COS126

• Download Diamond.java

/******************************************************************************
  * Name: Donna Gabai
  * NetID: dgabai
  * Precept: P99
  * 
  * Description: An object class to represent a 2D diamond.
  * 
  * Dependencies: StdDraw
  ****************************************************************************/

import java.awt.Color;

public class Diamond {
    
    // instance variables
    private final double r;    // center to vertex distance
    private double x;          // center x-coordinate
    private double y;          // center y-coordinate
    private Color c;           // color of the diamond
    
    // constructor (does not draw the diamond)
    public Diamond(double r, double x, double y, Color c) {
        
        // put the values of the arguments into the instance variables
        this.r = r;
        this.x = x;
        this.y = y;
        this.c = c;
    }
    
    // sets the pen color and draws the diamond
    public void drawFilled() {
        
        // compute the vertices and pack into x and y arrays
        double[] xPts = {x - r, x, x + r, x};
        double[] yPts = {y, y + r, y, y - r};
        
        // set pen color
        StdDraw.setPenColor(c);
        
        // draw
        StdDraw.filledPolygon(xPts, yPts);
    }
    
    // returns the area of the diamond: area = 2 * (r squared)
    public double area() {
        double a = 2 * r * r;
        return a;
    }
    
    // changes the color
    public void changeColor(Color newColor) {
        c = newColor;
    }
    
    // changes the position
    public void move(double deltax, double deltay) {
        x = x + deltax;
        y = y + deltay;
    }
    
    // test main (provided)
    public static void main(String[] args) {
        StdDraw.setXscale(-1, 1); // set scale
        StdDraw.setYscale(-1, 1); // in main()
        Color red = StdDraw.RED;
        Diamond d = new Diamond(.5, -.5, .5, red);
        d.drawFilled();
        System.out.println(d.area());
        d.changeColor(StdDraw.BLUE);
        d.move(1, -1);
        d.drawFilled();
        System.out.println(d.area());
    }
}