systems/delta_time

• C

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  #include <delta_time.h>
  #include <stdio.h>
   
  void PrintDeltaTime(ecs_iter_t *it) {
      // Print delta_time. The same value is passed to all systems.
      printf("delta_time: %f\n", (double)it->delta_time);
  }
   
  int main(int argc, char *argv[]) {
      ecs_world_t *ecs = ecs_init_w_args(argc, argv);
   
      // Create system that prints delta_time. This system doesn't query for any
      // components which means it won't match any entities, but will still be ran
      // once for each call to ecs_progress.
      ECS_SYSTEM(ecs, PrintDeltaTime, EcsOnUpdate, 0);
   
      // Call progress with 0.0f for the delta_time parameter. This will cause
      // ecs_progress to measure the time passed since the last frame. The
      // delta_time of the first frame is a best guess (16ms).
      ecs_progress(ecs, 0.0f);
   
      // The following calls should print a delta_time of approximately 100ms
   
      ecs_os_sleep(0, 100 * 1000 * 1000);
      ecs_progress(ecs, 0.0f);
   
      ecs_os_sleep(0, 100 * 1000 * 1000);
      ecs_progress(ecs, 0.0f);
   
      return ecs_fini(ecs);
  }

• C++

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  #include <delta_time.h>
  #include <iostream>
   
  int main(int, char *[]) {
      flecs::world ecs;
   
      // Create system that prints delta_time. This system doesn't query for any
      // components which means it won't match any entities, but will still be ran
      // once for each call to ecs_progress.
      ecs.system()
          .run([](flecs::iter& it) {
              std::cout << "delta_time: " << it.delta_time() << std::endl;
          });
   
      // Call progress with 0.0f for the delta_time parameter. This will cause
      // ecs_progress to measure the time passed since the last frame. The
      // delta_time of the first frame is a best guess (16ms).
      ecs.progress();
   
      // The following calls should print a delta_time of approximately 100ms
   
      ecs_os_sleep(0, 100 * 1000 * 1000);
      ecs.progress();
   
      ecs_os_sleep(0, 100 * 1000 * 1000);
      ecs.progress();
  }