Time Measurement in Game Programming
11 hours ago
- Time measurement is crucial for games and real-time programs, requiring careful selection of data types, units, and zero points to avoid precision and range limitations.
- Integer types (e.g., 64-bit) are preferred for absolute time to avoid precision loss at large values, while floats can be used for small deltas.
- Common time-reading functions include QueryPerformanceCounter (high precision), GetTickCount (low accuracy), and clock_gettime (Unix); each has trade-offs in monotonicity, accuracy, and platform support.
- A dedicated GameTime class (storing cycles from QPC) with overloaded operators ensures correct logical operations (e.g., no adding times) and simplifies time handling.
- Precautions like clamping the time delta and subtracting a start time from absolute measurements prevent catastrophic cancellation and other floating-point issues.
- FPS is a nonlinear measure (reciprocal of frame time) and should not be used for performance comparisons; instead, use frame time in milliseconds for accurate analysis.