(0., 0., 0.);
/// let up = Tuple::vector(0., 1., 0.);
/// let t = view_transform(from, to, up);
/// assert_eq!(t, Matrix4x4::translation(0., 0., -8.));
///
/// // An arbitrary view transformation.
/// let from = Tuple::point(1., 3., 2.);
/// let to = Tuple::point(4., -2., 8.);
/// let up = Tuple::vector(1., 1., 0.);
/// let t = view_transform(from, to, up);
/// assert_eq!(
/// t,
/// Matrix4x4::new(
/// [-0.50709, 0.50709, 0.67612, -2.36643],
/// [0.76772, 0.60609, 0.12122, -2.82843],
/// [-0.35857, 0.59761, -0.71714, 0.],
/// [0., 0., 0., 1.],
/// )
/// );
/// ```
pub fn view_transform(from: Tuple, to: Tuple, up: Tuple) -> Matrix4x4 {
let forward = (to - from).normalize();
let left = cross(forward, up.normalize());
@ -57,3 +16,56 @@ pub fn view_transform(from: Tuple, to: Tuple, up: Tuple) -> Matrix4x4 {
[0., 0., 0., 1.],
) * Matrix4x4::translation(-from.x, -from.y, -from.z)
}
#[cfg(test)]
mod tests {
use crate::{
matrices::{identity, scaling, translation, Matrix4x4},
transformations::view_transform,
tuples::{point, vector},
};
#[test]
fn default_orientation() {
// The transformation matrix for the default orientation.
let from = point(0., 0., 0.);
let to = point(0., 0., -1.);
let up = vector(0., 1., 0.);
let t = view_transform(from, to, up);
assert_eq!(t, identity());
}
#[test]
fn looking_positive_z() {
// A view transformation matrix looking in positive z direction.
let from = point(0., 0., 0.);
let to = point(0., 0., 1.);
let up = vector(0., 1., 0.);
let t = view_transform(from, to, up);
assert_eq!(t, scaling(-1., 1., -1.));
}
#[test]
fn transformation_moves_world() {
// The view transformation moves the world.
let from = point(0., 0., 8.);
let to = point(0., 0., 0.);
let up = vector(0., 1., 0.);
let t = view_transform(from, to, up);
assert_eq!(t, translation(0., 0., -8.));
}
#[test]
fn arbitrary_view() {
// An arbitrary view transformation.
let from = point(1., 3., 2.);
let to = point(4., -2., 8.);
let up = vector(1., 1., 0.);
let t = view_transform(from, to, up);
assert_eq!(
t,
Matrix4x4::new(
[-0.50709, 0.50709, 0.67612, -2.36643],
[0.76772, 0.60609, 0.12122, -2.82843],
[-0.35857, 0.59761, -0.71714, 0.],
[0., 0., 0., 1.],
)
);
}
}