Impl TryFrom vector for directions and add InvalidDirectionError

crates/bevy_math/src/primitives/dim2.rs

@@ -1,4 +1,4 @@
-use super::{Primitive2d, WindingOrder};
+use super::{InvalidDirectionError, Primitive2d, WindingOrder};
 use crate::Vec2;
 
 /// A normalized vector pointing in a direction in 2D space
@@ -20,6 +20,14 @@ impl Direction2d {
     }
 }
 
+impl TryFrom<Vec2> for Direction2d {
+    type Error = InvalidDirectionError;
+
+    fn try_from(value: Vec2) -> Result<Self, Self::Error> {
+        Self::new(value).map_or(Err(InvalidDirectionError), Ok)
+    }
+}
+
 impl std::ops::Deref for Direction2d {
     type Target = Vec2;
     fn deref(&self) -> &Self::Target {

crates/bevy_math/src/primitives/dim3.rs

@@ -1,4 +1,4 @@
-use super::Primitive3d;
+use super::{InvalidDirectionError, Primitive3d};
 use crate::Vec3;
 
 /// A normalized vector pointing in a direction in 3D space
@@ -20,6 +20,14 @@ impl Direction3d {
     }
 }
 
+impl TryFrom<Vec3> for Direction3d {
+    type Error = InvalidDirectionError;
+
+    fn try_from(value: Vec3) -> Result<Self, Self::Error> {
+        Self::new(value).map_or(Err(InvalidDirectionError), Ok)
+    }
+}
+
 impl std::ops::Deref for Direction3d {
     type Target = Vec3;
     fn deref(&self) -> &Self::Target {

crates/bevy_math/src/primitives/mod.rs

@@ -13,6 +13,19 @@ pub trait Primitive2d {}
 /// A marker trait for 3D primitives
 pub trait Primitive3d {}
 
+/// An error indicating that a direction is invalid because it is zero or not finite.
+#[derive(Debug)]
+pub struct InvalidDirectionError;
+
+impl std::fmt::Display for InvalidDirectionError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "Direction can not be zero (or very close to zero), or non-finite."
+        )
+    }
+}
+
 /// The winding order for a set of points
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum WindingOrder {