# Smooth and Interpolation Evaluate interpolation and damping immediately without scheduling an action. [Feature status and language/platform compatibility](https://rustic-game-engine.pages.dev/markdown/reference/compatibility.md) Choose an API to see its signature, parameters, examples and behavior. ## APIs - [Smooth.lerp()](https://rustic-game-engine.pages.dev/markdown/api/smooth/lerp.md) - [Smooth.slerp()](https://rustic-game-engine.pages.dev/markdown/api/smooth/slerp.md) - [Smooth.inverseLerp()](https://rustic-game-engine.pages.dev/markdown/api/smooth/inverse-lerp.md) - [Smooth.remap()](https://rustic-game-engine.pages.dev/markdown/api/smooth/remap.md) - [Smooth.smoothDamp()](https://rustic-game-engine.pages.dev/markdown/api/smooth/smooth-damp.md) ## Module guide ## Setup and language support These engine-owned services work in Lua 5.4, Luau, JavaScript, Python, C, C++, C#, Java, PHP, and HTML inline JavaScript. Follow [Use gameplay actions](https://rustic-game-engine.pages.dev/markdown/guides/gameplay-actions.md) to create and attach a script, install external toolchains, and choose the correct language binding. PHP and HTML scripts belong under `ui/`; CSS alone runs no gameplay code. The Calls section uses JavaScript signatures. The function examples below include native syntax for all ten script types, including SDK-specific alternatives and limitations. Attach a JavaScript Object Component script to the specified target and press **Play**. Globals are supplied by the engine. Schedule actions from `Start` or a callback, rather than at script top level. Native languages use typed options and their own builder conventions; see the guide's language bindings. ## Parameters Lerp accepts scalars or three-component vectors. Slerp accepts nonzero [x, y, z, w] quaternions. Progress and inputs must be finite. Easing defaults to Linear. SmoothDamp takes scalar state, a smoothing time and elapsed seconds; feed the returned velocity into the next call. ## Return and timing Math results are synchronous. JavaScript smoothDamp returns {value, velocity}; native return shapes differ (for example C# tuple and Java double[2]). Interpolation aliases Smooth in Lua, Luau, JavaScript, Python, C, C++, PHP and HTML inline JavaScript. C# and Java expose these functions through Smooth. ## Behavior and limitations - This example prints interpolated values immediately in Start; it creates no operation handle. - InverseLerp and remap do not clamp out-of-range values. A degenerate input interval returns inverse progress zero (and remap returns outMin). Damping uses an analytic spring rather than a fixed per-frame fraction. - Use Tween.value or Animation.value when you want the engine to advance interpolation and dispatch callbacks over time. - Check script attachment, enabled state and the Console when an operation fails. Asynchronous errors also appear in operation state. Callback exceptions disable the owner and clean up its actions. - Owner destruction, disable, successful reload or Stop cleans up owned actions and subscriptions. Failed reload retains the previous behavior's operations. See [Operation handles](https://rustic-game-engine.pages.dev/markdown/api/operation-handles.md) for controls and lifetime details.