Part 1 - Basic Loop and infinite loop - The Clock

A. Basic Loop - Spinning clock hands

Do the clock tutorial; 4-3 page 173 in the book with changes below.

• Use the cuckoo clock. Use the Search command to search the gallery if you cannot find it.
• Omit Step 1. You will create the world from scratch.

B. Infinite Loop - The clock pendulum

• The cuckoo clock has a pendulum. Create an infinite loop (using the Loop structure) to cause the pendulum to swing as the hands spin.
  1. Create an infinite loop that rolls the pendulum left, then right in a swinging motion.
  2. Create a Do together block.
  3. Place the original Clock-Hands code and the Pendulum code in the Do together block.
• Play the scene
• Notice that the pendulum continues to swing after the hands are done.

Part 2 - While Loop - Control the pendulum

A while loop is a pretest loop. The while tests a condition, if the condition is true then the loop executes else the loop terminates and the code continues at the line after the loop block. Like the if/else structure, the while uses a condition that will result in a Boolean value of true or false. Modify the above code so that the pendulum stops when the hands finish.

1. Replace the infinite loop with a while loop.
2. Create a Boolean variable to be used in the loop; set the initial value to true.
3. Modify the Clock-Hands block such that the Boolean variable is set to false at the completion of the spin-hands loop

Part 3 - Build a timer

• In class you saw an example of a timer. Now you will build a timer for use in your labs.
• This timer will keep track of the time remaining in some context such as a game.
• Modify the Clock program so that the spin-hands loop has a duration of 1 second per iteration (a pass through the loop). Add a timer display in the lower left-hand corner that counts down from 12 seconds. Start the timer when you start spinning the clock hands.

Create a timer object

1. First, add a 3D text object to the world. Any string of digits could be used. We arbitrarily chose "0.0". Rename the object to timer.
2. Select the timer object and then create a new class variable named timeLeft.
   • The variable is declared to be a Number type.
   • The value is 0 (the game hasn't begun, as yet).
3. At the start of the game, the timer's timeLeft variable must be initialized to the amount of time allowed for playing the game. (This example uses seconds, but minutes would work just as well.) Create a timer.initialize method to set the start time (in this case 12). This method sets the value of timer.timeLeft. This method will need a parameter to pass in the value.
4. Create a timer.countDown method that causes the timer display to count down to 0. Note that timeLeft will have to converted to a string (a built in world function) before it can be displayed as text.

Below is the pseudo code for the timer:

The world.myfirstmethod will use a Do together block start the clock and the countdown timer.

Part 4 - ASSIGNMENT Fixing The Monkey Kicks

You have created a monkey kicking a toyBall in past labs. Modify the code such that the ball moves away when the monkey's foot hits the ball. Use a while loop to control the swing of the monkey's foot. Have the monkey's foot stop swinging forward when the ball is struck.

• Refer to figures 4-40, 4-41, 4-42 and the associated text on page 178 of the book. Recreate the tennis code in a new world to understand how it works.
• In the monkey world set the distance of the monkey to the ball so that the monkey's foot goes through (into) the ball. You have a past lab where you used the distance-to function to have the monkey close to the ball.
• The reaction between the ball and the monkey's foot should be the same as the tennis racquet and the tennis ball.
• Remember to use the monkey's foot in the distance calculation and not the entire monkey.