Add no_std Support to bevy_math (#15810)

# Objective - Contributes to #15460 ## Solution - Added two new features, `std` (default) and `alloc`, gating `std` and `alloc` behind them respectively. - Added missing `f32` functions to `std_ops` as required. These `f32` methods have been added to the `clippy.toml` deny list to aid in `no_std` development. ## Testing - CI - `cargo clippy -p bevy_math --no-default-features --features libm --target "x86_64-unknown-none"` - `cargo test -p bevy_math --no-default-features --features libm` - `cargo test -p bevy_math --no-default-features --features "libm, alloc"` - `cargo test -p bevy_math --no-default-features --features "libm, alloc, std"` - `cargo test -p bevy_math --no-default-features --features "std"` ## Notes The following items require the `alloc` feature to be enabled: - `CubicBSpline` - `CubicBezier` - `CubicCardinalSpline` - `CubicCurve` - `CubicGenerator` - `CubicHermite` - `CubicNurbs` - `CyclicCubicGenerator` - `RationalCurve` - `RationalGenerator` - `BoxedPolygon` - `BoxedPolyline2d` - `BoxedPolyline3d` - `SampleCurve` - `SampleAutoCurve` - `UnevenSampleCurve` - `UnevenSampleAutoCurve` - `EvenCore` - `UnevenCore` - `ChunkedUnevenCore` This requirement could be relaxed in certain cases, but I had erred on the side of gating rather than modifying. Since `no_std` is a new set of platforms we are adding support to, and the `alloc` feature is enabled by default, this is not a breaking change. --------- Co-authored-by: Benjamin Brienen <[email protected]> Co-authored-by: Matty <[email protected]> Co-authored-by: Joona Aalto <[email protected]>
bevyengine · Dec 3, 2024 · a8b9c94 · a8b9c94
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diff --git a/crates/bevy_math/Cargo.toml b/crates/bevy_math/Cargo.toml
@@ -10,20 +10,20 @@ keywords = ["bevy"]
 rust-version = "1.81.0"
 
 [dependencies]
-glam = { version = "0.29", features = ["bytemuck"] }
+glam = { version = "0.29", default-features = false, features = ["bytemuck"] }
 derive_more = { version = "1", default-features = false, features = [
   "error",
   "from",
   "display",
   "into",
 ] }
-itertools = "0.13.0"
-serde = { version = "1", features = ["derive"], optional = true }
+itertools = { version = "0.13.0", default-features = false }
+serde = { version = "1", default-features = false, features = [
+  "derive",
+], optional = true }
 libm = { version = "0.2", optional = true }
-approx = { version = "0.5", optional = true }
-rand = { version = "0.8", features = [
-  "alloc",
-], default-features = false, optional = true }
+approx = { version = "0.5", default-features = false, optional = true }
+rand = { version = "0.8", default-features = false, optional = true }
 rand_distr = { version = "0.4.3", optional = true }
 smallvec = { version = "1.11" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.15.0-dev", features = [
@@ -36,11 +36,30 @@ approx = "0.5"
 rand = "0.8"
 rand_chacha = "0.3"
 # Enable the approx feature when testing.
-bevy_math = { path = ".", version = "0.15.0-dev", features = ["approx"] }
-glam = { version = "0.29", features = ["approx"] }
+bevy_math = { path = ".", version = "0.15.0-dev", default-features = false, features = [
+  "approx",
+] }
+glam = { version = "0.29", default-features = false, features = ["approx"] }
 
 [features]
-default = ["rand", "bevy_reflect", "curve"]
+default = ["std", "rand", "bevy_reflect", "curve"]
+std = [
+  "alloc",
+  "glam/std",
+  "derive_more/std",
+  "itertools/use_std",
+  "serde?/std",
+  "approx?/std",
+  "rand?/std",
+  "rand_distr?/std",
+]
+alloc = [
+  "itertools/use_alloc",
+  "serde?/alloc",
+  "rand?/alloc",
+  "rand_distr?/alloc",
+]
+
 serialize = ["dep:serde", "glam/serde"]
 # Enable approx for glam types to approximate floating point equality comparisons and assertions
 approx = ["dep:approx", "glam/approx"]
@@ -57,6 +76,8 @@ debug_glam_assert = ["glam/debug-glam-assert"]
 rand = ["dep:rand", "dep:rand_distr", "glam/rand"]
 # Include code related to the Curve trait
 curve = []
+# Enable bevy_reflect (requires std)
+bevy_reflect = ["dep:bevy_reflect", "std"]
 
