text: /*************************************************************************/
  /*  audio_stream_player_2d.cpp                                           */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "audio_stream_player_2d.h"
  
  #include "core/engine.h"
  #include "scene/2d/area_2d.h"
  #include "scene/main/viewport.h"
  
  void AudioStreamPlayer2D::_mix_audio() {
  
  	if (!stream_playback.is_valid() || !active ||
  			(stream_paused && !stream_paused_fade_out)) {
  		return;
  	}
  
  	if (setseek >= 0.0) {
  		stream_playback->start(setseek);
  		setseek = -1.0; //reset seek
  	}
  
  	//get data
  	AudioFrame *buffer = mix_buffer.ptrw();
  	int buffer_size = mix_buffer.size();
  
  	if (stream_paused_fade_out) {
  		// Short fadeout ramp
  		buffer_size = MIN(buffer_size, 128);
  	}
  
  	stream_playback->mix(buffer, pitch_scale, buffer_size);
  
  	//write all outputs
  	for (int i = 0; i < output_count; i++) {
  
  		Output current = outputs[i];
  
  		//see if current output exists, to keep volume ramp
  		bool found = false;
  		for (int j = i; j < prev_output_count; j++) {
  			if (prev_outputs[j].viewport == current.viewport) {
  				if (j != i) {
  					SWAP(prev_outputs[j], prev_outputs[i]);
  				}
  				found = true;
  				break;
  			}
  		}
  
  		if (!found) {
  			//create new if was not used before
  			if (prev_output_count < MAX_OUTPUTS) {
  				prev_outputs[prev_output_count] = prev_outputs[i]; //may be owned by another viewport
  				prev_output_count++;
  			}
  			prev_outputs[i] = current;
  		}
  
  		//mix!
  		AudioFrame target_volume = stream_paused_fade_out ? AudioFrame(0.f, 0.f) : current.vol;
  		AudioFrame vol_prev = stream_paused_fade_in ? AudioFrame(0.f, 0.f) : prev_outputs[i].vol;
  		AudioFrame vol_inc = (target_volume - vol_prev) / float(buffer_size);
  		AudioFrame vol = stream_paused_fade_in ? AudioFrame(0.f, 0.f) : current.vol;
  
  		int cc = AudioServer::get_singleton()->get_channel_count();
  
  		if (cc == 1) {
  			if (!AudioServer::get_singleton()->thread_has_channel_mix_buffer(current.bus_index, 0))
  				continue; //may have been removed
  
  			AudioFrame *target = AudioServer::get_singleton()->thread_get_channel_mix_buffer(current.bus_index, 0);
  
  			for (int j = 0; j < buffer_size; j++) {
  
  				target[j] += buffer[j] * vol;
  				vol += vol_inc;
  			}
  
  		} else {
  			AudioFrame *targets[4];
  			bool valid = true;
  
  			for (int k = 0; k < cc; k++) {
  				if (!AudioServer::get_singleton()->thread_has_channel_mix_buffer(current.bus_index, k)) {
  					valid = false; //may have been removed
  					break;
  				}
  
  				targets[k] = AudioServer::get_singleton()->thread_get_channel_mix_buffer(current.bus_index, k);
  			}
  
  			if (!valid)
  				continue;
  
  			for (int j = 0; j < buffer_size; j++) {
  
  				AudioFrame frame = buffer[j] * vol;
  				for (int k = 0; k < cc; k++) {
  					targets[k][j] += frame;
  				}
  				vol += vol_inc;
  			}
  		}
  
  		prev_outputs[i] = current;
  	}
  
  	prev_output_count = output_count;
  
