TGE-AUDIO - Audio plugin for TGE

Audio support for TGE runtime - TGE

Based on :

• gomobile exp/audio/al - Copyright (c) 2009 The Go Authors. All rights reserved.
• OpenAL - Copyright (C) 1991 Free Software Foundation, Inc.

The Audio API is based on WebAudio API specifications ported to OpenAL for Desktop and Mobile targets.

Targets

• Desktop (Work In Progress)
• Mobile (Work In Progress)
• Browser

Dependencies

• TGE core

Desktop & Mobile

In order to use this package on Linux desktop distros, you may need OpenAL library as an external dependency:

sudo apt-get install libopenal-dev

Limitations

Only Vorbis format (.ogg) is currently supported for audio files, MP3 will be eventually supported in future releases.

Only StereoPannerNode and GainNode are currently available, additional and custom AudioNodes and spacialization features are planned in future releases.

Audio can't be started without user interaction on browsers, see details in implementation.

Implementation

The WebAudio API offers a complete and comprehensive approach to audio implementation in 2D/3D scenes, tge-audio tries to benefit from it by exposing also OpenAL the same way.

See example at AUDIO examples

package main

import (
	"fmt"
	"time"

	tge "github.com/thommil/tge"
	audio "github.com/thommil/tge-audio"
)

type AudioApp struct {
	runtime                tge.Runtime
	audioInit              bool
	sampleBuffer           audio.Buffer
	stereoPanNode          audio.StereoPannerNode
	gainNode               audio.GainNode
	destinationNode        audio.DestinationNode
	mediaElementSourceNode audio.MediaElementSourceNode
	width                  int32
	height                 int32
}

func (app *AudioApp) OnCreate(settings *tge.Settings) error {
	fmt.Println("OnCreate()")
	settings.Fullscreen = true
	return nil
}

func (app *AudioApp) OnStart(runtime tge.Runtime) error {
	fmt.Println("OnStart()")
	app.runtime = runtime

	runtime.Subscribe(tge.MouseEvent{}.Channel(), app.OnMouseEvent)
	runtime.Subscribe(tge.ResizeEvent{}.Channel(), app.OnResize)
	return nil
}

// InitAudio is start on mouse click only due to browsers restrictions
func (app *AudioApp) InitAudio() error {
	var err error

	//Buffer (should be done in a loading screen off course)
	fmt.Println("Loading left-right.ogg in buffer")
	if app.sampleBuffer, err = audio.CreateBuffer("left-right.ogg"); err != nil {
		return err
	}

	// Audio graph
	fmt.Println("Creating audio graph")
	if app.destinationNode, err = audio.CreateDestinationNode(); err != nil {
		return err
	}
	if app.gainNode, err = audio.CreateGainNode(); err != nil {
		return err
	}
	if app.stereoPanNode, err = audio.CreateStereoPannerNode(); err != nil {
		return err
	}

	app.stereoPanNode.Connect(app.gainNode).Connect(app.destinationNode)

	//Music (should be done in a loading screen off course)
	fmt.Println("Loading music.ogg in media element")
	if app.mediaElementSourceNode, err = audio.CreateMediaElementSourceNode("music.ogg"); err != nil {
		return err
	}

	var mediaElementGainNode audio.GainNode
	if mediaElementGainNode, err = audio.CreateGainNode(); err != nil {
		return err
	}
	mediaElementGainNode.Gain(0.3)
	app.mediaElementSourceNode.Connect(mediaElementGainNode).Connect(app.destinationNode)

	fmt.Println("Start playing music")
	app.mediaElementSourceNode.Play(true)

	app.audioInit = true

	return nil
}

func (app *AudioApp) OnResume() {
	fmt.Println("OnResume()")
	// Open sound
	if app.audioInit {
		app.gainNode.Connect(app.destinationNode)
		app.mediaElementSourceNode.Play(true)
	}
}

func (app *AudioApp) OnResize(event tge.Event) bool {
	app.width = (event.(tge.ResizeEvent)).Width
	app.height = (event.(tge.ResizeEvent)).Height
	return false
}

func (app *AudioApp) OnMouseEvent(event tge.Event) bool {
	mouseEvent := event.(tge.MouseEvent)
	if mouseEvent.Type == tge.TypeDown && (mouseEvent.Button&tge.ButtonLeftOrTouchFirst != 0) {
		if !app.audioInit {
			if err := app.InitAudio(); err != nil {
				fmt.Printf("ERROR: %s\n", err)
			}
		}

		app.stereoPanNode.Pan(float32(mouseEvent.X)/float32(app.width)*2 - 1.0)
		app.gainNode.Gain(float32(app.height-mouseEvent.Y) / float32(app.height))

		fmt.Printf("Set pan to %v and gain to %v%%\n", (float32(mouseEvent.X)/float32(app.width)*2 - 1.0), float32(app.height-mouseEvent.Y)/float32(app.height)*100)

		if sourceNode, err := audio.CreateBufferSourceNode(app.sampleBuffer); err != nil {
			fmt.Printf("ERROR: %s\n", err)
		} else {
			sourceNode.Connect(app.stereoPanNode)
			if mouseEvent.X < app.width/2 {
				// Left chunk
				sourceNode.Start(0, 0, 0.5, false, 0, 0)
			} else {
				// Right chunk
				sourceNode.Start(0, 0.5, 0.5, false, 0, 0)
			}
		}
	}
	return false
}

func (app *AudioApp) OnRender(elaspedTime time.Duration, syncChan <-chan interface{}) {
	<-syncChan
}

func (app *AudioApp) OnTick(elaspedTime time.Duration, syncChan chan<- interface{}) {
	syncChan <- true
}

func (app *AudioApp) OnPause() {
	fmt.Println("OnPause()")
	// Close sound
	if app.audioInit {
		app.gainNode.Disconnect(app.destinationNode)
		app.mediaElementSourceNode.Pause()
	}
}

func (app *AudioApp) OnStop() {
	fmt.Println("OnStop()")
	app.runtime.Unsubscribe(tge.MouseEvent{}.Channel(), app.OnMouseEvent)
	app.runtime.Unsubscribe(tge.ResizeEvent{}.Channel(), app.OnResize)
}

func (app *AudioApp) OnDispose() {
	fmt.Println("OnDispose()")
}

func main() {
	tge.Run(&AudioApp{})
}