 [lints]
 workspace = true

diff --git a/crates/bevy_math/clippy.toml b/crates/bevy_math/clippy.toml
@@ -26,4 +26,13 @@ disallowed-methods = [
   { path = "f32::asinh", reason = "use ops::asinh instead for libm determinism" },
   { path = "f32::acosh", reason = "use ops::acosh instead for libm determinism" },
   { path = "f32::atanh", reason = "use ops::atanh instead for libm determinism" },
+  # These methods have defined precision, but are only available from the standard library,
+  # not in core. Using these substitutes allows for no_std compatibility.
+  { path = "f32::rem_euclid", reason = "use ops::rem_euclid instead for no_std compatibility" },
+  { path = "f32::abs", reason = "use ops::abs instead for no_std compatibility" },
+  { path = "f32::sqrt", reason = "use ops::sqrt instead for no_std compatibility" },
+  { path = "f32::copysign", reason = "use ops::copysign instead for no_std compatibility" },
+  { path = "f32::round", reason = "use ops::round instead for no_std compatibility" },
+  { path = "f32::floor", reason = "use ops::floor instead for no_std compatibility" },
+  { path = "f32::fract", reason = "use ops::fract instead for no_std compatibility" },
 ]
diff --git a/crates/bevy_math/src/bounding/bounded2d/mod.rs b/crates/bevy_math/src/bounding/bounded2d/mod.rs
@@ -2,6 +2,7 @@ mod primitive_impls;
 
 use super::{BoundingVolume, IntersectsVolume};
 use crate::{
+    ops,
     prelude::{Mat2, Rot2, Vec2},
     FloatPow, Isometry2d,
 };
@@ -296,12 +297,12 @@ mod aabb2d_tests {
             min: Vec2::new(-1., -1.),
             max: Vec2::new(1., 1.),
         };
-        assert!((aabb.visible_area() - 4.).abs() < f32::EPSILON);
+        assert!(ops::abs(aabb.visible_area() - 4.) < f32::EPSILON);
         let aabb = Aabb2d {
             min: Vec2::new(0., 0.),
             max: Vec2::new(1., 0.5),
         };
-        assert!((aabb.visible_area() - 0.5).abs() < f32::EPSILON);
+        assert!(ops::abs(aabb.visible_area() - 0.5) < f32::EPSILON);
     }
 
     #[test]
@@ -488,7 +489,7 @@ impl BoundingCircle {
             }
         }
 
-        BoundingCircle::new(isometry * center, radius_squared.sqrt())
+        BoundingCircle::new(isometry * center, ops::sqrt(radius_squared))
     }
 
     /// Get the radius of the bounding circle
@@ -539,7 +540,7 @@ impl BoundingVolume for BoundingCircle {
     #[inline(always)]
     fn contains(&self, other: &Self) -> bool {
         let diff = self.radius() - other.radius();
-        self.center.distance_squared(other.center) <= diff.squared().copysign(diff)
+        self.center.distance_squared(other.center) <= ops::copysign(diff.squared(), diff)
     }
 
     #[inline(always)]
@@ -614,14 +615,14 @@ mod bounding_circle_tests {
     use super::BoundingCircle;
     use crate::{
         bounding::{BoundingVolume, IntersectsVolume},
-        Vec2,
+        ops, Vec2,
     };
 
     #[test]
     fn area() {
         let circle = BoundingCircle::new(Vec2::ONE, 5.);
         // Since this number is messy we check it with a higher threshold
-        assert!((circle.visible_area() - 78.5398).abs() < 0.001);
+        assert!(ops::abs(circle.visible_area() - 78.5398) < 0.001);
     }
 
