Problem with for loops, i want my grid to move in float values not ints

Programming Questions

GiorgioMa..

Problem with for loops, i want my grid to move in float values not ints

in Programming Questions • 5 months ago

Hi, my sketch here it creates a row of random circles and them moves them downwards :

Its almost all good, but i want the circles to move slowly downwards like this:

Now they jump from one row to the next, i want them to slide slowly down... but i cant figure how to ... i guess i should use floats instead of ints, but i cant get it right, here is the sketch in openprocessing:

http://www.openprocessing.org/sketch/9715

and this is the code :

int cols = 20 ;
int rows = 30;
float[][] size = new float[cols][rows];
float[][] trans = new float[cols][rows];
void setup() {
size(400,800);
smooth();
background(0);
for(int i =1; i<cols; i++){
for(int j =1; j<rows; j++){
size[i][j] = random(2,15);
trans[i][j] = random(20,255);
}
}
noStroke();
}
void draw() {
background(0);
fill(255,0,0);
for(int i =0; i<cols; i++){
for(int j =0; j<rows; j++){
fill(255,0,0,trans[i][j]);
ellipse(i*(width/cols),j*(height/rows+1),size[i][j],size[i][j]);
}
}
shift();
}
void shift(){
//copy the rows
for( int i =0; i<cols; i++){
for(int j =rows-1; j>0; j--){
trans[i][j] = trans[i][j-1];
size[i][j] = size[i][j-1];
}
}
//fill the first row with new random data
for(int i =0; i<cols; i++){
size[i][0] = random(2,15);
trans[i][0] = random(20,255);
}
}

Any idea how to do this ?

Thanks !

Replies(6)

benj.n.su..

Re: Problem with for loops, i want my grid to move in float values not ints

5 months ago

I don't think you will be able to achieve this given your current implementation (which is quite clever actually!).

The reason why is that you are not actually moving the ellipses. Instead, what you've created is something akin to an LED display grid where you have constant positions in a grid and you are displaying the same ellipse through each successive position on the grid. This gives you the illusion of movement, but because the positions are of fixed spacing, you'll never be able to achieve smoother movement that you are seeking. You can see this more predominantly if you change your draw loop to the following:

void draw() {

background(0);
fill(255,0,0);
for(int i =0; i<cols; i+=1){
    for(int j =0; j<rows; j+=2){ //SPACE THE ROWS FARTHER APART
    fill(255,0,0,trans[i][j]);
    ellipse(i*(width/cols+1),j*(height/rows+1),size[i][j],size[i][j]);
    }
}
shift();
}

The only way I can think of to do what you would like is to start using classes. Take a look at the following examples:

1) FILE>>EXAMPLES>>BOOKS>>PROCESSING HANDBOOK>>UNITS 43-51>>43 STRUCTURE 4>>EX_6

2) FILE>>EXAMPLES>>BOOKS>>PROCESSING HANDBOOK>>UNITS 43-51>>43 STRUCTURE 4>>EX_10

Instead of individual balls, you might create a class that displays a row of ellipses and then move the position of that row.

GoToLoop

Re: Problem with for loops, i want my grid to move in float values not ints

5 months ago

Here's a partial defective "solution". But maybe that can get you nearer an ideal solution:

Also, see it online -> http://studio.processingtogether.com/sp/pad/export/ro.93OhcRHbxDyHU/latest

// 70's Space Boogie
// by TweakingKnobs / GiorgioMartini
// mod GoToLoop

// http://forum.processing.org/topic/
// problem-with-for-loops-i-want-my-grid-to-move-in-float-values-not-ints

// http://studio.processingtogether.com/sp/pad/export/ro.93OhcRHbxDyHU/latest

final static byte COLS = 20, ROWS = 30;
final static byte[][]  dim = new byte[COLS][ROWS];
final static short[][] trans = new short[COLS][ROWS];

final static byte  MIN_SIZE = 010, MAX_SIZE = 020;
final static short MIN_ALPHA = 20, MAX_ALPHA = 0400;

final static byte  FPS = 0150;
final static color BG  = 0, FG = #FF0000;

// use JAVA2D instead of P2D for Processing 2+:
final static String GFX = P2D;

void setup() {
  size(400, 800, GFX);
  smooth();
  noStroke();
  frameRate(FPS);

  for (int i=0; i!=COLS; i++)
    for (int j=0; j!=ROWS; j++) {
      dim[i][j] = (byte) random(MIN_SIZE, MAX_SIZE);
      trans[i][j] = (short) random(MIN_ALPHA, MAX_ALPHA);
    }
}

void draw() {
  int scroll = ++frameCount % (MAX_SIZE - 2) * 2;

  if (scroll == 0) {
    reshift();
    refill();
  }

  background(BG);

  for (int i=0; i!=COLS;  i++)
    for (int j=0; j!=ROWS; j++) {
      fill(FG, trans[i][j]);
      ellipse(width/(COLS-1) * i, 
      height/(ROWS-1) * j + scroll, 
      dim[i][j], dim[i][j]);
    }
}

void reshift() {
  // copy the rows:
  for (int i=COLS; i--!=0;)
    for (int j=ROWS; --j!=0;) {
      trans[i][j] = trans[i][j-1];
      dim[i][j] = dim[i][j-1];
    }
}

void refill() {
  // fill the first row with new random data:
  for (int i=0; i!=COLS; i++) {
    dim[i][0] = (byte) random(MIN_SIZE, MAX_SIZE);
    trans[i][0] = (short) random(MIN_ALPHA, MAX_ALPHA);
  }
}

benj.n.su..

Re: Problem with for loops, i want my grid to move in float values not ints

5 months ago

if you have a moment, can you briefly explain why your implementation works? what is the change that is the key? i would not have expected that you could have achieved that using the grid implementation. full disclosure: my expectations are often incorrect.