Struct cgmath::Basis2

pub struct Basis2<S> {
    // some fields omitted
}

A two-dimensional rotation matrix.

The matrix is guaranteed to be orthogonal, so some operations can be implemented more efficiently than the implementations for math::Matrix2. To enforce orthogonality at the type level the operations have been restricted to a subset of those implemented on Matrix2.

Example

Suppose we want to rotate a vector that lies in the x-y plane by some angle. We can accomplish this quite easily with a two-dimensional rotation matrix:

use cgmath::rad;
use cgmath::Vector2;
use cgmath::{Matrix, Matrix2};
use cgmath::{Rotation, Rotation2, Basis2};
use cgmath::ApproxEq;
use std::f64;

// For simplicity, we will rotate the unit x vector to the unit y vector --
// so the angle is 90 degrees, or π/2.
let unit_x: Vector2<f64> = Vector2::unit_x();
let rot: Basis2<f64> = Rotation2::from_angle(rad(0.5f64 * f64::consts::PI));

// Rotate the vector using the two-dimensional rotation matrix:
let unit_y = rot.rotate_vector(unit_x);

// Since sin(π/2) may not be exactly zero due to rounding errors, we can
// use cgmath's approx_eq() feature to show that it is close enough.
assert!(unit_y.approx_eq(&Vector2::unit_y()));

// This is exactly equivalent to using the raw matrix itself:
let unit_y2: Matrix2<_> = rot.into();
let unit_y2 = unit_y2 * unit_x;
assert_eq!(unit_y2, unit_y);

// Note that we can also concatenate rotations:
let rot_half: Basis2<f64> = Rotation2::from_angle(rad(0.25f64 * f64::consts::PI));
let unit_y3 = (rot_half * rot_half).rotate_vector(unit_x);
assert!(unit_y3.approx_eq(&unit_y2));

Trait Implementations

impl<S: Clone> Clone for Basis2<S>

fn clone(&self) -> Basis2<S>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<S: Copy> Copy for Basis2<S>

impl<S: PartialEq> PartialEq for Basis2<S>

fn eq(&self, __arg_0: &Basis2<S>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, __arg_0: &Basis2<S>) -> bool

This method tests for !=.

impl<S: Decodable> Decodable for Basis2<S>

fn decode<__DS: Decoder>(__arg_0: &mut __DS) -> Result<Basis2<S>, __DS::Error>

impl<S: Encodable> Encodable for Basis2<S>

fn encode<__SS: Encoder>(&self, __arg_0: &mut __SS) -> Result<(), __SS::Error>

impl<S: BaseFloat> AsRef<Matrix2<S>> for Basis2<S>

fn as_ref(&self) -> &Matrix2<S>

Performs the conversion.

impl<S: BaseFloat> Rotation<Point2<S>> for Basis2<S>

fn look_at(dir: Vector2<S>, up: Vector2<S>) -> Basis2<S>

Create a rotation to a given direction with an 'up' vector

fn between_vectors(a: Vector2<S>, b: Vector2<S>) -> Basis2<S>

Create a shortest rotation to transform vector 'a' into 'b'. Both given vectors are assumed to have unit length.

fn rotate_vector(&self, vec: Vector2<S>) -> Vector2<S>

Rotate a vector using this rotation.

fn invert(&self) -> Basis2<S>

Create a new rotation which "un-does" this rotation. That is, r * r.invert() is the identity.

fn rotate_point(&self, point: P) -> P

Rotate a point using this rotation, by converting it to its representation as a vector.

impl<S: BaseFloat> One for Basis2<S>

fn one() -> Basis2<S>

Returns the multiplicative identity element of Self, 1.

impl<S: BaseFloat> Mul<Basis2<S>> for Basis2<S>

type Output = Basis2<S>

The resulting type after applying the * operator

fn mul(self, other: Basis2<S>) -> Basis2<S>

The method for the * operator

impl<'a, S: BaseFloat> Mul<&'a Basis2<S>> for Basis2<S>

type Output = Basis2<S>

The resulting type after applying the * operator

fn mul(self, other: &'a Basis2<S>) -> Basis2<S>

The method for the * operator

impl<'a, S: BaseFloat> Mul<Basis2<S>> for &'a Basis2<S>

type Output = Basis2<S>

The resulting type after applying the * operator

fn mul(self, other: Basis2<S>) -> Basis2<S>

The method for the * operator

impl<'a, 'b, S: BaseFloat> Mul<&'a Basis2<S>> for &'b Basis2<S>

type Output = Basis2<S>

The resulting type after applying the * operator

fn mul(self, other: &'a Basis2<S>) -> Basis2<S>

The method for the * operator

impl<S: BaseFloat> ApproxEq for Basis2<S>

type Epsilon = S

fn approx_eq_eps(&self, other: &Basis2<S>, epsilon: &S) -> bool

fn approx_epsilon() -> Self::Epsilon

fn approx_eq(&self, other: &Self) -> bool

impl<S: BaseFloat> Rotation2<S> for Basis2<S>

fn from_angle(theta: Rad<S>) -> Basis2<S>

Create a rotation by a given angle. Thus is a redundant case of both from_axis_angle() and from_euler() for 2D space.

impl<S: Debug> Debug for Basis2<S>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.