Add libm feature to bevy_math#11238
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mockersf merged 1 commit intobevyengine:mainfrom Jan 6, 2024
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alice-i-cecile
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Great PR description: this is exactly the sort of context that I wish more contributors gave. |
100-TomatoJuice
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# Objective gltf-rs does its own computations when accessing `transform.matrix()` which does not use glam types, rendering #11238 useless if people were to load gltf models and expecting the results to be deterministic across platforms. ## Solution Move the computation to bevy side which uses glam types, it was already used in one place, so I created one common function to handle the two cases. The added benefit this has, is that some gltf files can have translation, rotation and scale directly instead of matrix which skips the transform computation completely, win-win.
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Objective
Different platforms use their own implementations of several mathematical functions (especially transcendental functions like sin, cos, tan, atan, and so on) to provide hardware-level optimization using intrinsics. This is good for performance, but bad when you expect consistent outputs across machines.
libmis a widely used crate that provides mathematical functions that don't use intrinsics likestdfunctions. This allows bit-for-bit deterministic math across hardware, which is crucial for things like cross-platform deterministic physics simulation.Glam has the
libmfeature for usinglibmfor the math in its own types. This would be nice to expose as a feature inbevy_math.Solution
Add
libmfeature tobevy_math. We could name it something likeenhanced-determinism, but this wouldn't be accurate for the rest of Bevy, so I think justlibmis more fitting and explicit.