Question

Write function to check if point O is located inside or outside of the 2D triangle ABC The coordinates of the vertices are defined inside Coordinates.dat file. Read this file inside main m-file and provide the coordinates as an input to the function. Also ask user to input coordinates of the point O and provide it as input to the function as well. The output of the function should be a message, saying that the point is located inside or outside of the triangle. Hint: point O split ABC into small triangles

Answer 1

package abcSolution1;

public class Triangle2D {

MyPoint p1;

MyPoint p2;

MyPoint p3;

public MyPoint getP1()

{

return p1;

}

public void setP1(MyPoint p1)

{

this.p1 = p1;

}

public MyPoint getP2()

{

return p2;

}

public void setP2(MyPoint p1)

{

this.p2 = p2;

}

public MyPoint getP3()

{

return p3;

}

public void setP3(MyPoint p3)

{

this.p3 = p3;

}

Triangle2D()

{

p1 = new MyPoint(0,0);

p2 = new MyPoint(1,1);

p3 = new MyPoint(2,5);

}

Triangle2D(MyPoint p1, MyPoint p2, MyPoint p3)

{

this.p1 = p1;

this.p2 = p2;

this.p3 = p3;

}

public double getArea(){

double side1 = Math.sqrt(Math.pow(p2.getX()

-p1.getX(),2)+Math.pow(p2.getY()-p1.getY(),2));

double side2 = Math.sqrt(Math.pow(p3.getX()

-p2.getX(),2)+Math.pow(p3.getY()-p2.getY(),2));

double side3 = Math.sqrt(Math.pow(p1.getX()

-p3.getX(),2)+Math.pow(p1.getY()-p3.getY(),2));

double s =(side1 + side2 + side3)/2;

double area = Math.sqrt(s * ((s - side1) * (s - side2) * (s - side3)));

return area;

}

public double getArea(MyPoint p1, MyPoint p2, MyPoint p3){

double side1 = Math.sqrt(Math.pow(p2.getX()

-p1.getX(),2)+Math.pow(p2.getY()-p1.getY(),2));

double side2 = Math.sqrt(Math.pow(p3.getX()

-p2.getX(),2)+Math.pow(p3.getY()-p2.getY(),2));

double side3 = Math.sqrt(Math.pow(p1.getX()

-p3.getX(),2)+Math.pow(p1.getY()-p3.getY(),2));

double s =(side1 + side2 + side3)/2.0;

double area = Math.sqrt(s * ((s - side1) * (s - side2) * (s - side3)));

return area;

}

public boolean contains(MyPoint p){

// if point p is inside traingle ABC then

// area of pab+pbc+pca should equal to area of abc

if(Math.round(getArea(p, p1, p2)+getArea(p, p2, p3)+getArea(p, p3, p1))==Math.round(getArea(p1, p2, p3)))

return true;

return false;

}

}

package abcSolution1;

public class MyPoint {

double x;

double y;

public MyPoint(double x, double y) {

super();

this.x = x;

this.y = y;

}

public MyPoint() {

// TODO Auto-generated constructor stub

}

public double getX() {

return x;

}

public void setX(double x) {

this.x = x;

}

public double getY() {

return y;

}

public void setY(double y) {

this.y = y;

}

public double distance(MyPoint point) {

return Math.sqrt(Math.pow(point.getX()-this.getX(),2)+Math.pow(point.getY()-this.getY(),2));

}

}

package abcSolution1;

import java.io.File;

import java.io.FileNotFoundException;

import java.util.Scanner;

public class TriangleDriver {

public static void main(String[] args) {

File file = new File("Coordinates.dat");

try {

Scanner sc=new Scanner(file);

String line1=sc.nextLine();

String line2=sc.nextLine();

String line3=sc.nextLine();

MyPoint point1=new MyPoint(Double.valueOf(line1.split(" ")[0]), Double.valueOf(line1.split(" ")[1]));

MyPoint point2=new MyPoint(Double.valueOf(line1.split(" ")[0]), Double.valueOf(line1.split(" ")[1]));

MyPoint point3=new MyPoint(Double.valueOf(line1.split(" ")[0]), Double.valueOf(line1.split(" ")[1]));

sc=new Scanner(System.in);

System.out.println("Enter x coordinate of point o");

double x=sc.nextDouble();

System.out.println("Enter y coordinate of point o");

double y=sc.nextDouble();

MyPoint o=new MyPoint(x, y);

Triangle2D triangle = new Triangle2D(point1, point2, point3);

System.out.println(triangle.contains(o));

} catch (FileNotFoundException e) {

e.printStackTrace();

}

}

}