package Geometria;
public class Reta {
	private Ponto p1,p2;
	
	public Reta(double x1,double y1,double x2,double y2) {
		p1 = new Ponto(x1,y1);
		p2 = new Ponto(x2,y2);
	}

	public Ponto getP1() { return p1; }
  public Ponto getP2() { return p2; }	

	public static double f(Reta r, double x) {
		// retorno eŽ y em funcao fr de x
		// (Y - y1) / (y2-y1) = (X - x1)/(x2 - x1)
		return ( r.getP1().getY() +
			      ( ( (r.getP2().getY()-r.getP1().getY()) * (x - r.getP1().getX())  ) /
			        (r.getP2().getX()-r.getP1().getX())  )  );
	}
	
	private static double coefLin(Reta r) {
		// coeficiente linear: onde esta y quando x eŽ0
		// na forma: y + CoefAng x + CoefLin = 0
		return f(r,0);
	}
	
	private static double coefAng(Reta r) {
		// y = x . &  onde & = (y2-y1) / (x2-x1)
		// na forma: 1.y + CoefAng.x + CoefLin = 0
	  return  ( ( r.getP2().getY() - r.getP1().getY() ) / 
	  	        ( r.getP2().getX() - r.getP1().getX() ) );
	}
		
	private static double D(Reta r1, Reta r2) {
	  return ( coefAng(r2) - coefAng(r1) );
	}
	
	private static double Dx(Reta r1, Reta r2) {
	  return ( ( coefLin(r1)*coefAng(r2) ) - ( coefLin(r2)*coefAng(r1) ) );	
	}
	
	private static double Dy(Reta r1, Reta r2) {
		// sempre 1.y
	  return ( coefLin(r1) - coefLin(r2) );	
	}

	public static Ponto intercessao (Reta r1, Reta r2) {
		return new Ponto((Dx(r1,r2)/D(r1,r2)), (Dy(r1,r2)/D(r1,r2)));		
	}
	

  public void info() { 
  	System.out.println(" Reta com P1 e P2: ");
  	p1.info();
  	p2.info();
  	System.out.println("Coef.Lin: "+coefLin(this));
		System.out.println("Coef.Ang: "+coefAng(this));

  }
		
}