Crafts/ Calvao CSC-220 PolyHW

/*
 * Name: Philip Crafts/ Luis Calvao
 * Date: 9/22/17
 * Course Number: CSC 220
 * Course Name: Data Structures and Algorithims
 * Problem Number: N/A
 * Email: prcrafts@student.stcc.edu / lccalvao@student.stcc.edu
 * Returns the area of a convex polygon from points entered clockwise
 */

import java.util.Scanner;


public class polygonHW {


    private static void process(Scanner sc, String args[])  {
        // Code here is merely a sample
        int size = 0;

        while(size < 3)
        {
        System.out.print("Enter number of points (must be more than 3)");
        size = sc.nextInt();
        }

        Double[] x = new Double[size];
        Double[] y = new Double[size];

        System.out.println("Enter points in Rectangular form (seperated by spaces not commas)");
        getPoints(sc, x,y);
        printPoints(x,y);
        printArea(x,y);

        sc.nextLine();
    }

     private static boolean doThisAgain(Scanner sc, String prompt) {
            System.out.print(prompt);
            String doOver = sc.nextLine();
            return doOver.equalsIgnoreCase("Y");
        }

     public static void main(String args[]) {
            final String TITLE = "Crafts/Calvao polygonHW";
            final String CONTINUE_PROMPT = "Do this again? [y/N] ";

            System.out.println("Welcome to " + TITLE);
            Scanner sc = new Scanner(System.in);
            do {
                process(sc, args);
            } while (doThisAgain(sc, CONTINUE_PROMPT));
            sc.close();
            System.out.println("Thank you for using " + TITLE);
        }


    private static void printArea(Double[] x, Double[] y) {

        double theta = 0;
        double hyp = 0;
        double base = 0;
        double height = 0;
        double Area = 0;
        double heronCheck = 0;

        x = orientArr(x);
        y = orientArr(y);

        for(int i = 1; i < x.length -1 ; i++ )
        {
            base = simpleDist(x[i] , y[i]);
            hyp = simpleDist(x[i+1] , y[i+1]);

            theta = Math.atan2(y[i], x[i]) - Math.atan2(y[i+1], x[i+1]);

            height = Math.sin(theta) * hyp;

            heronCheck = (base * height)/2;

            if(heronCheck <= 0)
            {
                System.out.println("not a convex polygon");
                return;
            }

            Area += heronCheck;
        }

        System.out.printf("Area = %.2f\n", Area);
        //System.out.print("\n");
    }




    //sets points stored at [0] as origin
    private static Double[] orientArr(Double[] x) {

        double xCancel = x[0];

        for(int i = 0; i < x.length ; i++ )
        {
            x[i] -= xCancel;
        }

        return x;
    }


    private static double simpleDist(Double x, Double y) {

    return  Math.sqrt(Math.pow(x,2d) + Math.pow(y,2));

    }

    private static void printPoints(Double[] x, Double[] y) {
        System.out.println("Collected Points");
        for(int i = 0; i < x.length ; i++ ) {
            System.out.println(x[i] +" , " +  y[i]);
        }

    }

    private static void getPoints(Scanner sc, Double[] x, Double[] y) {

        int hold;

        for(int i = 0; i < x.length ; i++ ) {
            hold = i+1;
            System.out.println("point " + hold + ": ");
            x[i] = sc.nextDouble();
            y[i] = sc.nextDouble();
        }


    }


}