CSE 203 Closed Lab 9 Instructions

Table of Contents

1. Objectives

To practice using sound in a program, and to see how ClearRectangle() and PrintInRectangle() work together.

2. Set Up

  1. Two students should work together at one workstation.
  2. In one student's account, follow the instructions given below in section 3, Method.  Remember, trading roles (driver and non-driver) for each new session is a very good idea.

3. Method

  1. From the File menu in Phrogram, select New Program (or click the same icon in the toolbar to Create a new program).
  2. Change the program's name to Sound_Test.
  3. Put date and author information in comments at the top of the program.
  4. Type the following two statements inside the Main method:
    Define Test_Sound As Sound
    Test_Sound.LoadFile( "eerie.wav" )
    Test_Sound.Play()
  5. From the File menu, select Save (or click the same icon in the toolbar to Save the active program) and save the program in folder 0) My Own.
  6. Get a "splitter" from a proctor, plug it in, and plug your headphones in.  The proctor has extra headphones if you need to borrow them.
  7. Run the program.
  8. You didn't hear a sound.  That's because the program stopped running immediately after it began playing the sound.  The program can't play a sound when it's not running, and computers are so fast that we couldn't even hear the beginning of the sound before the program stopped running.  Close the window of the stopped program.
  9. We can cause the program to keep running with a call to Delay().  Let's delay for eight seconds.  After "Test_Sound.Play()", type the following statement:
    Delay( 8000 )
  10. Now run the program.  You can hear the sound play for five seconds followed by a couple of clicks, which are an (undesirable) artifact of Phrogram's sound-playing behavior, and about three seconds of silence.  (Close the window of the stopped program.)
  11. Now change "Test_Sound.Play()" to "Test_Sound.PlayLoop()", and run the program. You can hear the sound play for five seconds, then immediately start over, playing just the first three seconds of the sound a second time.  PlayLoop() plays the sound over and over again until it is stopped or the program stops.  (Close the window of the stopped program.)
  12. Two or more sounds can be played simultaneously.  Add the following definition and call to LoadFile() to the beginning of the Main method:
    Define Second_Sound As Sound
    Second_Sound.LoadFile( "SpatialShift.wav" )
  13. Now change PlayLoop() back to Play(), change the 8000 millisecond delay to a 2000 millisecond delay, and add a Play() for Second_Sound and a 5000 millisecond delay, so that the body of the Main method becomes:
    Define Second_Sound As Sound
    Second_Sound.LoadFile( "SpatialShift.wav" )
    Define Test_Sound As Sound
    Test_Sound.LoadFile( "eerie.wav" )
    Test_Sound.Play()
    Delay( 2000 )
    Second_Sound.Play()
    Delay( 5000 )
  14. Run the program.  You can hear SpatialShift play while eerie is playing.  (Close the window of the stopped program.)
  15. You can make that last delay longer, say 15000 milliseconds, and change both calls to Play() to calls to PlayLoop() to hear both of these sounds play over and over together.  Try it!
  16. Of course, we usually don't use such long delays when augmenting interactions with sound.  The file, LOGO_Style_Sprites_W_Sound_N_Msg.kpl plays a sound, yet has only a 15 millisecond delay in its main event loop to keep the program slow enough.  From the Week05 folder in the OSU folder, open and examine file LOGO_Style_Sprites_W_Sound_N_Msg.kpl to see how it starts and stops the sound.
  17. Notice that this program has defined a Boolean object Turn_Sound_Stopped.  A Boolean object can have either of two values: True or False.  The object Turn_Sound_Stopped remembers for us whether it is true that the turn sound has been stopped.
  18. Also notice that, rather strangely, a call to Stop() unloads the sound from the Sound object!  That's bad, but we can overcome this problem by getting in the habit of always calling LoadFile() immediately after calling Stop().
  19. You may also want to notice how this program uses three rectangles to display the rotation message.  Because "Rotation:" and "degrees" only need to be printed to the screen once at the beginning of the program, they each have their own separate rectangle.  This approach also keeps "degrees" from sliding rapidly back and forth as the number of digits of the degree measure changes.  The degree measure is printed in its own rectangle each time through the main event loop.
  20. If you have time, think about your course project.  Consider whether you want to have sound and/or printed rectangles in your course project, and, if so, take the initial steps toward doing so.

4. Proctor Help

If you have a question or get stuck, raise your hand and one of the proctors will come by to chat.