     #[test]
@@ -647,7 +648,7 @@ mod bounding_circle_tests {
         let b = BoundingCircle::new(Vec2::new(1., -4.), 1.);
         let merged = a.merge(&b);
         assert!((merged.center - Vec2::new(1., 0.5)).length() < f32::EPSILON);
-        assert!((merged.radius() - 5.5).abs() < f32::EPSILON);
+        assert!(ops::abs(merged.radius() - 5.5) < f32::EPSILON);
         assert!(merged.contains(&a));
         assert!(merged.contains(&b));
         assert!(!a.contains(&merged));
@@ -679,7 +680,7 @@ mod bounding_circle_tests {
     fn grow() {
         let a = BoundingCircle::new(Vec2::ONE, 5.);
         let padded = a.grow(1.25);
-        assert!((padded.radius() - 6.25).abs() < f32::EPSILON);
+        assert!(ops::abs(padded.radius() - 6.25) < f32::EPSILON);
         assert!(padded.contains(&a));
         assert!(!a.contains(&padded));
     }
@@ -688,7 +689,7 @@ mod bounding_circle_tests {
     fn shrink() {
         let a = BoundingCircle::new(Vec2::ONE, 5.);
         let shrunk = a.shrink(0.5);
-        assert!((shrunk.radius() - 4.5).abs() < f32::EPSILON);
+        assert!(ops::abs(shrunk.radius() - 4.5) < f32::EPSILON);
         assert!(a.contains(&shrunk));
         assert!(!shrunk.contains(&a));
     }
@@ -697,7 +698,7 @@ mod bounding_circle_tests {
     fn scale_around_center() {
         let a = BoundingCircle::new(Vec2::ONE, 5.);
         let scaled = a.scale_around_center(2.);
-        assert!((scaled.radius() - 10.).abs() < f32::EPSILON);
+        assert!(ops::abs(scaled.radius() - 10.) < f32::EPSILON);
         assert!(!a.contains(&scaled));
         assert!(scaled.contains(&a));
     }

diff --git a/crates/bevy_math/src/bounding/bounded2d/primitive_impls.rs b/crates/bevy_math/src/bounding/bounded2d/primitive_impls.rs
@@ -3,14 +3,16 @@
 use crate::{
     ops,
     primitives::{
-        Annulus, Arc2d, BoxedPolygon, BoxedPolyline2d, Capsule2d, Circle, CircularSector,
-        CircularSegment, Ellipse, Line2d, Plane2d, Polygon, Polyline2d, Rectangle, RegularPolygon,
-        Rhombus, Segment2d, Triangle2d,
+        Annulus, Arc2d, Capsule2d, Circle, CircularSector, CircularSegment, Ellipse, Line2d,
+        Plane2d, Polygon, Polyline2d, Rectangle, RegularPolygon, Rhombus, Segment2d, Triangle2d,
     },
     Dir2, Isometry2d, Mat2, Rot2, Vec2,
 };
 use core::f32::consts::{FRAC_PI_2, PI, TAU};
 
+#[cfg(feature = "alloc")]
+use crate::primitives::{BoxedPolygon, BoxedPolyline2d};
+
 use smallvec::SmallVec;
 
