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.Circle;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class PhysDemo extends Application {
    AnimationTimer aTimer;
    Pane physPane;
    Circle ball;
    double ballX,ballY, ballVx, ballVy, ballAy, ballSize;
    double physW = 1000;
    double physH = 600;

    @Override
    public void start(Stage primaryStage) throws Exception {
        ballSize = 20;
        ball = new Circle(ballSize, Color.YELLOW);
        physPane = new Pane(ball);

        //set init. phys.
        ballX = physW/2;
        ballY = physH/2;
        ballAy = 1;
        ballVx = 3;
        ballVy = 2;
        updateBallGfx();

        //timer
        setupTimer();
        aTimer.start();


        Rectangle bgRect = new Rectangle(physW,physH,new Color(.2,.2,.2,1));
        StackPane root = new StackPane(bgRect,physPane);
        Scene scene = new Scene(root,physW, physH);

        primaryStage.setScene(scene);
        primaryStage.setResizable(false);
        primaryStage.show();

    }

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

    void setupTimer(){
        aTimer = new AnimationTimer() {
            @Override
            public void handle(long now) {
                ballVy += ballAy;
                ballX += ballVx;
                ballY += ballVy;

                if (ballX >= physW-ballSize || ballX < ballSize) {
                    ballX -= ballVx; // declip: reverse prev. step
                    ballVx = -ballVx; // reflect
                }

                if (ballY >= physH-ballSize || ballY < ballSize) {
                    ballY -= ballVy;
                    ballVy = -1* ballVy;

                }

                updateBallGfx();
            }
        };
    }

    void updateBallGfx(){
        ball.setCenterX(ballX);
        ball.setCenterY(ballY);
    }
}