![]() ![]() ![]() There is a way to create an Actor or World object that does not belong to any pre-defined subclass even though those classes are abstract. Thought of the day: how can a program ever return a false value when asked if it is running? (if it is not running, then what is causing the statement to be executed). Anyway, it is nothing like the 'isPlaying' method. There may be instances where you may want to call it however, it is mainly called internally by greenfoot when the 'Pause' button is clicked or a 'Greenfoot.stop()' method is executed (when the scenario goes from a running state to a stopped state). Finally, the 'stopped' method is usually not called explicitly. Second, the return type of the 'stopped' method is void, meaning that it will not return a true/false value. This means you must supply a world object to execute the method on (which world object is the method being called on). After using them for a while, you will be surprised that you found them so difficult at first.ġ13 7.First, the 'stopped' method is not a static method. The more practice you get, the easier it becomes. Understanding lists and loops is initially quite difficult, but very important in programming, so you should carefully review these aspects of your code if you are not yet comfortable in using them. */ private void createStars(int number) else // Splitting an Asteroid is worth 10 points int r = getMovement().getDirection() + Greenfoot.getRandomNumber(45) double l = getMovement().getLength() Vector speed1 = new Vector(r + 60, l * 1.2) Vector speed2 = new Vector(r - 60, l * 1.2) Asteroid a1 = new Asteroid(size/2, speed1) Asteroid a2 = new Asteroid(size/2, speed2) getWorld().addObject(a1, getX(), getY()) getWorld().addObject(a2, getX(), getY()) a1.move() a2.move() untScore(10) ġ12 7.11 Summary of Programming Techniques A world that does not have a background image assigned will, by default, get an automatically created background image that is filled with plain white.ĩ The Background is Created by These Three StatementsĮxercise 7.6 The Background is Created by These Three Statementsġ0 Code to Create the Background is Commented OutĮxercise 7.7 Code to Create the Background is Commented Outġ2 Exercise 7.8 Draw Oval Draw Rectangle Fill Ovalġ8 Exercise 7.10 /* * Method to create stars. Just remove the eat method (and the call to it from the act method) and add the command to play the slurp in the lookforcrab method. ![]() The ScoreBoard, Explosion, and ProtonWave classes, which we can see in the class diagram, do not seem to feature in the scenario.Ĥ Exercise 7.2 Controls for the Rocket Collision Logic Explosion LogicĮxercise 7.3 Spacebar is used to fire a bulletĦ Creates the Explosion Visual and makes and Explosion SoundĮxercise 7.4 Creates the Explosion Visual and makes and Explosion Soundħ The visual is Present, But It Does Not Do AnythingĮxercise 7.5 The visual is Present, But It Does Not Do AnythingĨ 7.2 Painting Stars The Asteroid Scenario does not use an image file for the background. You are calling lookforcrab which will eat the worm without sound then, you are calling eat which would (if a crab was left to eat) make a sound when eating. The game never ends, and a final score is never displayed. It flies straight through it, instead of damaging the rocket. Nothing happens when an asteroid collides with the rocket. It cannot be turned, nor can it be moved forward. When experimenting with the current scenario, you will notice that some fundamental functionality is missing. ![]() 1 Chapter 7 - Collision Detection: Asteroids ![]()
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