  	//stream is no longer active, disable this.
  	if (!stream_playback->is_playing()) {
  		active = false;
  	}
  
  	output_ready = false;
  	stream_paused_fade_in = false;
  	stream_paused_fade_out = false;
  }
  
  void AudioStreamPlayer2D::_notification(int p_what) {
  
  	if (p_what == NOTIFICATION_ENTER_TREE) {
  
  		AudioServer::get_singleton()->add_callback(_mix_audios, this);
  		if (autoplay && !Engine::get_singleton()->is_editor_hint()) {
  			play();
  		}
  	}
  
  	if (p_what == NOTIFICATION_EXIT_TREE) {
  
  		AudioServer::get_singleton()->remove_callback(_mix_audios, this);
  	}
  
  	if (p_what == NOTIFICATION_PAUSED) {
  		if (!can_process()) {
  			// Node can't process so we start fading out to silence
  			set_stream_paused(true);
  		}
  	}
  
  	if (p_what == NOTIFICATION_UNPAUSED) {
  		set_stream_paused(false);
  	}
  
  	if (p_what == NOTIFICATION_INTERNAL_PHYSICS_PROCESS) {
  
  		//update anything related to position first, if possible of course
  
  		if (!output_ready) {
  			List<Viewport *> viewports;
  			Ref<World2D> world_2d = get_world_2d();
  			ERR_FAIL_COND(world_2d.is_null());
  
  			int new_output_count = 0;
  
  			Vector2 global_pos = get_global_position();
  
  			int bus_index = AudioServer::get_singleton()->thread_find_bus_index(bus);
  
  			//check if any area is diverting sound into a bus
  
  			Physics2DDirectSpaceState *space_state = Physics2DServer::get_singleton()->space_get_direct_state(world_2d->get_space());
  
  			Physics2DDirectSpaceState::ShapeResult sr[MAX_INTERSECT_AREAS];
  
  			int areas = space_state->intersect_point(global_pos, sr, MAX_INTERSECT_AREAS, Set<RID>(), area_mask, false, true);
  
  			for (int i = 0; i < areas; i++) {
  
  				Area2D *area2d = Object::cast_to<Area2D>(sr[i].collider);
  				if (!area2d)
  					continue;
  
  				if (!area2d->is_overriding_audio_bus())
  					continue;
  
  				StringName bus_name = area2d->get_audio_bus_name();
  				bus_index = AudioServer::get_singleton()->thread_find_bus_index(bus_name);
  				break;
  			}
  
  			world_2d->get_viewport_list(&viewports);
  			for (List<Viewport *>::Element *E = viewports.front(); E; E = E->next()) {
  
  				Viewport *vp = E->get();
  				if (vp->is_audio_listener_2d()) {
  
  					//compute matrix to convert to screen
  					Transform2D to_screen = vp->get_global_canvas_transform() * vp->get_canvas_transform();
  					Vector2 screen_size = vp->get_visible_rect().size;
  
  					//screen in global is used for attenuation
  					Vector2 screen_in_global = to_screen.affine_inverse().xform(screen_size * 0.5);
  
  					float dist = global_pos.distance_to(screen_in_global); //distance to screen center
  
  					if (dist > max_distance)
  						continue; //can't hear this sound in this viewport
  
  					float multiplier = Math::pow(1.0f - dist / max_distance, attenuation);
  					multiplier *= Math::db2linear(volume_db); //also apply player volume!
  
  					//point in screen is used for panning
  					Vector2 point_in_screen = to_screen.xform(global_pos);
  
  					float pan = CLAMP(point_in_screen.x / screen_size.width, 0.0, 1.0);
  
  					float l = 1.0 - pan;
  					float r = pan;
  
  					outputs[new_output_count].vol = AudioFrame(l, r) * multiplier;
  					outputs[new_output_count].bus_index = bus_index;
  					outputs[new_output_count].viewport = vp; //keep pointer only for reference
  					new_output_count++;
  					if (new_output_count == MAX_OUTPUTS)
  						break;
  				}
  			}
  
  			output_count = new_output_count;
  			output_ready = true;
  		}
  
  		//start playing if requested
  		if (setplay >= 0.0) {
  			setseek = setplay;
  			active = true;
  			setplay = -1;
  			//do not update, this makes it easier to animate (will shut off otherwise)
  			//_change_notify("playing"); //update property in editor
  		}
  
