rustic.delta_time()
Compatibility
Supported languages: C, C++, C#, Python, JavaScript, Lua 5.4, Luau, Java, PHP and HTML/inline JavaScript (binding spellings and return shapes differ).
Use a compatible native engine build and the language tools required by your binding. This does not establish browser/mobile export or release qualification for every OS.
The signature below is the shared reference notation; language examples show the actual binding syntax. Question marks mark optional arguments and explicit defaults are shown where recorded. Do not copy reference notation as a typed declaration.
See Feature status and compatibility for API 1.0/1.1 and per-method restrictions. Engine release tags and Docs v0.1 are independent versions.
Signature
rustic.delta_time()
Setup and usage
Read the entity ID when another system needs a stable reference to this owner. Use delta_time with Update for frame-rate-independent presentation and fixed_delta_time with FixedUpdate for simulation.
Parameters
This call has no arguments.
Return and timing
The ID is a stable string. Time values are finite seconds.
Execution behavior
Core write timing differs between immediate Lua host calls, deferred JavaScript/Web commands and external SDK query flushes. Scheduled actions advance with the scene clock; synchronous queries evaluate at the call. Follow execution rules and the return/timing notes for this category.
Language examples
Use these snippets inside Start/on_start after generating the Programming Workspace and attaching the script. Python imports rustic, Game and instance from rustic; C++ includes rustic.hpp; C includes rustic.h; C# uses using static Rustic; Java runs inside a Rustic subclass; PHP declares global $rustic, $Game, $instance in its callback. HTML uses an inline script in a ui/ asset. See Lifecycle callbacks for complete registration examples. Public-property examples require a declared integer health property. Scene examples require the named objects to exist before Play.
Lua 5.4
local id = rustic.entity_id()
local dt = rustic.delta_time()
local fixedDt = rustic.fixed_delta_time()JavaScript
const id = rustic.entity_id();
const dt = rustic.delta_time();
const fixedDt = rustic.fixed_delta_time();Python
entity_id = rustic.entity_id()
dt = rustic.delta_time()
fixed_dt = rustic.fixed_delta_time()C++
std::string id = rustic.entity_id();
double dt = rustic.delta_time();
double fixedDt = rustic.fixed_delta_time();C#
string id = rustic.entity_id();
double dt = rustic.delta_time();
double fixedDt = rustic.fixed_delta_time();Luau
local id = rustic.entity_id()
local dt = rustic.delta_time()
local fixedDt = rustic.fixed_delta_time()C
const char *id = rustic.entity_id();
double dt = rustic.delta_time();
double fixedDt = rustic.fixed_delta_time();Java
String id = rustic.entity_id();
double dt = rustic.delta_time();
double fixedDt = rustic.fixed_delta_time();PHP
$id = $rustic->entity_id();
$dt = $rustic->delta_time();
$fixedDt = $rustic->fixed_delta_time();HTML / inline JS
const id = rustic.entity_id();
const dt = rustic.delta_time();
const fixedDt = rustic.fixed_delta_time();Shared Entity & time constraints
- Every gameplay language calls the engine-owned API. Rustic supplies SDKs and dispatches callbacks; scripts do not parse requests or serialize responses. See the language guide for complete setup and callback registration.
Errors and debugging
Read the constraints above and the Console diagnostic. Invalid types, non-finite values, stale targets or unavailable native services can fail validation. A failed callback disables the behavior; a failed source reload keeps the last good instance. Exact error messages depend on the language adapter. See Troubleshooting.