Audio

Sound

Audio support is provided by the CPSound class.

An instance of CPSound class requires URI of the sound file in one of the supported formats: AIFF, AU or WAV. Sound object is immutable but its playback can be controlled with changing volume, balance, rate, fade in and out. Sounds are inherently asynchronous objects, you can have many sounds objects, all of them are independent of each other, and you can play them in parallel.

Creating A Sound

It is important to note that the game engine must be initialized by calling CPEngine.init(...) methods before sounds object can be created.

Sound objects are created in standard Scala way:

            // Assuming all '*.wav' files are in default '/resources' folder.
            val sndBg = CPSound("background.wav")
            val sndWin = CPSound("win.wav")
            val sndLose = CPSound("lose.wav")
        

Playing A Sound

Once sounds object is created you can easily manipulate its playback. For example:

            sndBg.loop(1500) // Starts indefinite loop with the one-time initial fade in.
            sndWin.play() // Plays the sounds once without a fade in.
        

For the scene-wide sounds like background music you can use lifecycle events of the scene or the lifecycle events of the special invisible scene object to start the playback. Here's an example of using scene's lifecycle events for that:

            val bgPx = CPPixel('.', C_GREY1, C_GREY2)
            val dim = CPDim(100, 50)

            // Assuming all '*.wav' files are in default '/resources' folder.
            val sndBg = CPSound("background.wav")

            object MyScene extends CPScene("id", Option(dim), bgPx):
                private val spr1 = CPAnimationSprite(...)
                private val spr2 = CPAnimationSprite(...)

                addObjects(spr1, spr2)

                // Start the background audio when this scene activates.
                override def onActivate(): Unit =
                    super.onActivate()
                    sndBg.loop(1500) // 1.5sec fade in.

                // Stop the background audio when this scene deactivates.
                override def onDeactivate(): Unit =
                    super.onDeactivate()
                    sndBg.stop(1500) // 1.5sec fade out.
        

NOTES:

• We create background sound object on line 5.
• We start the background sound on line 16 as soon as scene activates with 1.5s fade in effect.
• We stop the background sound on line 21 as soon as scene deactivates with 1.5s fade out effect.
• Note that scene can activate and deactivate multiple times throughout the gameplay.