Fix FloatOrd hash being different for different NaN values (bevyengin…

…e#618)

* Fix FloatOrd hash being different for different NaN values

* Fix FloatOrd hashing +0.0 and -0.0 to different values

crates/bevy_core/src/float_ord.rs

@@ -40,7 +40,15 @@ impl Eq for FloatOrd {}
 
 impl Hash for FloatOrd {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        state.write(self.0.as_bytes());
+        if self.0.is_nan() {
+            // Ensure all NaN representations hash to the same value
+            state.write(f32::NAN.as_bytes())
+        } else if self.0 == 0.0 {
+            // Ensure both zeroes hash to the same value
+            state.write(0.0f32.as_bytes())
+        } else {
+            state.write(self.0.as_bytes());
+        }
     }
 }