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.

#define BJ_AUTOMAIN_CALLBACKS
#include <banjo/log.h>
#include <banjo/main.h>
#include <banjo/system.h>
#include <banjo/time.h>
 
// A stopwatch must be zero-initialized before use.
static bj_stopwatch p_stopwatch = {0};
 
int bj_app_begin(void** user_data, int argc, char* argv[]) {
    (void)user_data; (void)argc; (void)argv;
 
    if (!bj_begin(BJ_NO_SYSTEM, 0)) {
        return bj_callback_exit_error;
    }
 
    return bj_callback_continue;
}
 
int bj_app_iterate(void* user_data) {
    (void)user_data;
 
    // Update the stopwatch. This must be called once per iteration to record
    // the current time. The first call starts the stopwatch.
    bj_step_stopwatch(&p_stopwatch);
 
    // Get total time elapsed since the stopwatch started (first step call).
    double elapsed = bj_stopwatch_elapsed(&p_stopwatch);
 
    // Get 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 frame rate.
    double delay   = bj_stopwatch_delay(&p_stopwatch);
 
    bj_trace("Elapsed: %.3lf s | Delay: %.3lf s", elapsed, delay);
 
    bj_sleep(300);
    return elapsed >= 3.0 ? bj_callback_exit_success : bj_callback_continue;
}
 
int bj_app_end(void* user_data, int status) {
    (void)user_data;
    bj_end();
    return status;
}