Objects-Late and Objects-Early Comparison

Below is a comparison between an objects-late and objects-early version of the Angry Bird App. The main difference is that in the objects-late version the students will need to implement two standard methods for: Students familiar with classes/objects could use the available methods distance(Shape s1, Shape s2) and contains(Point p).

Objects-LateObjects-Early
package edu.compsci;

import cs1.android.*;

// Fling the bird so that it flies on top of the pig.

public class AngryBirdApp extends AndroidApp
{
	// for 320x480 screen in landscape mode
	final int WIDTH = 480;
	final int HEIGHT = 320;

	// distance considered a hit
	final double HIT_DIST = 5.0;

	// computes the distance between the given points
	public double distance(double x1, double y1, double x2, double y2)
	{
		double dx = x1 - x2;
		double dy = y1 - y2;
		return Math.sqrt(dx*dx + dy*dy);
	}

	// check if the bird is visible
	public boolean isVisible(double birdX, double birdY)
	{
		if (birdX > 0 && birdX < WIDTH && birdY > 0 && birdY < HEIGHT) {
			return true;
		}
		else {
			return false;
		}
	}

	public void run() 
	{	
		// position pig and bird at opposite corners
		double birdX = 60, birdY = 60;
		double pigX = 420, pigY = 260;

		// draw the scene
		canvas.drawImage(240,  169, "background.png");
		canvas.drawImage(pigX, pigY, "pig.png");
		canvas.drawImage(birdX, birdY, "bird.png");





		// get the fling direction
		Fling fling = canvas.waitForFling();
		double dx =  fling.getDx();
		double dy =  fling.getDy();

		// use the speed to update position as long as bird in view and away from pig
		double speedX = 3, speedY = 6;
		while (distance(birdX, birdY, pigX, pigY) > HIT_DIST && isVisible(birdX, birdY)) {
			birdX = birdX + speedX*dx;
			birdY = birdY + speedY*dy;

			canvas.sleep(.01);

			// redraw the scene
			canvas.clear();
			canvas.drawImage(240,  169, "background.png");
			canvas.drawImage(pigX, pigY, "pig.png");
			canvas.drawImage(birdX, birdY, "bird.png");
		}	
	}
}

package edu.compsci;

import cs1.android.*;

// Fling the bird so that it flies on top of the pig.

public class AngryBirdObjectsApp extends AndroidApp
{
	// for 320x480 screen in landscape mode
	final int WIDTH = 480;
	final int HEIGHT = 320;

	// distance considered a hit
	final double HIT_DIST = 40.0;








	// Use the methods distance(Shape s1, Shape s2) and contains(Point p)
	// see the while loop	










	public void run() 
	{	
		// position pig and bird at opposite corners
		double birdX = 60, birdY = 60;
		double pigX = 420, pigY = 260;

		// draw the scene
		Shape field = new Image(240,  169, "background.png");
		Shape pig = new Image(pigX, pigY, "pig.png");
		Shape bird = new Image(birdX, birdY, "bird.png");

		field.draw();
		pig.draw();
		bird.draw();

		// get the fling direction
		Fling fling = canvas.waitForFling();
		double dx =  fling.getDx();
		double dy =  fling.getDy();

		// use the speed to update position as long as bird in view and away from pig
		double speedX = 3, speedY = 6;
		while (Shape.distance(bird, pig) > HIT_DIST &&  field.contains(bird.getCenter())) {
			bird.move(speedX*dx, speedY*dy);			
			canvas.sleep(.01);
		}	
	}
}