subtick

Subtick is a term used in time-stepped simulations and game engines to describe a subdivision of a tick, which is a fixed time interval used to advance the simulation. By breaking a tick into smaller increments, subticks allow updates to occur with higher internal resolution without changing the overall tick rate.

In practice, a main loop advances time in discrete ticks. Within each tick, the system performs one or more subtick updates. The state of the world is advanced by small, consistent steps during each subtick, and the results are then used for rendering or for the next tick. This approach helps reduce numerical errors in physics and other time-sensitive systems and can improve the accuracy of collision detection, integration of motion, and event handling.

Common patterns involve choosing a tick duration and a number of subticks per tick. The duration of each subtick is the tick duration divided by the number of subticks. For example, with a 16.67 ms tick and 4 subticks per tick, each subtick would represent about 4.17 ms. Engines may vary in how many subticks they use or whether the number is fixed or adaptive, balancing accuracy and performance.

Subtick concepts are closely related to substeps, fixed-time-step loops, and interpolation. They are often implemented to maintain determinism in physics simulations while keeping rendering smooth. Different frameworks may use slightly different terminology, but the underlying idea remains the same: subdivide time within a tick to improve precision.