 use super::{Aabb2d, Bounded2d, BoundingCircle};
@@ -41,11 +43,11 @@ fn arc_bounding_points(arc: Arc2d, rotation: impl Into<Rot2>) -> SmallVec<[Vec2;
     // The half-angles are measured from a starting point of π/2, being the angle of Vec2::Y.
     // Compute the normalized angles of the endpoints with the rotation taken into account, and then
     // check if we are looking for an angle that is between or outside them.
-    let left_angle = (FRAC_PI_2 + arc.half_angle + rotation.as_radians()).rem_euclid(TAU);
-    let right_angle = (FRAC_PI_2 - arc.half_angle + rotation.as_radians()).rem_euclid(TAU);
+    let left_angle = ops::rem_euclid(FRAC_PI_2 + arc.half_angle + rotation.as_radians(), TAU);
+    let right_angle = ops::rem_euclid(FRAC_PI_2 - arc.half_angle + rotation.as_radians(), TAU);
     let inverted = left_angle < right_angle;
     for extremum in [Vec2::X, Vec2::Y, Vec2::NEG_X, Vec2::NEG_Y] {
-        let angle = extremum.to_angle().rem_euclid(TAU);
+        let angle = ops::rem_euclid(extremum.to_angle(), TAU);
         // If inverted = true, then right_angle > left_angle, so we are looking for an angle that is not between them.
         // There's a chance that this condition fails due to rounding error, if the endpoint angle is juuuust shy of the axis.
         // But in that case, the endpoint itself is within rounding error of the axis and will define the bounds just fine.
@@ -286,6 +288,7 @@ impl<const N: usize> Bounded2d for Polyline2d<N> {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl Bounded2d for BoxedPolyline2d {
     fn aabb_2d(&self, isometry: impl Into<Isometry2d>) -> Aabb2d {
         Aabb2d::from_point_cloud(isometry, &self.vertices)
@@ -348,7 +351,8 @@ impl Bounded2d for Rectangle {
         // Compute the AABB of the rotated rectangle by transforming the half-extents
         // by an absolute rotation matrix.
         let (sin, cos) = isometry.rotation.sin_cos();
-        let abs_rot_mat = Mat2::from_cols_array(&[cos.abs(), sin.abs(), sin.abs(), cos.abs()]);
+        let abs_rot_mat =
+            Mat2::from_cols_array(&[ops::abs(cos), ops::abs(sin), ops::abs(sin), ops::abs(cos)]);
         let half_size = abs_rot_mat * self.half_size;
 
         Aabb2d::new(isometry.translation, half_size)
@@ -371,6 +375,7 @@ impl<const N: usize> Bounded2d for Polygon<N> {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl Bounded2d for BoxedPolygon {
     fn aabb_2d(&self, isometry: impl Into<Isometry2d>) -> Aabb2d {
         Aabb2d::from_point_cloud(isometry, &self.vertices)
@@ -470,6 +475,7 @@ mod tests {
     // Arcs and circular segments have the same bounding shapes so they share test cases.
     fn arc_and_segment() {
         struct TestCase {
+            #[allow(unused)]
             name: &'static str,
             arc: Arc2d,
             translation: Vec2,
@@ -487,7 +493,7 @@ mod tests {
         }
 
         // The apothem of an arc covering 1/6th of a circle.
-        let apothem = f32::sqrt(3.0) / 2.0;
+        let apothem = ops::sqrt(3.0) / 2.0;
         let tests = [
             // Test case: a basic minor arc
             TestCase {
@@ -558,7 +564,7 @@ mod tests {
                 aabb_min: Vec2::ZERO,
                 aabb_max: Vec2::splat(1.0),
                 bounding_circle_center: Vec2::splat(0.5),
-                bounding_circle_radius: f32::sqrt(2.0) / 2.0,
+                bounding_circle_radius: ops::sqrt(2.0) / 2.0,
             },
             // Test case: a basic major arc
             TestCase {
@@ -597,6 +603,7 @@ mod tests {
         ];
 
         for test in tests {
+            #[cfg(feature = "std")]
             println!("subtest case: {}", test.name);
             let segment: CircularSegment = test.arc.into();
 
@@ -622,6 +629,7 @@ mod tests {
     #[test]
     fn circular_sector() {
         struct TestCase {
+            #[allow(unused)]
             name: &'static str,
             arc: Arc2d,
             translation: Vec2,
@@ -639,8 +647,8 @@ mod tests {
         }
 
         // The apothem of an arc covering 1/6th of a circle.
-        let apothem = f32::sqrt(3.0) / 2.0;
-        let inv_sqrt_3 = f32::sqrt(3.0).recip();
+        let apothem = ops::sqrt(3.0) / 2.0;
+        let inv_sqrt_3 = ops::sqrt(3.0).recip();
         let tests = [
             // Test case: An sector whose arc is minor, but whose bounding circle is not the circumcircle of the endpoints and center
             TestCase {
@@ -717,7 +725,7 @@ mod tests {
                 aabb_min: Vec2::ZERO,
                 aabb_max: Vec2::splat(1.0),
                 bounding_circle_center: Vec2::splat(0.5),
-                bounding_circle_radius: f32::sqrt(2.0) / 2.0,
+                bounding_circle_radius: ops::sqrt(2.0) / 2.0,
             },
             TestCase {
                 name: "5/6th circle untransformed",
@@ -753,6 +761,7 @@ mod tests {
         ];
 
