Transcript Lab7_Asteroid
Asteroids Games and Simulations O-O Programming in Java The Walker School The Walker School – Games and Simulations - 2010
Asteroids Take some time to play with Asteroids. What can the program do and what can’t it do?
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Discovering Keyboard Controls Which keyboard key is used to fire a bullet?
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Explosions Place an explosion into a running scenario. Does it work? What does it do?
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Painting Stars The Walker School – Games and Simulations - 2010
Create a New Scenario Directions 1. Create a new scenario.
2. Save it as “asteriods-lastname”.
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Create the World Directions 1. Create a new subClass called “Space”.
2. Leave the background empty.
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Enlarge the Background Directions: 1. Change the size of the world (600, 400, 1).
2. Change the comment.
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Painting Backgrounds Part IV http://www.youtube.com/watch?v=rvZ0ErpfHKM&feature=related The Walker School – Games and Simulations - 2010
Import the Java Color Library The Walker School – Games and Simulations - 2010
Use Java to Paint Black Background The Walker School – Games and Simulations - 2010
Create a method createStars() Comment it out until we create the method.
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Create a Method Body Takes a parameter of type integer, as we stated we wanted 300 stars.
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Create The Stars Step through this loop and explain what is happening.
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For Loops } { for (initialization; loop-condition; increment)
loop-body;
• The initialization part declares and initializes a loop variable. This variable is often called i, and often initialized to 0.
• The loop condition checks whether our loop variable is still less than a given limit. If it is, the loop will continue.
• The increment section simply increments the loop variable.
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Vary Star Brightness The Walker School – Games and Simulations - 2010
Rocket Firing The Walker School – Games and Simulations - 2010
Turning The Walker School – Games and Simulations - 2010
Flying Forward The Walker School – Games and Simulations - 2010
Flying Forward Calls the move() method from SmoothMover class.
What happens?
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• • • • • What Do We Need To Do?
So where are we going to do this?
Add initial movement to the rocket. To add movement, we need to add force to the rocket.
And we need to change its vector.
So we’ll need to call this vector from the Vector abstract class.
The vector needs 2 variables: direction (dy) and length (dx).
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Adding Drift What happens when you change the variables in the vector?
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What Do We Need To Do?
• • • Create variables to handle each rocket image. Add a method called ignite to checkKeys(), so that we when hit the “up” button, the rocket image is changed.
Define a method called ignite. It will need a boolean parameter and a void return type.
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Create a Method Stub to Ignite Rocket Remember to create an instance variable called boosterOn.
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Igniting the Rocket Boosters The Walker School – Games and Simulations - 2010
Colliding with Asteroids The Walker School – Games and Simulations - 2010
What Do We Need to Do?
• • • • If we collide with an asteroid, Remove the rocket from the world; Place an explosion into the world; Show final score (game over); The Walker School – Games and Simulations - 2010
Methods for Collision Detection file:///C:/Greenfoot/doc/API/index.html
Both methods accept a parameter of type Class, which means we can check for intersections with a specific class of objects if we want to.
Which of these 2 methods do we want to use and why?
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Colliding with Asteroids Remember to call the method in the rocket act() method.
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Creating Better Explosions • • • • • Part I http://www.youtube.com/watch?v=rgZ-_vQ2aIc Part II Part III http://www.youtube.com/watch?v=bdv4ZgTcYyY&feature=related http://www.youtube.com/watch?v=OFuDEt0xifM&feature=related Part IV http://www.youtube.com/watch?v=XMJi4_bzuLw&feature=related Part V http://www.youtube.com/watch?v=TKYwL8p_11A&feature=related The Walker School – Games and Simulations - 2010
What Do We Need To Do?
• • • Add abstract classes SmoothMover and Vector from Greenfoot.
Create a constructor for Debris Update the move() method
Casting The Walker School – Games and Simulations - 2010
Create the Score Board The Walker School – Games and Simulations - 2010
Import Java Libraries The Walker School – Games and Simulations - 2010
Create the Assignment Variables The Walker School – Games and Simulations - 2010
Create the Constructors Why are their 2 constructors?
How is this an example of overloading?
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Make Scoreboard Image So, what else needs to be done?
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Activity – Change Attributes • Modify the ScoreBoard class: – Change the text shown on it.
– Change the color of the text.
– Change the background and frame colors.
– Change the font size so that your text fits well.
– Change the width of the scoreboard to suit your text.
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Homework – Scoreboard • Search the Greenfoot library for other games that have scoreboards. Study how they were built. What attributes do they have that this board does not? What could you add to your scoreboard?
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Add a Variable for the Counter The Walker School – Games and Simulations - 2010
Assign the Counter to the Constructor The Walker School – Games and Simulations - 2010
Call the Counter When Game Over How can you make sure that the counter is in the middle of the board without hard coding the numbers? The Walker School – Games and Simulations - 2010
Ensure the Scoreboard is in the Middle of the Background Where do we call the gameOver() method? The Walker School – Games and Simulations - 2010
Call the Game Over Method Example of Casting The Walker School – Games and Simulations - 2010
Casting • • Casting is the technique of telling the compiler a more precise type for our object then it can work out for itself. We do this by writing the class name (Space) in parentheses before the method call. Once we have done this we can call methods defined in Space space.gameOver(); Casting does not change the type of the object returned.
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Add a Proton Wave What does it do?
What doesn’t it do?
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Import the Library We are going to need the Java List class because we are going to create a list of images to create a proton wave that increases in size.
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Assign Variables How do we make the wave grow?
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Add A List (Array) to Store Image Set How many images will this list store?
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Create a Constructer for the Wave The Walker School – Games and Simulations - 2010
Create a Method to Initialize Images The Walker School – Games and Simulations - 2010
Create a Instance Field to Set Image Count
Create a Method to Initialize Images Rewrite the While loop using a For loop. What needs to change?
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Create a Method Stub to Grow Wave The Walker School – Games and Simulations - 2010
Call Method to Grow the Wave The Walker School – Games and Simulations - 2010
Add Statements to Grow Wave Square [] brackets, not curly {} brackets here The Walker School – Games and Simulations - 2010
Add Sound to the Proton Wave The Walker School – Games and Simulations - 2010
Create a Method Stub to Ignite Proton Wave Where do we create this method?
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Call Method When “Z” is Pressed What is the problem with the proton wave?
1. It can be released too easily!
2. It doesn’t do anything to the asteroids!
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Create Reload and Delay for Wave The Walker School – Games and Simulations - 2010
Add an Instance Variable for the Delay Where do we create these variables?
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Assign the Delay to the Constructor The Walker School – Games and Simulations - 2010
Add Delay Count to act() Method The Walker School – Games and Simulations - 2010
Program the Delay into the Wave The Walker School – Games and Simulations - 2010
Interacting with Objects in a Range The Walker School – Games and Simulations - 2010
Program a Method Stub to Check for Collision Purpose is to check to see if the wave touches and asteroid.
So, in what Class do we create this method?
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Call it in the Wave act() Method The Walker School – Games and Simulations - 2010
Write Statements to Check for Collision Range is the radius of the circle (wave).
Why didn’t we use the “getIntersectingObjects() method?
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hit() Method What are the parameters for this method and what does it return?
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Evaluating the Damage Constant What happens when you change the damage constant of the proton wave?
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For Further Development • • • • • • Fix the score counter.
Add new asteroids when all have been cleared.
Add a level counter. Every time all asteroids are destroyed you go up a level.
Add an end of level sound.
Add an indicator showing the load state of the proton wave.
Add a shield.
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