Outcomes addressed in this activity: Unit Outcomes

• Examine how to combine flow controls to create an animation.
• Identify how to use a function to obtain information about an object and pass that information to a variety of control structures.
• Create an animation that combines various flow control structures and functions.

Course outcome(s) practiced in this unit:

IT111-3: Apply the programming constructs of iteration, assignment and decision-making.

Instructions: Alien Walk

You are going to make an alien walk in Alice. 

1. Get into Alice 3.0. Choose the mars template.
2. Choose Setup Scene. Add an alien object from the Biped folder. Name your alien object anything you want. You may want to rotate the alien to the side so that you can see the leg movements more easily.
3. Feel free to add more objects and props to the alien scene! Although the key focus of this assignment is to implement a walk method, it never hurts to have a fun scene!
4. Save this program as AlienWalk.
5. Click on Edit Code. Select the alien and drag the move method to the editor. Choose forward and 1 meter (thesechoices are known as arguments) to fullfill the direction and amount questions. Click the run button to test your program. 

 

6. Now select the alien’s right hip, by clicking on the object drop down, selecting the arrow to the right of the alien object, and then choosing getRightHip() 

 

7. Next, drag the turn method for the right hip onto the editor under the move method. Choose backward and 0.25 as your arguments. Think of the directions for turning a subpart of an object as clockwise for forward motion and counterclockwise for backward motion. The 0.25 represents the amount that the subpart will turn (1 would be 1 full revolution, therefore 0.25 would ¼th of the way around). Click the run button to test your program. 

 

8. Now have the right knee turn forward 0.25. Remember to think closewise for forward motions and counterclockwise for backwards motions. 

 

9. Click the run button to test your program. This walk looks awkward. You need to fix the timing of these movements. Drag the do together block underneath the move method and then drag the right hip and right knee turn methods in the do together block so that it happen simultaneously. Run your animation again. This should look smoother. 

 

10. Since this leg is raised up, you need to put it back down to create a walking motion. You are going to practice copying the do together block that you already have written to the clipboard. Hold down the ctrl button (command button on the Mac) and drag the do together block to the clipboard  in the right hand corner and release. You should now see a white piece of paper on the clipboard (this indicates that you copied code to the clipboard). If you hover your mouse over the clipboard, you can see the code. (Note: if you do not hold the ctrl button down when you added code to the clipboard, it will cut instead of copying. Click Edit > Undo from the menu if you did a cut.) 

 

11. Hold down the Control key (Command key on Mac) and drag the piece of paper from the clipboard to underneath your first do together block to create a second do together block. Make sure that the second do together block is not inside of the other block. Change the second do together block right hip turn to forward and the right knee turn to backward (click the drop down next to the direction) as shown below: 

 

12. It looks silly that the alien moves forward before his right leg bends. You need him to move forward at the same time that he moves his legs. This is a bit challenging because if you add the move to the first do together, then he will be done moving forward before he puts his leg back down. If you combine the 2 do together, then he will not bend his leg at all because the forward and backwards motions will cancel each other out. You need to move the 2 do together blocks into a do in order block and then have the do in order block happening at the same time as the move method. This may take some practice. If you make a mistake click Edit on the menu bar and then Undo. 

 

WOW! Walking is harder than you imagined! 

13. You may want to change the duration of the move to be 2 seconds instead of 1 second (default). Since the first do together block will take 1 second and the second do together block will take 1 second, it would be nice if the move took the same amount of time as both do together blocks added together (which would be 2 seconds). 

 

14. Repeat the code for the left hip and left knee to create a walking motion. Hint: use the clipboard to copy the code that you already have and then change the body part to be left hip and left knee. The code is shown below if you need some help. 

 

15. Run your animation. It looks good!
16. Convert the walk() method to a scene method so that it can be called by other biped objects. Add a second biped object to the scene and call the scene walk() method for that second biped object. 

Requirements: 

1. 1. Create a method that allows the alien to walk with realistic movements.
   2. Effectively use the clipboard to copy and then modify methods for the right leg to work like the left leg.
   3. Coordinate forward movement with the individual leg movements to create a realistic Walk() method.
   4. Add a loop method to control how many steps the alien takes.
   5. Convert the class method, Walk(), to a scene method. Add a second biped object and call the scene method, Walk(), for the second object.