         for test in tests {
+            #[cfg(feature = "std")]
             println!("subtest case: {}", test.name);
             let sector: CircularSector = test.arc.into();
 

diff --git a/crates/bevy_math/src/bounding/bounded3d/extrusion.rs b/crates/bevy_math/src/bounding/bounded3d/extrusion.rs
@@ -6,12 +6,15 @@ use crate::{
     bounding::{BoundingCircle, BoundingVolume},
     ops,
     primitives::{
-        BoxedPolygon, BoxedPolyline2d, Capsule2d, Cuboid, Cylinder, Ellipse, Extrusion, Line2d,
-        Polygon, Polyline2d, Primitive2d, Rectangle, RegularPolygon, Segment2d, Triangle2d,
+        Capsule2d, Cuboid, Cylinder, Ellipse, Extrusion, Line2d, Polygon, Polyline2d, Primitive2d,
+        Rectangle, RegularPolygon, Segment2d, Triangle2d,
     },
     Isometry2d, Isometry3d, Quat, Rot2,
 };
 
+#[cfg(feature = "alloc")]
+use crate::primitives::{BoxedPolygon, BoxedPolyline2d};
+
 use crate::{bounding::Bounded2d, primitives::Circle};
 
 use super::{Aabb3d, Bounded3d, BoundingSphere};
@@ -26,7 +29,7 @@ impl BoundedExtrusion for Circle {
         let top = (segment_dir * half_depth).abs();
 
         let e = (Vec3A::ONE - segment_dir * segment_dir).max(Vec3A::ZERO);
-        let half_size = self.radius * Vec3A::new(e.x.sqrt(), e.y.sqrt(), e.z.sqrt());
+        let half_size = self.radius * Vec3A::new(ops::sqrt(e.x), ops::sqrt(e.y), ops::sqrt(e.z));
 
         Aabb3d {
             min: isometry.translation - half_size - top,
@@ -56,8 +59,8 @@ impl BoundedExtrusion for Ellipse {
             let m = -axis.x / axis.y;
             let signum = axis.signum();
 
-            let y = signum.y * b * b / (b * b + m * m * a * a).sqrt();
-            let x = signum.x * a * (1. - y * y / b / b).sqrt();
+            let y = signum.y * b * b / ops::sqrt(b * b + m * m * a * a);
+            let x = signum.x * a * ops::sqrt(1. - y * y / b / b);
             isometry.rotation * Vec3A::new(x, y, 0.)
         });
 
@@ -104,6 +107,7 @@ impl<const N: usize> BoundedExtrusion for Polyline2d<N> {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl BoundedExtrusion for BoxedPolyline2d {
     fn extrusion_aabb_3d(&self, half_depth: f32, isometry: impl Into<Isometry3d>) -> Aabb3d {
         let isometry = isometry.into();
@@ -144,6 +148,7 @@ impl<const N: usize> BoundedExtrusion for Polygon<N> {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl BoundedExtrusion for BoxedPolygon {
     fn extrusion_aabb_3d(&self, half_depth: f32, isometry: impl Into<Isometry3d>) -> Aabb3d {
         let isometry = isometry.into();
@@ -301,7 +306,7 @@ mod tests {
 
         let bounding_sphere = extrusion.bounding_sphere(isometry);
         assert_eq!(bounding_sphere.center, translation.into());
-        assert_eq!(bounding_sphere.radius(), 8f32.sqrt());
+        assert_eq!(bounding_sphere.radius(), ops::sqrt(8f32));
     }
 
     #[test]
@@ -444,7 +449,7 @@ mod tests {
 
         let bounding_sphere = extrusion.bounding_sphere(isometry);
         assert_eq!(bounding_sphere.center, translation.into());
-        assert_eq!(bounding_sphere.radius(), 8f32.sqrt());
+        assert_eq!(bounding_sphere.radius(), ops::sqrt(8f32));
     }
 
     #[test]