stopwatch.c

Using stopwatch for precise timing and delta time measurements.

Using stopwatch for precise timing and delta time measurements.A stopwatch tracks both total elapsed time and delta time (time since last measurement). This is essential for frame-independent game logic, animation, and performance profiling.

It is a plain console program with its own loop rather than an App (bj_run_app) program: there is no window or event handling to drive, so the bj_sleep() that paces this loop is exactly what such a program should use.

 
#include <banjo/log.h>
#include <banjo/main.h>
#include <banjo/system.h>
#include <banjo/time.h>
 
int main(int argc, char* argv[]) {
    (void)argc; (void)argv;
 
    if (!bj_begin(BJ_NO_SYSTEM, 0)) {
        return 1;
    }
 
    // A stopwatch must be zero-initialised before use.
    bj_stopwatch stopwatch = {0};
 
    // Run for about 3 seconds, measuring the time around each iteration.
    double elapsed = 0.0;
    while (elapsed < 3.0) {
        // Update the stopwatch once per iteration to record the current time.
        // The first call starts the stopwatch.
        bj_step_stopwatch(&stopwatch);
 
        // Total time elapsed since the stopwatch started (first step call).
        elapsed = bj_stopwatch_elapsed(&stopwatch);
 
        // Delta time - time since the previous step. This is crucial for
        // frame-independent movement and animation. For example:
        //   position += velocity * delay;
        // ensures objects move at constant speed regardless of loop rate.
        double delay = bj_stopwatch_delay(&stopwatch);
 
        bj_trace("Elapsed: %.3lf s | Delay: %.3lf s", elapsed, delay);
 
        bj_sleep(300);
    }
 
    bj_end();
    return 0;
}