timespeed

Timespeed refers to a multiplier that scales the rate at which simulated time advances relative to real-world time. It is a concept used in computer simulations, video games, and digital animations rather than a fundamental physical quantity. When timespeed equals 1.0, one real second corresponds to one simulation second; values greater than 1.0 accelerate the passage of simulated time, while values between 0 and 1.0 slow it down or pause it at 0.

In practice, engines implement timespeed by multiplying the real-time delta (dt) by the timespeed factor to compute the effective step used for updates to physics, animation, and AI. This approach preserves frame-rate independence and allows the simulation to progress at variable rates without changing the underlying code that consumes time. Users can typically adjust timespeed on the fly to fast-forward, slow-motion, or pause the simulation for debugging or pacing.

Timespeed is a software construct rather than a physical law. It is used to control the rate of simulation time and is independent of display frame rate. In some engines, changing timespeed requires re-synchronizing subsystems (graphics, physics, networking) to preserve determinism and stability. For networked simulations, a fixed timespeed across clients is often important to maintain consistent world states.

Implementation considerations include choosing a stable update strategy, handling changes in timespeed smoothly, and preventing instability when stepping through large time increments. Techniques such as fixed timesteps with substepping, interpolation, and clamping help maintain accuracy and determinism. Limitations include reduced precision at very high speeds, potential desynchronization in multiplayer contexts, and the need for thorough testing when timespeed changes.