systems/target_fps

• C

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  #include <target_fps.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);
   
      // Set target FPS to 1 frame per second
      ecs_set_target_fps(ecs, 1);
   
      // Run 5 frames
      for (int i = 0; i < 5; i ++) {
          // To make sure the frame doesn't run faster than the specified target
          // FPS ecs_progress will insert a sleep if the measured delta_time is
          // smaller than 1 / target_fps.
          //
          // By default ecs_progress uses the sleep function provided by the OS
          // which is not always very accurate. If more accuracy is required the
          // sleep function of the OS API can be overridden with a custom one.
          //
          // If a value other than 0 is provided to the delta_time argument of
          // ecs_progress, this value will be used to calculate the length of
          // the sleep to insert.
          ecs_progress(ecs, 0);
      }
   
      return ecs_fini(ecs);
  }

• C++

  View on GitHub

  #include <target_fps.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;
          });
   
      // Set target FPS to 1 frame per second
      ecs.set_target_fps(1);
   
      // Run 5 frames
      for (int i = 0; i < 5; i ++) {
          // To make sure the frame doesn't run faster than the specified target
          // FPS ecs_progress will insert a sleep if the measured delta_time is
          // smaller than 1 / target_fps.
          //
          // By default ecs_progress uses the sleep function provided by the OS
          // which is not always very accurate. If more accuracy is required the
          // sleep function of the OS API can be overridden with a custom one.
          //
          // If a value other than 0 is provided to the delta_time argument of
          // ecs_progress, this value will be used to calculate the length of
          // the sleep to insert.
          ecs.progress();
      }
  }