diff --git a/main/main.cpp b/main/main.cpp index 94dd895a264b..610a6ed672a9 100644 --- a/main/main.cpp +++ b/main/main.cpp @@ -2258,25 +2258,37 @@ bool Main::iteration() { return exit; } - if (OS::get_singleton()->is_in_low_processor_usage_mode() || !DisplayServer::get_singleton()->can_any_window_draw()) { - OS::get_singleton()->delay_usec(OS::get_singleton()->get_low_processor_usage_mode_sleep_usec()); //apply some delay to force idle time - } else { - uint32_t frame_delay = Engine::get_singleton()->get_frame_delay(); - if (frame_delay) { - OS::get_singleton()->delay_usec(Engine::get_singleton()->get_frame_delay() * 1000); - } + const uint32_t frame_delay = Engine::get_singleton()->get_frame_delay(); + if (frame_delay) { + // Add fixed frame delay to decrease CPU/GPU usage. This doesn't take + // the actual frame time into account. + // Due to the high fluctuation of the actual sleep duration, it's not recommended + // to use this as a FPS limiter. + OS::get_singleton()->delay_usec(frame_delay * 1000); + } + + // Add a dynamic frame delay to decrease CPU/GPU usage. This takes the + // previous frame time into account for a smoother result. + uint64_t dynamic_delay = 0; + if (OS::get_singleton()->is_in_low_processor_usage_mode() || !DisplayServer::get_singleton()->window_can_draw()) { + dynamic_delay = OS::get_singleton()->get_low_processor_usage_mode_sleep_usec(); + } + const int target_fps = Engine::get_singleton()->get_target_fps(); + if (target_fps > 0 && !Engine::get_singleton()->is_editor_hint()) { + // Override the low processor usage mode sleep delay if the target FPS is lower. + dynamic_delay = MAX(dynamic_delay, (uint64_t)(1000000 / target_fps)); } - int target_fps = Engine::get_singleton()->get_target_fps(); - if (target_fps > 0 && !Engine::get_singleton()->is_editor_hint()) { - uint64_t time_step = 1000000L / target_fps; - target_ticks += time_step; + if (dynamic_delay > 0) { + target_ticks += dynamic_delay; uint64_t current_ticks = OS::get_singleton()->get_ticks_usec(); + if (current_ticks < target_ticks) { OS::get_singleton()->delay_usec(target_ticks - current_ticks); } + current_ticks = OS::get_singleton()->get_ticks_usec(); - target_ticks = MIN(MAX(target_ticks, current_ticks - time_step), current_ticks + time_step); + target_ticks = MIN(MAX(target_ticks, current_ticks - dynamic_delay), current_ticks + dynamic_delay); } #ifdef TOOLS_ENABLED