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//! # Spatial
//!
//! The `spatial` module provides the [`Vec2`] struct to specify positions on the terminal screen
//! and the [`Direction`] enum to specify and provide utility methods for relative directions.
use num::cast::ToPrimitive;
use std::cmp::Ordering;
use std::convert::TryFrom;
use std::error::Error;
use std::fmt;
use std::fmt::{Display, Formatter};
use std::ops::{
Add, AddAssign, Div, DivAssign, Index, IndexMut, Mul, MulAssign, Neg, Sub, SubAssign,
};
/// Represents a two-dimensional spatial vector.
///
/// It is generally used as a position vector, representing a point on the
/// [`Canvas`](crate::terminal::Canvas). In the terminal, the origin is (by default) set at the
/// top-left corner with `y` increasing downwards, i.e., counting from top to bottom.
///
/// At times, it is also used as a size. The differences are shown in the example below.
///
/// ## Example
///
/// ```rust
/// # use ruscii::spatial::Vec2;
/// # use ruscii::terminal::{Canvas, VisualElement};
/// #
/// let mut canvas = Canvas::new(
/// Vec2::xy(20, 20), // (20, 20) is used as a size here.
/// &VisualElement::default()
/// );
/// let a = Vec2::xy(20, 20); // (20, 20) is used as a position here
/// let b = Vec2::xy(19, 19); // and (19, 19) as a position here.
///
/// assert!(canvas.contains(b)); // b is a valid point on the Canvas.
/// assert!(!canvas.contains(a)); // The bottom-right corner is actually (19, 19).
/// ```
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct Vec2 {
pub x: i32,
pub y: i32,
}
impl Vec2 {
/// Constructs a [`Vec2`] representing (0, 0).
pub fn zero() -> Vec2 {
Vec2 { x: 0, y: 0 }
}
/// Constructs a [`Vec2`] with the given `x`- and `y`-coordinates.
pub fn xy<T1: ToPrimitive, T2: ToPrimitive>(x: T1, y: T2) -> Vec2 {
Vec2 {
x: x.to_i32().unwrap(),
y: y.to_i32().unwrap(),
}
}
/// Constructs a [`Vec2`] with the given `x`-coordinate and a `y`-coordinate of 0.
pub fn x<T: ToPrimitive>(x: T) -> Vec2 {
Vec2 {
x: x.to_i32().unwrap(),
y: 0,
}
}
/// Constructs a [`Vec2`] with the given `y`-coordinate and an `x`-coordinate of 0.
pub fn y<T: ToPrimitive>(y: T) -> Vec2 {
Vec2 {
x: 0,
y: y.to_i32().unwrap(),
}
}
/// Sets the [`Vec2`] object to (0, 0).
pub fn clear(&mut self) {
self.x = 0;
self.y = 0;
}
}
impl Display for Vec2 {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(f, "({}, {})", self.x, self.y)
}
}
impl Add for Vec2 {
type Output = Vec2;
fn add(self, other: Vec2) -> Vec2 {
Vec2 {
x: self.x + other.x,
y: self.y + other.y,
}
}
}
impl Sub for Vec2 {
type Output = Vec2;
fn sub(self, other: Vec2) -> Vec2 {
Vec2 {
x: self.x - other.x,
y: self.y - other.y,
}
}
}
impl Mul for Vec2 {
type Output = Vec2;
fn mul(self, other: Vec2) -> Vec2 {
Vec2 {
x: self.x * other.x,
y: self.y * other.y,
}
}
}
impl Div for Vec2 {
type Output = Vec2;
fn div(self, other: Vec2) -> Vec2 {
Vec2 {
x: self.x / other.x,
y: self.y / other.y,
}
}
}
impl<T: ToPrimitive> Mul<T> for Vec2 {
type Output = Vec2;
fn mul(self, scalar: T) -> Vec2 {
let scalar = scalar.to_i32().unwrap();
Vec2 {
x: self.x * scalar,
y: self.y * scalar,
}
}
}
impl<T: ToPrimitive> Div<T> for Vec2 {
type Output = Vec2;
fn div(self, scalar: T) -> Vec2 {
let scalar = scalar.to_i32().unwrap();
Vec2 {
x: self.x / scalar,
y: self.y / scalar,
}
}
}
impl Neg for Vec2 {
type Output = Vec2;
fn neg(self) -> Vec2 {
Vec2 {
x: -self.x,
y: -self.y,
}
}
}
impl AddAssign for Vec2 {
fn add_assign(&mut self, other: Vec2) {
*self = *self + other
}
}
impl SubAssign for Vec2 {
fn sub_assign(&mut self, other: Vec2) {
*self = *self - other
}
}
impl MulAssign for Vec2 {
fn mul_assign(&mut self, other: Vec2) {
*self = *self * other
}
}
impl DivAssign for Vec2 {
fn div_assign(&mut self, other: Vec2) {
*self = *self / other
}
}
impl<T: ToPrimitive> MulAssign<T> for Vec2 {
fn mul_assign(&mut self, scalar: T) {
*self = *self * scalar
}
}
impl<T: ToPrimitive> DivAssign<T> for Vec2 {
fn div_assign(&mut self, scalar: T) {
*self = *self / scalar
}
}
impl<T> Index<Vec2> for Vec<Vec<T>> {
type Output = T;
/// Allows indexing by a [`Vec2`] for an arbitrary nested Vec.
