Play sounds

In this tutorial, we are going to play sounds, multiple sounds in the same time.

Prepare your environment

Do as in Hello World tutorial except that you change the names: playSounds, playSounds.html, playSounds.fg. Copy the files ducks.mp3, birds.mp3, barking.mp3 into the directory playSounds.

Write the program

Write these lines into playSounds.fg:

parallel ||
	playSoundFile('ducks.mp3')
||
	playSoundFile('birds.mp3')
||
	playSoundFile('barking.mp3')

displayNewMessage('The End')

Explanation

This block (that I called 'parallel construct'):

parallel ||
	block1
||
	block2
||
	block3

executes "block1", "block2" and "block3" in parallel (just logical parallelism). Beware that it finished only when all the three blocks are finished.

So when you load playSounds.html, here is the timeline:

Variant #1

If you change a little the program (add exitAfter 2 finished just after the parallel word):

parallel exitAfter 2 finished ||
	playSoundFile('ducks.mp3')
||
	playSoundFile('birds.mp3')
||
	playSoundFile('barking.mp3')

displayNewMessage('The End')

when the two blocks that finished first (playSoundFile('barking.mp3') and playSoundFile('ducks.mp3')) are finished,
all the remaining blocks (in this case, just playSoundFile('birds.mp3')) are discontinued and the parallel construct finishes.
So that the 'The End' message is displayed. Here is the timeline:

Variant #2

If you change again a little the program (put exitWith branch 3 just after the parallel word):

parallel exitWith branch 3 ||
	playSoundFile('ducks.mp3')
||
	playSoundFile('birds.mp3')
||
	playSoundFile('barking.mp3')

displayNewMessage('The End')

when the third (in order of writing) block (playSoundFile('barking.mp3')) is finished,
all the remaining blocks (in this case, playSoundFile('ducks.mp3') and playSoundFile('birds.mp3')) are discontinued and the parallel construct finishes.
So that the 'The End' message is displayed. Here is the timeline: