BLA algorithm Computer Graphics

BLA13.java

package hw;
import java.lang.Math;
import java.applet.Applet;
import java.awt.Graphics;
import java.util.Scanner;

public class BLA13 extends Applet {
	int x1, x2, y1, y2;
	int a, b;
	double Steps;
	double dx, dy;
	double xINC, yINC;
	int x, y;
	long p;

	public void paint(Graphics g) {
		Scanner input = new Scanner(System.in);
		System.out.println("Enter x1,y1,x2 and y2 coordinates: ");

		x1 = input.nextInt();
		y1 = input.nextInt();
		x2 = input.nextInt();
		y2 = input.nextInt();

		if (x2 > x1){
			a = 1;
		} else {
			a = -1;
		}
		if (y2 > y1){
			b = 1;
		} else {
			b = -1;
		}
		
		dx = Math.abs(x2 - x1);
		dy = Math.abs(y2 - y1);
		x = x1;
		y = y1;
		if (dx > dy) {
			p = Math.round((2 * dy - dx));
			for (int i = 0; i < dx; i++) {
				g.fillOval(x, y, 5, 5);
				if (p <= 0) {
					x = x + a;
					y = y;
					p = (int) (p + 2 * dy);
				} else {
					x = x + a;
					y = y + b;
					p = (int) (p + 2 * dy - 2 * dx);
				}
			}
		} else {
			p = Math.round((2 * dx - dy));
			for (int i = 0; i < dy; i++) {
				g.fillOval(x, y, 5, 5);
				if (p <= 0) {
					x = x;
					y = y + b;
					p = (int) (p + 2 * dx);
				} else {
					x = x + a;
					y = y + b;
					p = (int) (p + 2 * dx - 2 * dy);
				}
			}
		}
	}
}