gann-cdf / graphics

import org.gannacademy.cdf.graphics.geom.Ellipse;

import org.gannacademy.cdf.graphics.ui.DrawingPanel;

import java.awt.*;

public class Bubble {

    private Ellipse e;

    private double dx, dy;

    public static final double DEFAULT_RADIUS = 10;

    public Bubble(DrawingPanel p) {

        if (Math.random() > 0.5) {

            e = new Ellipse((Math.random() > 0.5 ? -DEFAULT_RADIUS : p.getWidth()), Math.random() * p.getHeight(), DEFAULT_RADIUS, DEFAULT_RADIUS, p);

        } else {

            e = new Ellipse(Math.random() * p.getWidth(), (Math.random() > 0.5 ? -DEFAULT_RADIUS : p.getHeight()), DEFAULT_RADIUS, DEFAULT_RADIUS, p);

        }

        e.setFillColor(new Color((float) Math.random(), (float) Math.random(), (float) Math.random(), 1));

        e.setStrokeColor(e.getFillColor().darker());

        dx = Math.random() * (DEFAULT_RADIUS / 2) - (DEFAULT_RADIUS / 4);

        dy = Math.random() * (DEFAULT_RADIUS / 2) - (DEFAULT_RADIUS / 4);

    }

    public void step() {

        e.translate(dx, dy);

        if (e.getX() > e.getDrawingPanel().getWidth() || e.getX() < -e.getWidth()) {

            dx = -1 * dx;

        }

        if (e.getY() > e.getDrawingPanel().getHeight() || e.getY() < -e.getHeight()) {

            dy = -1 * dy;

        }

    }

    public double getRadius() {

        return e.getWidth() / 2;

    }

    public boolean intersects(Bubble other) {

        return Math.hypot(e.getX() - other.e.getX(), e.getY() - other.e.getY()) < getRadius() + other.getRadius();

    }

    public void absorb(Bubble other) {

        double a = Math.PI * (Math.pow(getRadius(), 2) + Math.pow(other.getRadius(), 2)),

                r = Math.sqrt(a / Math.PI),

                dr = (r - getRadius()) / 2,

                ratio = getRadius() / other.getRadius();

        dx = (ratio * dx + other.dx) / ratio;

        dy = (ratio * dy + other.dy) / ratio;

        e.setFillColor(new Color(

                (int) Math.sqrt((Math.pow(e.getFillColor().getRed(), 2) + Math.pow(other.e.getFillColor().getRed(), 2)) / 2),

                (int) Math.sqrt((Math.pow(e.getFillColor().getGreen(), 2) + Math.pow(other.e.getFillColor().getGreen(), 2)) / 2),

                (int) Math.sqrt((Math.pow(e.getFillColor().getBlue(), 2) + Math.pow(other.e.getFillColor().getBlue(), 2)) / 2)

        ));

        e.setStrokeColor(e.getFillColor().darker());

        e.setFrame(e.getX() - dr, e.getY() - dr, r * 2, r * 2);

    }

}