  		//stop playing if no longer active
  		if (!active) {
  			set_physics_process_internal(false);
  			//do not update, this makes it easier to animate (will shut off otherwise)
  			//_change_notify("playing"); //update property in editor
  			emit_signal("finished");
  		}
  	}
  }
  
  void AudioStreamPlayer2D::set_stream(Ref<AudioStream> p_stream) {
  
  	AudioServer::get_singleton()->lock();
  
  	mix_buffer.resize(AudioServer::get_singleton()->thread_get_mix_buffer_size());
  
  	if (stream_playback.is_valid()) {
  		stream_playback.unref();
  		stream.unref();
  		active = false;
  		setseek = -1;
  	}
  
  	if (p_stream.is_valid()) {
  		stream = p_stream;
  		stream_playback = p_stream->instance_playback();
  	}
  
  	AudioServer::get_singleton()->unlock();
  
  	if (p_stream.is_valid() && stream_playback.is_null()) {
  		stream.unref();
  	}
  }
  
  Ref<AudioStream> AudioStreamPlayer2D::get_stream() const {
  
  	return stream;
  }
  
  void AudioStreamPlayer2D::set_volume_db(float p_volume) {
  
  	volume_db = p_volume;
  }
  float AudioStreamPlayer2D::get_volume_db() const {
  
  	return volume_db;
  }
  
  void AudioStreamPlayer2D::set_pitch_scale(float p_pitch_scale) {
  	ERR_FAIL_COND(p_pitch_scale <= 0.0);
  	pitch_scale = p_pitch_scale;
  }
  float AudioStreamPlayer2D::get_pitch_scale() const {
  	return pitch_scale;
  }
  
  void AudioStreamPlayer2D::play(float p_from_pos) {
  
  	if (!is_playing()) {
  		// Reset the prev_output_count if the stream is stopped
  		prev_output_count = 0;
  	}
  
  	if (stream_playback.is_valid()) {
  		active = true;
  		setplay = p_from_pos;
  		output_ready = false;
  		set_physics_process_internal(true);
  	}
  }
  
  void AudioStreamPlayer2D::seek(float p_seconds) {
  
  	if (stream_playback.is_valid()) {
  		setseek = p_seconds;
  	}
  }
  
  void AudioStreamPlayer2D::stop() {
  
  	if (stream_playback.is_valid()) {
  		active = false;
  		set_physics_process_internal(false);
  		setplay = -1;
  	}
  }
  
  bool AudioStreamPlayer2D::is_playing() const {
  
  	if (stream_playback.is_valid()) {
  		return active; // && stream_playback->is_playing();
  	}
  
  	return false;
  }
  
  float AudioStreamPlayer2D::get_playback_position() {
  
  	if (stream_playback.is_valid()) {
  		return stream_playback->get_playback_position();
  	}
  
  	return 0;
  }
  
  void AudioStreamPlayer2D::set_bus(const StringName &p_bus) {
  
  	//if audio is active, must lock this
  	AudioServer::get_singleton()->lock();
  	bus = p_bus;
  	AudioServer::get_singleton()->unlock();
  }
  StringName AudioStreamPlayer2D::get_bus() const {
  
  	for (int i = 0; i < AudioServer::get_singleton()->get_bus_count(); i++) {
  		if (AudioServer::get_singleton()->get_bus_name(i) == bus) {
  			return bus;
  		}
  	}
  	return "Master";
  }
  
  void AudioStreamPlayer2D::set_autoplay(bool p_enable) {
  
  	autoplay = p_enable;
  }
  bool AudioStreamPlayer2D::is_autoplay_enabled() {
  
  	return autoplay;
  }
  
  void AudioStreamPlayer2D::_set_playing(bool p_enable) {
  
  	if (p_enable)
  		play();
  	else
  		stop();
  }
  bool AudioStreamPlayer2D::_is_active() const {
  
