Java ball motion: unexpected behavior of boundary reflection

php editor Xigua introduces you to the Java Q&A series. This issue discusses the unexpected behavior of boundary reflection in Java ball movement. During the programming process, we often face various unexpected situations, especially problems involving physical simulation that are more complex. This article will analyze for you the unexpected behavior that may occur during boundary reflection in Java ball movement, help you better understand and deal with such problems, and improve your programming skills.

Question content

`Question:

I am developing a java program in which I simulate the movement of a ball inside a box. Use the vector reflection formula to expect the ball to reflect from the boundaries of the box. However, I encountered unexpected behavior, the ball not only went out of bounds, but also changed position strangely.

Problem Description:

I implemented the motion of the ball using basic straight line equations (x=x0 at, y=y0 bt, z=z0 ct). I suspect the problem lies with the part of the code responsible for detecting collisions and updating the ball's path. `

import java.util.Scanner;
import java.lang.Math;

public class test {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Get initial positions for ball 1
        System.out.print("Enter ball 1's initial x-coordinate (x): ");
        double x1 = scanner.nextDouble();
        System.out.print("Enter ball 1's initial y-coordinate (y): ");
        double y1 = scanner.nextDouble();
        System.out.print("Enter ball 1's initial z-coordinate (z): ");
        double z1 = scanner.nextDouble();
        System.out.print("Enter ball 1's radius(r): ");
        double r1 = scanner.nextDouble();

        // Get direction vectorfor ball 1
        System.out.print("Enter direction in x-coordinate (a): ");
        double a = scanner.nextDouble();
        System.out.print("Enter direction in y-coordinate (b): ");
        double b = scanner.nextDouble();
        System.out.print("Enter direction in z-coordinate (c): ");
        double c = scanner.nextDouble();



        double rt = 0;
        double t1 = 0;
        double t2 = 0;
        while(true) {
            double X1 = x1 + a * t1;
            double Y1 = y1 + b * t1;
            double Z1 = z1 + c * t1;

//**collision**

//This is the part that detects the collision and makes a new path for the ball
            
            if (X1-r1 < -25){
                a = -a;
                x1 = -x1;
                System.out.printf("ball hit\n");

            }
            else if (X1+r1 > 25){
                a = -a;
                x1 = -x1;
                System.out.printf("ball hit\n");
                System.out.printf("%f%f%f\n", a, b, c);
            }
            else if (Y1-r1 < -25){
                b = -b;
                y1 = -y1;
                System.out.printf("ball hit\n");
                System.out.printf("%f%f%f\n", a, b, c);
            }
            else if (Y1+r1 > 25){
                b = -b;
                y1 = -y1;
                System.out.printf("ball hit\n");
                System.out.printf("%f%f%f\n", a, b, c);
            }
            else if (Z1-r1 < -25){
                c = -c;
                z1 = -z1;
                System.out.printf("ball hit\n");
                System.out.printf("%f%f%f\n", a, b, c);
            }
            else if (Z1+r1 > 25){
                c = -c;
                z1 = -z1;
                System.out.printf("ball hit\n");
                System.out.printf("%f%f%f\n", a, b, c);
            }
            else{
                System.out.printf("ball in boundary\n");
            }


            System.out.printf("Ball 1 at t=%.2f seconds: (%.2f, %.2f, %.2f)%n", rt, X1, Y1, Z1);

            rt += 1;
            t1 += s1;
            // t2 += s2;
            if (rt>10){
                break;
            }
        }

        // Close the scanner
        scanner.close();
    }


}

Expected Behavior:

I want the ball to properly reflect off the boundary and stay inside the box.

Observed Behavior:

However, the ball went out of bounds and unexpectedly changed position.

question:

Could you please go over the collision detection and reflection portions of my code and suggest any corrections? Is there a more efficient way to handle ball reflections outside the inner bounds of the box? Additional Information:

java programming language Calculate the motion of a ball using the basic equations of a straight line Vector reflection formula for collision handling`

Solution

I think I fixed the code here is the fixed code

import java.util.Scanner;
import java.lang.Math;

public class BallExample{

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    // Get initial positions for ball 1
    System.out.print("Enter ball 1's initial x-coordinate (x): ");
    double x1 = scanner.nextDouble();
    System.out.print("Enter ball 1's initial y-coordinate (y): ");
    double y1 = scanner.nextDouble();
    System.out.print("Enter ball 1's initial z-coordinate (z): ");
    double z1 = scanner.nextDouble();
    System.out.print("Enter ball 1's radius(r): ");
    double r1 = scanner.nextDouble();

    // Get direction vectorfor ball 1
    System.out.print("Enter direction in x-coordinate (a): ");
    double a = scanner.nextDouble();
    System.out.print("Enter direction in y-coordinate (b): ");
    double b = scanner.nextDouble();
    System.out.print("Enter direction in z-coordinate (c): ");
    double c = scanner.nextDouble();



    // Get speed
    System.out.print("Enter speed for ball 1(units per second): ");
    double s1 = scanner.nextDouble();





    double rt = 0;
    double t1 = 0;
    while(true) {
        double X1 = x1 + a * t1;
        double Y1 = y1 + b * t1;
        double Z1 = z1 + c * t1;


        System.out.printf("Ball 1 at t=%.2f seconds: (%.2f, %.2f, %.2f)%n", rt, X1, Y1, Z1);

        if (X1+r1>=25||X1-r1<=-25){
            a=-a;
            System.out.printf("HIT\n");
            
        }
        
        
        if (Y1+r1>=25||Y1-r1<=-25){
            b=-b;
            System.out.printf("HIT\n");
            
        }
        
        
        if (Z1+r1>=25||Z1-r1<=-25){
            c=-c;
            System.out.printf("HIT\n");
            
        }

        x1=X1;
        y1=Y1;
        z1=Z1;

        t1 = s1;
        rt += 1;
        if(rt>10){
            break;
        }

    // Close the scanner
    scanner.close();
   }
}}

The above is the detailed content of Java ball motion: unexpected behavior of boundary reflection. For more information, please follow other related articles on the PHP Chinese website!