Java Defenderz Game

Open a new Processing sketch, paste in the code below and save it as Defenderz. On moodle you will find a background gif file. Download the file to your Defenderz directory. The code below will give you a horiztonal scrolling background image which wraps around.

PImage background;
int x=0; //global variable background location

void setup() {
size(800, 400);
background = loadImage("spaceBackground.jpg");
background.resize(width,height);
}

void draw() {
image(background, x, 0); //draw background twice adjacent
image(background, x+background.width, 0);
x -= 4;
if(x == -background.width)
x=0; //wrap around
}

Defenderz Game

1st prototype has

• alien (moving left, and perhaps up and down).
  • color ALIEN1 = color(0, 255, 0);
  • color ALIEN2 = color(50, 100, 0);
• A defender
  • Moved up and down by player
  • Can crash into alien
  • Detect by alien colour (area just in front of the defender)
  • color ALIEN1 = color(0, 255, 0);
  • color ALIEN2 = color(50, 100, 0);

What Classes do we require?

What constructors & methods for each?

Add the defender class (do not use the same name as the sketch! - nested class error)

//draw a defender
fill(255, 0, 0);
rect(x, y, 50, 20);
triangle(x+50, y, x+50, y+20, x+60, y+10);
fill(0, 0, 100);
rect(x, y-10, 20, 10);

Add a defender instance with user interaction (key press move up and down) and test it

Add an Alien class

//draw an alien
fill(ALIEN1);
ellipse(x, y, 30, 20);
fill(ALIEN2);
ellipse(x, y, 50, 15);

Add an instance of an Alien and test it

Add a crash Boolean method to Defender. We could use a distance measure as we have previously (asserting that a crash has taken place if the two objects are within a certain distance) but here we'll use a different technique instead.

A crash has taken place if we detect the alien's colours just in front of the defender ship. To do this we need to check a range of pixels (e.g. yellow are in image) and test whether ALIEN1 colour or ALIEN2 colour is present - how?

FOR LOOP - repeat a block of actions a set number of times
color test = get(x, y);

FOR LOOP - repeat a block of actions a set number of times
color test = get(x, y);
will get the colour of the pixel at x,y, what value should x be - the defender is 60 pixels wide, so defender's x + 65 would be just in front.

if(test == ALIEN1)
Ensure you have drawn the alien on the screen (in draw event) before checking for a crash!!

Complete the 1st prototype of the game
Add 3 aliens (2 more)
Use a gameMode variable to stop the game if a crash occurs
Allow the alien to move up or down in some sequence (as well as left)
If the alien goes off the screen a new alien should appear on the right