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Timewarp is a feature of [[Oculus SDK]]. It was initially released in the version 0.3.1 of the SDK. [[#Positional Timewarp|Positional Timewarp]] was introduced in [[Oculus PC SDK]] 0.6.0<ref>https://twitter.com/volgaksoy/status/599251845156995072</ref>.
[[Runtime]]s for various platforms such as the [[Oculus Runtime]] and [[SteamVR Runtime]] are responsible for Timewarp. Different runtimes [[#Oculus Rift vs. SteamVR vs. PSVR|perform timewarp differently]].
==Asynchronous Timewarp (ATW)==
==Oculus Rift vs. SteamVR vs. PSVR==
The [[Oculus Runtime]] uses asynchronous timewarp to interpolate frames from any frame rate to 90. I.e. the game has a massive explosion, fps drop to 70, async timewarp interpolates to 90.
The [[SteamVR Runtime]] uses reprojection when the target frame rate is not met. But instead of interpolating from an arbitrary frame rate to 90, it forces the game to render at 45fps and then doubles the frame rate via interpolation.
Both approaches have advantages and disadvantages. Asynchronous timewarp is great for very short dips below 90, but it's variability means frame times aren't that smooth. SteamVR's reprojection has very smooth and predictable frame times, however the fps hit is much higher, which could look weird if animations and physics are meant to run with 90Hz.
Sony's [[PSVR]] is using SteamVR style reprojection as one of their default modes. Games can render at 60fps and will be reprojected to 120.
==References==
