always write animationLength in one word without the minus (-) and withot linebreak

animationLength is a variable with a value like 10 or 20.

I assume animationLength tells you how many images you have in your animation.

so somewhere you have a line like

1. int animationLength= 20;

or so

thx for replying.

i added *int animationLength= 20* at the very top, but processing tells me *unexpected token: int* :/

so i assume the program showed in the photo i posted doesnt work at all ?

thanks for help :)

Post your entire code

You need setup() and draw()

I fixed it, know i understand, that it wasnt a whole code...

thank you for your help :)

may i ask if you could help me with another code ?

it looks like this:
void setup() {
  size(600,600);
  smooth();
  noStroke();
  fill (255);
  p = new Partikel();
  p.x = random(width);
  p.y = random(height);
  p.vx = random (-3,3);
  p.vy = random (-3,3);
 
  p2 = new Partikel ();
  p2.x = random(width);
  p2.y = random(height);
  p2.vx = random (-3,3);
  p2.vy = random (-3,3);
}
 
  void draw() {
    background (0);
    p.zeichen();
    p2.zeichnen();
  }
 
  class Partikel {
    float x = 0;
    float y = 0;
    float vx = 1;
    float vy = 1;
  }
 
  void zeichnen () {
    x = x + vx;
    y = y + vy;
   
    if ( x < 0 || x> width ) {
      vx = vx * -1;
    }
    if ( y < 0 || y > heigth ) {
      vy = vy * -1;
    }
    ellipse (x, y, 20, 20);
  }
 

but processing says: *cannot find anything named "p" after hitting the run button :/

i know that i have to initialize new variables at the top of the code, but im not able to figure it out...

i hope you can help

big thanks

Particle p = new Particle(); // or (....) ?
And for p2 too

so where exactly i have to add Particle p = new Particle();   ?
if i just put *Particle* in front of the p, processing says: cannot find a class or type named "particle"....

right in front of the whole code:

Partikel p=new Partikel;

and p2

(I misspelled it)

Before using a class, you have to declare a variable as its type.
Your sketch have a class called Partikel , and you're trying to use a variable called p as such.
However, you haven't declared p as type Partikel anywhere!

Another catch is that for a variable to be accessed everywhere, that is, within any function
like setup() , draw() , mousePressed() , etc.
It has to be declared outside of any function, that is, in a global field.
Preferably, for an easy spot, in the beginning of your sketch, just before void setup() {...}.

Here's a more elaborate tweak of your sketch. Enjoy:
P.S.: In my version, p is called particles! And p itself is just an iterator now!!!

/*
 * Partikel (v2.1)
 * by BreezeHawk (2013/Jan)
 *
 * http://forum.processing.org/topic/
 * help-with-certain-problem-moving-and-morphing-circle
 */

final static byte numParticles = 10;
final static Partikel[] particles  = new Partikel[numParticles];

void setup() {
    size(600, 600);
    frameRate(50);
    ellipseMode(CENTER);
    smooth();
    noStroke();

    for ( byte p=0; p!=numParticles;
    particles[p++] = new Partikel(10, 7, 30, 20, #00FFFF) );
}

void draw() {
    background (0);

    for (Partikel p: particles)    p.zeichnen();
}

class Partikel {
    int w = 20, h = 20;
    int ww = w>>1, hh = h>>1;
    int vx = 1, vy = 1;
    color c = 255;

    int x = (int) random(w, width-w);
    int y = (int) random(h, height-h);

    Partikel() {
    }

    Partikel(int spd) {
        vx = vy = (int) random(1, spd+1) * (random(2)<1 ? -1 : 1);
    }

    Partikel(int spdX, int spdY) {
        this(spdX, spdY, 255);
    }

    Partikel(int spdX, int spdY, color col) {
        this(spdX, spdY, 20, 20, col);
    }

    Partikel(int spdX, int spdY, int sizeX, int sizeY) {
        this(spdX, spdY, sizeX, sizeY, 255);
    }

    Partikel(int spdX, int spdY, int sizeX, int sizeY, color col) {
        vx = (int) random(1, spdX+1) * (random(2)<1 ? -1 : 1);
        vy = (int) random(1, spdY+1) * (random(2)<1 ? -1 : 1);
        w  = sizeX;
        h  = sizeY;
        ww = w>>1;
        hh = h>>1;
        c  = col;
    }

    void zeichnen() {
        if ( (x += vx) < ww || x > width-ww )     vx *= -1;
        if ( (y += vy) < hh || y > height-hh )    vy *= -1;

        fill(c);
        ellipse (x, y, w, h);
    }
}

Nice, thanks to both of you guys :)