///
/// ```rust
/// # use ruscii::spatial::Vec2;
/// let vec = vec![vec![1, 2], vec![3, 4], vec![5, 6]];
/// let point = Vec2::xy(1, 1);
/// assert_eq!(vec[point], 4)
/// ```
fn index(&self, index: Vec2) -> &Self::Output {
&self[index.x as usize][index.y as usize]
}
}
impl<T> IndexMut<Vec2> for Vec<Vec<T>> {
fn index_mut(&mut self, index: Vec2) -> &mut Self::Output {
&mut self[index.x as usize][index.y as usize]
}
}
impl From<Direction> for Vec2 {
/// Converts a [`Direction`] to a unit-length [`Vec2`] in that direction.
///
/// Because terminal coordinates begin at the top line, vertical directions are inverted
/// compared to what you may expect. More information in the example. For [`Direction::None`], a
/// zero [`Vec2`] is returned.
///
/// ## Example
///
/// In the terminal, `y` increases going downward from the top. Therefore, [`Direction::Up`]
/// is a negative vector and [`Direction::Down`] is a positive vector.
///
/// ```rust
/// # use ruscii::spatial::{Direction, Vec2};
/// #
/// let up = Vec2::from(Direction::Up);
/// let down = Vec2::from(Direction::Down);
///
/// assert_eq!(up, Vec2::y(-1));
/// assert_eq!(down, Vec2::y(1));
/// ```
fn from(value: Direction) -> Self {
match value {
Direction::Up => Vec2::y(-1),
Direction::Down => Vec2::y(1),
Direction::Right => Vec2::x(1),
Direction::Left => Vec2::x(-1),
Direction::None => Vec2::zero(),
}
}
}
/// The relative directions in a two-dimensional coordinate system, including up, down, left,
/// right, and none.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Direction {
Up,
Down,
Right,
Left,
None,
}
impl Direction {
/// Returns the opposite [`Direction`].
///
/// For [`Direction::None`], [`Direction::None`] is returned.
pub fn opposite(&self) -> Direction {
match *self {
Direction::Up => Direction::Down,
Direction::Down => Direction::Up,
Direction::Right => Direction::Left,
Direction::Left => Direction::Right,
Direction::None => Direction::None,
}
}
}
impl TryFrom<Vec2> for Direction {
type Error = TryFromVec2Error;
/// Converts a [`Vec2`] to a [`Direction`].
///
/// Because terminal coordinates begin at the top line, vertical directions are inverted
/// compared to what you may expect. For more information, see the example.
///
/// ## Errors
///
/// If the given `value` is not orthogonal, i.e., one of the components is not zero,
/// [`TryFromVec2Error`] is returned.
///
/// ## Examples
///
/// In the terminal, `y` increases going downward from the top. Therefore, [`Direction::Up`]
/// is a negative vector and [`Direction::Down`] is a positive vector.
///
/// ```rust
/// # use std::convert::TryFrom;
/// # use ruscii::spatial::{Direction, Vec2};
/// #
/// let negative_y = Direction::try_from(Vec2::y(-1)).unwrap();
/// let positive_y = Direction::try_from(Vec2::y(1)).unwrap();
///
/// assert_eq!(negative_y, Direction::Up);
/// assert_eq!(positive_y, Direction::Down);
/// ```
///
/// Passing non-orthogonal vectors, that is, vectors that are neither parallel to the `x`- or
/// `y`-axis will result in an error.
///
/// ```rust,should_panic
/// # use std::convert::TryFrom;
/// # use ruscii::spatial::{Direction, Vec2};
/// #
/// Direction::try_from(Vec2::xy(1, 1)).unwrap(); // panics!
/// ```
fn try_from(value: Vec2) -> Result<Self, Self::Error> {
match (value.x.cmp(&0), value.y.cmp(&0)) {
(Ordering::Less, Ordering::Equal) => Ok(Direction::Left),
(Ordering::Greater, Ordering::Equal) => Ok(Direction::Right),
(Ordering::Equal, Ordering::Greater) => Ok(Direction::Down),
(Ordering::Equal, Ordering::Less) => Ok(Direction::Up),
(Ordering::Equal, Ordering::Equal) => Ok(Direction::None),
_ => Err(TryFromVec2Error { value }),
}
}
}
#[derive(Debug)]
pub struct TryFromVec2Error {
value: Vec2,
}
impl fmt::Display for TryFromVec2Error {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
write!(
f,
"displacement vector ({}, {}) is not orthogonal",
self.value.x, self.value.y
)
}
}
impl Error for TryFromVec2Error {}