Feature Reference - The Game Maker's Companion: Game Development - page 382

4. Add another Script resource called music_toggle and insert the following lines:
1: {
2: global.playmusic = !global.playmusic;
3: if ( global.playmusic ) sound_play(global.music)
4: else sound_stop(global.music);
5: image_index = global.playmusic;

6: }

The value of global.playmusic should either be 1 (true) or 0 (false). Rather than using
an if statement to check and change, we're using the Boolean operator ! ( NOT ),
because it flips the value around for us. Line 3 checks if we should either play or stop
playing the music (line 4) and line 5 changes the subimage.
5. Open obj_music_toggle again and add a Mouse , Left pressed event. Insert an Execute
Script action and set Script to music_toggle .
6. Add a Key Press event for the letter M and include another Execute Script action.
Again, set Script to music_toggle . We can now either click the object or press the M
key to toggle the music.
7. Place an instance of obj_music_toggle in the top-right of the test room.
8. It can't work without any music, so we need to make sure we play some music in the
same room. Open obj_spaceship and add an Other , Room Start event. We use this
event because it is executed after all Create events have been handled, so the
global.playmusic variable will already have a value. Here comes the most important
part—we're no longer going to use the Play Sound action to play sounds or music.
Include an Execute Script event and set Script to music_play . Set Argument0 to
snd_music . Notice there is no longer a drop-down menu, so we'll have to enter the
correct values ourselves.
9. Now, add an object called obj_sfx_toggle , set the Sprite to spr_sfx_toggle , and the
Depth to -1000 . The toggle for sound effects works in much the same way as
obj_music_toggle , as you'll see shortly.
10. Add a Create event, include an Execute Code action, and insert the following lines:
1: {
2: if ( !variable_global_exists('playsfx') ) global.playsfx = true;
3: image_index = global.playsfx;
4: image_speed = 0;
5: }

11. Add another Script resource and call it sfx_toggle . Insert the following lines:
1: {
2: global.playsfx = !global.playsfx;
3: image_index = global.playsfx;
4: }