  	return active;
  }
  
  void AudioStreamPlayer2D::_validate_property(PropertyInfo &property) const {
  
  	if (property.name == "bus") {
  
  		String options;
  		for (int i = 0; i < AudioServer::get_singleton()->get_bus_count(); i++) {
  			if (i > 0)
  				options += ",";
  			String name = AudioServer::get_singleton()->get_bus_name(i);
  			options += name;
  		}
  
  		property.hint_string = options;
  	}
  }
  
  void AudioStreamPlayer2D::_bus_layout_changed() {
  
  	_change_notify();
  }
  
  void AudioStreamPlayer2D::set_max_distance(float p_pixels) {
  
  	ERR_FAIL_COND(p_pixels <= 0.0);
  	max_distance = p_pixels;
  }
  
  float AudioStreamPlayer2D::get_max_distance() const {
  
  	return max_distance;
  }
  
  void AudioStreamPlayer2D::set_attenuation(float p_curve) {
  
  	attenuation = p_curve;
  }
  float AudioStreamPlayer2D::get_attenuation() const {
  
  	return attenuation;
  }
  
  void AudioStreamPlayer2D::set_area_mask(uint32_t p_mask) {
  
  	area_mask = p_mask;
  }
  
  uint32_t AudioStreamPlayer2D::get_area_mask() const {
  
  	return area_mask;
  }
  
  void AudioStreamPlayer2D::set_stream_paused(bool p_pause) {
  
  	if (p_pause != stream_paused) {
  		stream_paused = p_pause;
  		stream_paused_fade_in = !p_pause;
  		stream_paused_fade_out = p_pause;
  	}
  }
  
  bool AudioStreamPlayer2D::get_stream_paused() const {
  
  	return stream_paused;
  }
  
  Ref<AudioStreamPlayback> AudioStreamPlayer2D::get_stream_playback() {
  	return stream_playback;
  }
  
  void AudioStreamPlayer2D::_bind_methods() {
  
  	ClassDB::bind_method(D_METHOD("set_stream", "stream"), &AudioStreamPlayer2D::set_stream);
  	ClassDB::bind_method(D_METHOD("get_stream"), &AudioStreamPlayer2D::get_stream);
  
  	ClassDB::bind_method(D_METHOD("set_volume_db", "volume_db"), &AudioStreamPlayer2D::set_volume_db);
  	ClassDB::bind_method(D_METHOD("get_volume_db"), &AudioStreamPlayer2D::get_volume_db);
  
  	ClassDB::bind_method(D_METHOD("set_pitch_scale", "pitch_scale"), &AudioStreamPlayer2D::set_pitch_scale);
  	ClassDB::bind_method(D_METHOD("get_pitch_scale"), &AudioStreamPlayer2D::get_pitch_scale);
  
  	ClassDB::bind_method(D_METHOD("play", "from_position"), &AudioStreamPlayer2D::play, DEFVAL(0.0));
  	ClassDB::bind_method(D_METHOD("seek", "to_position"), &AudioStreamPlayer2D::seek);
  	ClassDB::bind_method(D_METHOD("stop"), &AudioStreamPlayer2D::stop);
  
  	ClassDB::bind_method(D_METHOD("is_playing"), &AudioStreamPlayer2D::is_playing);
  	ClassDB::bind_method(D_METHOD("get_playback_position"), &AudioStreamPlayer2D::get_playback_position);
  
  	ClassDB::bind_method(D_METHOD("set_bus", "bus"), &AudioStreamPlayer2D::set_bus);
  	ClassDB::bind_method(D_METHOD("get_bus"), &AudioStreamPlayer2D::get_bus);
  
