CMSC 110 (Introduction to Computing)

Spring 2011

Assignment#5

Due before start of class on Thursday, March 24, 2011

Task: Design an underwater creature. The creature should be designed so that it can be instantiated as an object. Make sure you name the class as <YourFirstInitialLastName>Obj. For example Eric's creature will be defined in a class called EEatonObj. You should be able to create instances of the creature with varying sizes through a single float passed into the constructor. In addition to the constructor, make sure that the class includes methods called display(), move(), getX(), and getY().  Your implementation should look like the following:

class <First Initial Last Name>Obj extends AnimatedObject { // keep this line as is, except for renaming the class

   /** Constructor */
   <First Initial Last Name>Obj(float size) { ... }

   void display() { ... }

   void move() { ... }

   int getX() { ... }

   int getY() { ... }
}



/** If you want to enhance the tank background
* to showcase your own project, you can put
* drawing code in this function, which is called
* near the start of the draw() function below.
*/
void drawTankBackground() { }

/***************************************
 DO NOT MODIFY FROM HERE ...
****************************************/
 
/** The array of objects */
AnimatedObject[] objs = new AnimatedObject[5];

/** Constant for the sandHeight */
int SAND_HEIGHT = 40;


/** Setup the sketch */
void setup() {
  size(800,600);
  smooth();
  // initialize all the objects
  for (int i=0; i < objs.length; i++) {
    objs[i] = new EEatonObj(random(30,50));   // the one change you'll need to make is changing this line to call your constructor
  }
}


/** The main draw loop */
void draw() {
  
  // draw the tank background
  background(50,50,255);
  
  // draw the sandy bottom of the tank
  fill(168,168,50);
  rect(0,height-SAND_HEIGHT, width, SAND_HEIGHT);
  
  // draw the enhanced tank background, if necessary
  drawTankBackground();
  
  // create the vector of all object's locations
  PVector[] allObjectsLocations = new PVector[objs.length];
  for (int i=0; i<objs.length; i++) {
    allObjectsLocations[i] = new PVector(objs[i].getX(), objs[i].getY());
  }
  
  // draw and animate each of the objects
  for (int i=0; i<objs.length; i++) {
    objs[i].display();
    objs[i].move(allObjectsLocations);
  }
}



/** An abstract class for animated objects */
abstract class AnimatedObject {
  
  /** Constructor
   *  Note that your constructor should accept a single float specifying the size
   */
  
  /** Displays the object */
  abstract void display();
  
  /** Advances the object's animation by one frame 
   *  Note: Implement only one of the move() functions, but NOT both.
   */
  void move() { }
  
  /** Advances the object's animation by one frame.
   *  Note: Implement only one of the move() functions, but NOT both.
   *  @param allObjectsLocations an array of the locations of ALL objects in the environment
   */
  void move(PVector[] allObjectsLocations) { move(); }
  
  /** Getter for the object's x position 
   *  @return the object's x position (as measured from the center of the object)
   */
  abstract int getX();
  
  /** Getter for the object's y position 
   *  @return the object's y position (as measured from the center of the object)
   */
  abstract int getY();
}


/**************************************
 ... TO HERE
***************************************/

Hints:

• Keep it simple at first.  Start with something basic, get it working, and then build upon it piece by piece, each time ensuring it is working before you move on to the next piece.
• Start with a hand-drawing of what you want, preferrably on graph paper.
• START EARLY!!!  I cannot emphasize this enough.

Extra Credit:

For up to 20 points extra credit, you can make your object react to nearby objects in the aquarium.  Instead of using the move() function defined above, use the following in its place:

/** Advances the object's animation by one frame.
 *  Note: Implement only one of the move() functions, but NOT both.
 *  @param allObjectsLocations an array of the locations of ALL objects in the environment
 */
void move(PVector[] allObjectsLocations) { ... }