using noLoop() and millis() to draw words from txt by random

Programming Questions

johannes23

using noLoop() and millis() to draw words from txt by random

in Programming Questions • 1 year ago

hello there,

this is my first processing project …

what i like to do is to:

1. load a text file wich contains words (one word per row) - this works for me

2. select one word by random and display it for a short amount of time on the canvas - this works for me too

3. repeat this process n-times - - works for me too

4. pause this process (stop the loop) and display the current word for about 2-5 seconds - works for me too

5. start the loop again - this works NOT for me

hope you get the idea.

i tried it with loop() and noLoop() to start and stop the word selection and displaying. this seems not work as

millis() (which i use for the timing) stops working as soon as the loop stops. is there any workaround?

or is it more efficient to use a while loop instead?

the code:

String words[];

int pauseInt = 5000;;

int waitInt = pauseInt + 2000;;

void setup() {

size(800, 450);

background(255);

frameRate(30);

smooth();

textFont(createFont("Helvetica",50));

fill(0);

textAlign(CENTER, CENTER);

words = loadStrings("text.txt");

loop();

}

void draw(){

int selString;

background(255);

selString = (int)random(words.length);

text(words[selString], 400, 200);

if( millis() > pauseInt){

noLoop();

pauseInt = millis() + 5000;

}else{

loop();

}

thanks for your help.

grettings,

johannes

Replies(7)

v.k.

Re: using noLoop() and millis() to draw words from txt by random

1 year ago

I would try something like this:

int now;
int timeToDisplay = 1000;
void setup()
{
smooth();
background(255);
fill(random(0, 256), random(0, 256), random(0, 256));
noStroke();
ellipse(width/2, height/2, 50, 50);
now = millis();
}
void draw()
{
background(255);
while (millis () - now < timeToDisplay)
{
ellipse(width/2, height/2, 50, 50);
}
// here instead of picking a color, pick a new index for words array
fill(random(0, 256), random(0, 256), random(0, 256));
now = millis();
}

johannes23

Re: using noLoop() and millis() to draw words from txt by random

1 year ago

thanks for reply v.k.,

in your example i have some trouble to understand how time is handled.

in the expression of while you compare ( millis() - now) against the timetodisplay var.

but isn't now equal to millis, as you assign it to millis at the bottom of your code, no?

i assume that all instances of millis holds the same value in ms(elapsed time since

program-start), right…¿

could you please elaborate this.

thanks, j

PhiLho

Re: using noLoop() and millis() to draw words from txt by random

1 year ago

" isn't now equal to millis, as you assign it to millis at the bottom of your code, no?"
A program is sequential, from top to bottom.
When the test is done, now has the value of millis() from the previous frame, some 1/30th of second ago. Then the next instructions are executed, then now gets the new, current value of millis(). After that, draw() exits, and is called again some 1/30th of second later (assuming default frame rate), with now having retained the value it had at the end of draw().

johannes23

Re: using noLoop() and millis() to draw words from txt by random

1 year ago

"A program is sequential, from top to bottom.
When the test is done, now has the value of millis() from the previous frame…"

i see.

but using a while loop (like v.k.´s example demonstrates) makes one of my cpu´s jumps up to 100% -

the high cpu utilization seems to be caused by the subtraction in the while expression. did i miss

something important here?

thanks guys,

)ohannes

the while loop version of my project:

String words[];

int pauseInt;

int now;

int timeToDisplay = 50;

int selString;

void setup() {

size(800, 450);

background(255);

frameRate(30);

textFont(createFont("Helvetica",50));

fill(0);

textAlign(CENTER, CENTER);

words = loadStrings("text.txt");

loop();

now = millis();

selString = 0;

pauseInt = 8000;

smooth();

}

void draw(){

background(255);

while (millis () - now < timeToDisplay){

selString = (int)random(words.length);

}

if (millis() > pauseInt){

pauseInt = millis() + 8000;

timeToDisplay = 3000;

}else{timeToDisplay = 50;

}

text(words[selString], 400, 200);

now = millis();

}

PhiLho

Re: Re: using noLoop() and millis() to draw words from txt by random

1 year ago

I totally overlooked the while statement, this is usually done with a simple if in place of the while!

v.k.

Re: using noLoop() and millis() to draw words from txt by random

1 year ago

edit: i wrote before seeing your reply.

The while loop has always confused me a little. The same effect could be done like:

if (millis () - now < timeToDisplay)
{
ellipse(width/2, height/2, 50, 50);
} else
{
// here instead of picking a color, pick a new index for words array
fill(random(0, 256), random(0, 256), random(0, 256));
now = millis();
}

Because when the program enters a while loop it stays there executing the code inside the block until condition is met. So the lines after a while loop are only executed when the condition in previous while is achieved. Only then now is reassigned to real time again.

This has side effects. If you need to, let's say, animate another ellipse running in the bottom of the screen you would have to make it before the while loop, if added below, it would have to wait the same time to be executed.

Though with the if/else approach this wouldn't happen. Codes go trough an if statement. If condition mets code inside is executed once and the next line after the if block is executed and so on, else if don't met, code inside the else block is executed once and the program flows. Try, you will see. This is why while is "dangerous" cause it is prone to end in an endless loop, and the program stalls... So you need to be sure that the code that will make the condition to be met is inside the while block. Or independent , like a user action or, the time. Used in this example.

v.k.

Re: using noLoop() and millis() to draw words from txt by random

1 year ago

I agree. I should have not used while first place... Any way it takes an else together with the if to work. right?

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