package ceccs;

import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;

public class PhysBall extends Circle {
    PhysDemoScaleUp app;
    private double x, y, vx, vy, ax, ay, radius;
    static double gravity = 1;

    PhysBall(double ballSize, Color color, double x, double y, PhysDemoScaleUp app){
        super(x,y,ballSize,color);
        this.app = app;
        radius = ballSize;
        this.x = x;
        this.y = y;
        vx = 0;
        vy = 0;
        ax = 0;
        ay = 0;
        app.physPane.getChildren().add(this);
    }

    void updatePhysics(){
        vx += ax;
        x += vx;
        vy += ay;
        y += vy;

        //collision with sides
        if (x < 0 || x > app.physW) {
            x -= vx; // take away the last step
            vx = -vx; // reflect x velocity
        }
        if (y < 0 || y > app.physH) {
            y -= vy; // take away the last step
            vy = -vy; // reflect x velocity
        }
    }

    void updateGraphics(){
        setCenterX(x);
        setCenterY(y);
    }

    void setVelocity(double vx, double vy){
        this.vx = vx;
        this.vy = vy;
    }

    void enableGravity(){
        this.ay = gravity;
    }
}

package ceccs;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

import java.util.ArrayList;
import java.util.Random;

public class PhysDemoScaleUp extends Application {

    AnimationTimer timer;
    Pane physPane;
    double physW = 1000;
    double physH = 600;
    Stage stage;
    ArrayList<PhysBall> balls;


    public static void main(String[] args){
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        stage = primaryStage;
        setupLayout();

        balls = new ArrayList();
        //Random randy = new Random();
        for(int i = 0; i < 1000; i++){
            double rx = Math.random()*physW;
            double ry = Math.random()*physH;
            PhysBall b = new PhysBall(5, new Color( 0, Math.random(),Math.random(), .35 ), rx,ry, this );
            b.setVelocity(Math.random()-.5, Math.random()-.5);
            b.enableGravity();
            balls.add(b);
        }
        setupTimer();
        timer.start();

        primaryStage.setTitle("Physics-ScaleUp-Tester");
        primaryStage.show();
    }

    void setupLayout(){
        Rectangle bgRect = new Rectangle(physW,physH,new Color(.2,.2,.2,1));
        physPane = new Pane();
        StackPane root = new StackPane(bgRect, physPane);
        Scene scene = new Scene(root);
        stage.setScene(scene);
        stage.setResizable(false);
    }

    void setupTimer(){
        timer = new AnimationTimer() {
            @Override
            public void handle(long now) {
                for(int i = 0; i < balls.size(); i++){
                    balls.get(i).updatePhysics();
                    balls.get(i).updateGraphics();
                }
            }
        };
    }
}