Merge #718

718: Vectors: Default, missing Vector2 constants, documentation r=toasteater a=Bromeon

Completes a part of the recent `Vector2`/`Vector3` refactoring:
* `impl Default` (zero vector) for both
* associated constants for `Vector2`
* documentation of constants

Let me know if there's other obvious things that could fit.

Co-authored-by: Jan Haller <bromeon@gmail.com>

Author: bors[bot]

gdnative-core/src/core_types/vector2.rs

@@ -2,7 +2,7 @@ use super::IsEqualApprox;
 use glam::Vec2;
 use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};
 
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, Default)]
 #[repr(C)]
 pub struct Vector2 {
     pub x: f32,
@@ -13,6 +13,27 @@ pub struct Vector2 {
 ///
 /// See the official [`Godot documentation`](https://docs.godotengine.org/en/3.1/classes/class_vector2.html).
 impl Vector2 {
+    /// The zero vector.
+    pub const ZERO: Vector2 = Vector2::new(0.0, 0.0);
+
+    /// A vector with all components set to 1. Typically used for scaling.
+    pub const ONE: Vector2 = Vector2::new(1.0, 1.0);
+
+    /// A vector with all components set to +infinity.
+    pub const INF: Vector2 = Vector2::new(f32::INFINITY, f32::INFINITY);
+
+    /// Unit vector in -X direction.
+    pub const LEFT: Vector2 = Vector2::new(-1.0, 0.0);
+
+    /// Unit vector in +X direction.
+    pub const RIGHT: Vector2 = Vector2::new(1.0, 0.0);
+
+    /// Unit vector in -Y direction (the Y axis points down in 2D).
+    pub const UP: Vector2 = Vector2::new(0.0, -1.0);
+
+    /// Unit vector in +Y direction (the Y axis points down in 2D).
+    pub const DOWN: Vector2 = Vector2::new(0.0, 1.0);
+
     /// Constructs a new Vector2 from the given x and y.
     #[inline]
     pub const fn new(x: f32, y: f32) -> Self {
@@ -455,7 +476,7 @@ mod tests {
                 V::new(-1.2, 0.8),
                 V::new(1.2, 10.3),
                 V::new(-5.4, 4.2),
-                0.2
+                0.2,
             ))
         );
 
@@ -464,7 +485,7 @@ mod tests {
                 V::new(-3.7, 2.1),
                 V::new(5.4, -8.5),
                 V::new(-10.8, -6.6),
-                0.6
+                0.6,
             ))
         );
     }

gdnative-core/src/core_types/vector3.rs

@@ -3,7 +3,7 @@ use super::IsEqualApprox;
 use glam::Vec3A;
 use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};
 
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, Default)]
 #[repr(C)]
 pub struct Vector3 {
     pub x: f32,
@@ -23,14 +23,31 @@ pub enum Axis {
 ///
 /// See the official [`Godot documentation`](https://docs.godotengine.org/en/3.1/classes/class_vector3.html).
 impl Vector3 {
+    /// The zero vector.
     pub const ZERO: Self = Self::new(0.0, 0.0, 0.0);
+
+    /// A vector with all components set to 1. Typically used for scaling.
     pub const ONE: Self = Self::new(1.0, 1.0, 1.0);
+
+    /// A vector with all components set to +infinity.
     pub const INF: Self = Self::new(f32::INFINITY, f32::INFINITY, f32::INFINITY);
+
+    /// Unit vector in -X direction.
     pub const LEFT: Self = Self::new(-1.0, 0.0, 0.0);
+
+    /// Unit vector in +X direction.
     pub const RIGHT: Self = Self::new(1.0, 0.0, 0.0);
+
+    /// Unit vector in +Y direction.
     pub const UP: Self = Self::new(0.0, 1.0, 0.0);
+
+    /// Unit vector in -Y direction.
     pub const DOWN: Self = Self::new(0.0, -1.0, 0.0);
+
+    /// Unit vector in -Z direction.
     pub const FORWARD: Self = Self::new(0.0, 0.0, -1.0);
+
+    /// Unit vector in +Z direction.
     pub const BACK: Self = Self::new(0.0, 0.0, 1.0);
 
     /// Returns a Vector3 with the given components.