Why one of the balls does not move?

zheng

float x [] = {10, 20, 30};
float xs [] = {2, 3, 5};
float y [] = {10, 20, 30};
float ys [] = {2, 3, 5};

void setup() {
  size(500, 500);
}
void draw() {
  background(0);
  for (int i = 0; i< 3; i++) {
    ellipse(x[i], y[i], 30, 30);
    x[i]= x[i]+xs[i];
    y[i]= y [i]+ys[i];


    if ((x[i]>width-15)||(x[i]<15)) {
      xs[i] = -xs[i];
    }

    if ((y[i]>height-15)||(y[i]<15)) {
      ys[i] = -ys[i];
    }
  }
}

Chrisir

it stutters in the return zone because of * -1

better to use abs() and -abs() separately:

float x [] = {10, 20, 30}; 
float xs [] = {2.3, 3.3, 5.2}; 
float y [] = {10, 20, 30}; 
float ys [] = {2.01, -3, 5.7};

void setup() { 
  size(500, 500);
} 
void draw() { 
  background(0); 
  for (int i = 0; i< 3; i++) { 
    ellipse(x[i], y[i], 30, 30); 
    x[i]= x[i]+xs[i]; 
    y[i]= y [i]+ys[i];

    if ((x[i]>width-15)) {
      xs[i] = -abs(xs[i]);
    }

    if (x[i]<15) {
      xs[i] = abs(xs[i]);
    }

    if ((y[i]>height-15)) {
      ys[i] = -abs(ys[i]);
    }


    if (y[i]<15) {
      ys[i] = abs(ys[i]);
    }
  }
} 

Chrisir

https://forum.processing.org/two/discussion/17486/puzzle-ball-in-a-box-why-does-the-rebound-fail#latest

koogs

use ctrl-o to indent code when posting to the forum.

if ((x[i]>width-15)||(x[i]<15)) {

you wouldn't write a sentence without spaces, so why write codeallsquashedtogetherlikethis?

if ((x[i] > width - 15) || (x[i] < 15)) {

so much more readable