  	ClassDB::bind_method(D_METHOD("set_autoplay", "enable"), &AudioStreamPlayer2D::set_autoplay);
  	ClassDB::bind_method(D_METHOD("is_autoplay_enabled"), &AudioStreamPlayer2D::is_autoplay_enabled);
  
  	ClassDB::bind_method(D_METHOD("_set_playing", "enable"), &AudioStreamPlayer2D::_set_playing);
  	ClassDB::bind_method(D_METHOD("_is_active"), &AudioStreamPlayer2D::_is_active);
  
  	ClassDB::bind_method(D_METHOD("set_max_distance", "pixels"), &AudioStreamPlayer2D::set_max_distance);
  	ClassDB::bind_method(D_METHOD("get_max_distance"), &AudioStreamPlayer2D::get_max_distance);
  
  	ClassDB::bind_method(D_METHOD("set_attenuation", "curve"), &AudioStreamPlayer2D::set_attenuation);
  	ClassDB::bind_method(D_METHOD("get_attenuation"), &AudioStreamPlayer2D::get_attenuation);
  
  	ClassDB::bind_method(D_METHOD("set_area_mask", "mask"), &AudioStreamPlayer2D::set_area_mask);
  	ClassDB::bind_method(D_METHOD("get_area_mask"), &AudioStreamPlayer2D::get_area_mask);
  
  	ClassDB::bind_method(D_METHOD("set_stream_paused", "pause"), &AudioStreamPlayer2D::set_stream_paused);
  	ClassDB::bind_method(D_METHOD("get_stream_paused"), &AudioStreamPlayer2D::get_stream_paused);
  
  	ClassDB::bind_method(D_METHOD("get_stream_playback"), &AudioStreamPlayer2D::get_stream_playback);
  
  	ClassDB::bind_method(D_METHOD("_bus_layout_changed"), &AudioStreamPlayer2D::_bus_layout_changed);
  
  	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "stream", PROPERTY_HINT_RESOURCE_TYPE, "AudioStream"), "set_stream", "get_stream");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "volume_db", PROPERTY_HINT_RANGE, "-80,24"), "set_volume_db", "get_volume_db");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "pitch_scale", PROPERTY_HINT_RANGE, "0.01,32,0.01"), "set_pitch_scale", "get_pitch_scale");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "playing", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_EDITOR), "_set_playing", "is_playing");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "autoplay"), "set_autoplay", "is_autoplay_enabled");
  	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "stream_paused", PROPERTY_HINT_NONE, ""), "set_stream_paused", "get_stream_paused");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "max_distance", PROPERTY_HINT_EXP_RANGE, "1,4096,1,or_greater"), "set_max_distance", "get_max_distance");
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "attenuation", PROPERTY_HINT_EXP_EASING, "attenuation"), "set_attenuation", "get_attenuation");
  	ADD_PROPERTY(PropertyInfo(Variant::STRING, "bus", PROPERTY_HINT_ENUM, ""), "set_bus", "get_bus");
  	ADD_PROPERTY(PropertyInfo(Variant::INT, "area_mask", PROPERTY_HINT_LAYERS_2D_PHYSICS), "set_area_mask", "get_area_mask");
  
  	ADD_SIGNAL(MethodInfo("finished"));
  }
  
  AudioStreamPlayer2D::AudioStreamPlayer2D() {
  
  	volume_db = 0;
  	pitch_scale = 1.0;
  	autoplay = false;
  	setseek = -1;
  	active = false;
  	output_count = 0;
  	prev_output_count = 0;
  	max_distance = 2000;
  	attenuation = 1;
  	setplay = -1;
  	output_ready = false;
  	area_mask = 1;
  	stream_paused = false;
  	stream_paused_fade_in = false;
  	stream_paused_fade_out = false;
  	AudioServer::get_singleton()->connect("bus_layout_changed", this, "_bus_layout_changed");
  }
  
  AudioStreamPlayer2D::~AudioStreamPlayer2D() {
  }
  