Introduce AspectRatio struct (#10368)

# Objective

- Fix an inconsistency in the calculation of aspect ratio's. 
- Fixes #10288 

## Solution

- Created an intermediate `AspectRatio` struct, as suggested in the
issue. This is currently just used in any places where aspect ratio
calculations happen, to prevent doing it wrong. In my and @mamekoro 's
opinion, it would be better if this was used instead of a normal `f32`
in various places, but I didn't want to make too many changes to begin
with.

## Migration Guide
- Anywhere where you are currently expecting a f32 when getting aspect
ratios, you will now receive a `AspectRatio` struct. this still holds
the same value.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>

crates/bevy_core_pipeline/src/bloom/settings.rs

@@ -1,6 +1,6 @@
 use super::downsampling_pipeline::BloomUniforms;
 use bevy_ecs::{prelude::Component, query::QueryItem, reflect::ReflectComponent};
-use bevy_math::{URect, UVec4, Vec4};
+use bevy_math::{AspectRatio, URect, UVec4, Vec4};
 use bevy_reflect::{std_traits::ReflectDefault, Reflect};
 use bevy_render::{extract_component::ExtractComponent, prelude::Camera};
 
@@ -210,7 +210,7 @@ impl ExtractComponent for BloomSettings {
                     viewport: UVec4::new(origin.x, origin.y, size.x, size.y).as_vec4()
                         / UVec4::new(target_size.x, target_size.y, target_size.x, target_size.y)
                             .as_vec4(),
-                    aspect: size.x as f32 / size.y as f32,
+                    aspect: AspectRatio::from_pixels(size.x, size.y).into(),
                 };
 
                 Some((settings.clone(), uniform))

crates/bevy_math/src/aspect_ratio.rs

@@ -0,0 +1,25 @@
+//! Provides a simple aspect ratio struct to help with calculations.
+
+/// An `AspectRatio` is the ratio of width to height.
+pub struct AspectRatio(f32);
+
+impl AspectRatio {
+    /// Create a new `AspectRatio` from a given `width` and `height`.
+    #[inline]
+    pub fn new(width: f32, height: f32) -> Self {
+        Self(width / height)
+    }
+
+    /// Create a new `AspectRatio` from a given amount of `x` pixels and `y` pixels.
+    #[inline]
+    pub fn from_pixels(x: u32, y: u32) -> Self {
+        Self::new(x as f32, y as f32)
+    }
+}
+
+impl From<AspectRatio> for f32 {
+    #[inline]
+    fn from(aspect_ratio: AspectRatio) -> Self {
+        aspect_ratio.0
+    }
+}

crates/bevy_math/src/lib.rs

@@ -7,12 +7,14 @@
 #![warn(missing_docs)]
 
 mod affine3;
+mod aspect_ratio;
 pub mod cubic_splines;
 pub mod primitives;
 mod ray;
 mod rects;
 
 pub use affine3::*;
+pub use aspect_ratio::AspectRatio;
 pub use ray::{Ray2d, Ray3d};
 pub use rects::*;
 

crates/bevy_pbr/src/light.rs

@@ -1,7 +1,9 @@
 use std::collections::HashSet;
 
 use bevy_ecs::prelude::*;
-use bevy_math::{Mat4, UVec2, UVec3, Vec2, Vec3, Vec3A, Vec3Swizzles, Vec4, Vec4Swizzles};
+use bevy_math::{
+    AspectRatio, Mat4, UVec2, UVec3, Vec2, Vec3, Vec3A, Vec3Swizzles, Vec4, Vec4Swizzles,
+};
 use bevy_reflect::prelude::*;
 use bevy_render::{
     camera::{Camera, CameraProjection},
@@ -732,7 +734,8 @@ impl ClusterConfig {
             ClusterConfig::FixedZ {
                 total, z_slices, ..
             } => {
-                let aspect_ratio = screen_size.x as f32 / screen_size.y as f32;
+                let aspect_ratio: f32 =
+                    AspectRatio::from_pixels(screen_size.x, screen_size.y).into();
                 let mut z_slices = *z_slices;
                 if *total < z_slices {
                     warn!("ClusterConfig has more z-slices than total clusters!");

crates/bevy_render/src/camera/projection.rs

@@ -2,7 +2,7 @@ use std::marker::PhantomData;
 
 use bevy_app::{App, Plugin, PostStartup, PostUpdate};
 use bevy_ecs::{prelude::*, reflect::ReflectComponent};
-use bevy_math::{Mat4, Rect, Vec2, Vec3A};
+use bevy_math::{AspectRatio, Mat4, Rect, Vec2, Vec3A};
 use bevy_reflect::{
     std_traits::ReflectDefault, GetTypeRegistration, Reflect, ReflectDeserialize, ReflectSerialize,
 };
@@ -155,7 +155,7 @@ impl CameraProjection for PerspectiveProjection {
     }
 
     fn update(&mut self, width: f32, height: f32) {
-        self.aspect_ratio = width / height;
+        self.aspect_ratio = AspectRatio::new(width, height).into();
     }
 
     fn far(&self) -> f32 {

crates/bevy_render/src/texture/image.rs

@@ -14,7 +14,7 @@ use crate::{
 use bevy_asset::Asset;
 use bevy_derive::{Deref, DerefMut};
 use bevy_ecs::system::{lifetimeless::SRes, Resource, SystemParamItem};
-use bevy_math::{UVec2, Vec2};
+use bevy_math::{AspectRatio, UVec2, Vec2};
 use bevy_reflect::Reflect;
 use serde::{Deserialize, Serialize};
 use std::hash::Hash;
@@ -539,10 +539,10 @@ impl Image {
         self.texture_descriptor.size.height
     }
 
-    /// Returns the aspect ratio (height/width) of a 2D image.
+    /// Returns the aspect ratio (width / height) of a 2D image.
     #[inline]
-    pub fn aspect_ratio(&self) -> f32 {
-        self.height() as f32 / self.width() as f32
+    pub fn aspect_ratio(&self) -> AspectRatio {
+        AspectRatio::from_pixels(self.width(), self.height())
     }
 
     /// Returns the size of a 2D image as f32.