Problem of display in a " for" loop

Processing Beginners
1

Hello everybody

i am not a beguiner in programing, but i am a beguinner in processing

I try to move a text in a FOR loop but the drawing is not refresh, only at the end of the loop

i try to add redraw() in my loop but without sucess.

i know that i can use only the “draw” loopto do that but it may be usefull to do it in the loop

what to do?

thanks for your answers

here the code

void setup() {
  size(640, 600); 
  background(51);
}
void draw() 
{
   fill(255, 212,0);
  for (int a = 1 ; a<300; a = a+10 )
    {  
     text("Hello World",a,a);
    delay(10);
    }
}

thanks and have a nice day

Sébastien

1 Like
2

Hi,
Actually the draw() function is already a loop that renders an image. See https://processing.org/reference/draw_.html

What you can do is update your a variable once at the beginning of the draw function. For example


int a = 1;
int delta = 10;

void setup() {
  size(640, 600);
  background(51);
}
void draw()
{
  //Background fills the canvas
  background(51);
  fill(255, 212, 0);
  //allows to keep a inside the canvas
  if (a > height) delta = -10;
  else if (a < 0) delta = 10;
  a += delta;

  //print hello world
  text("Hello World", a, a);
}
1 Like
3

Thanks for your anwser.

i know that i could do it the draw

does that mean that there are no other way to refresh the draw at another moment in the code?

even if it s not Processing philosophie, i would like to do it simply in a loop.

it a for ilustrate a for loop. i give a very simple coding initiation to some students tomorrow

thanks and best regards,

Sébastien

4

Try this as an example

int a = 0;

void setup() {
  size(640, 600);
}

void draw() {
  background(51);
  fill(255, 212, 0);
  a ++;
  a %= 300;
  text("Hello World", a, a);
}
1 Like
5

Ok I understand. I don’t think that’s possible without using tricks that would loose the purpose of being simple.

Maybe this way? And removing the setup() & draw()


background(51);
size(640, 600);

for (int a = 0; a < 255; a+=10){
  fill(a, a, a);
  text("Hello world : " + a, a, a); 
}
6

Thanks

it don t change anything without been outside draw {}. it s write everything and display at the end

but may be the solution is to indicate the index (a) in the text fonction so students will understand the loop even if it s not like i would like

thanks and have a nice evening (it s 21 here)

Sébastien

7

The draw() function loops once per frame.