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Index › Programming Questions & Help › Syntax Questions › 2 questions from a beginner ...
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2 questions from a beginner ... (Read 487 times)
amelia
2 questions from a beginner ...
Nov 29th, 2007, 2:20pm  
Hi,

I would like to know get advice how to do the following:

With a forloop: How do I continuously change the values of the actual forloop - i.e. if the forloop controls the amount of lines drawn, then there could be more or less lines:
for(int j=0; j<50; j+=lines) {   }

- I have tried the above, but nothing is drawn to the screen - the variable lines has to be a set number (set in the setup) that does not change over time ...

this doesn't really work:

for(int j=0; j<50; j+=mouseX) {   }


2) How do I make a non-linear counter?

cnt = cnt + ( speed * countdir ); // here the speed is linear, because it is a set value ...

   if (cnt > maxVal || cnt < 0) {
     countdir *= -1;
   }

Thank you so much for your help!
Amelia
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JohnG
Re: 2 questions from a beginner ...
Reply #1 - Nov 29th, 2007, 2:58pm  
a: Code:
int lines=25; //draw 25 lines.
for(int j=0;j<lines;j++)
{ 
  // draw a line
}


b: I'm not quite sure what you mean....
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antiplastik
Re: 2 questions from a beginner ...
Reply #2 - Nov 29th, 2007, 6:04pm  
Hi,

Try with the random method :
http://processing.org/reference/random_.html

For example :
Code:
 for(int j=0; j<50; j+=(int)(1+random(2))) {   }


The same method applies to the counter as well ;-)
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didi
Re: 2 questions from a beginner ...
Reply #3 - Nov 29th, 2007, 6:49pm  
One way would be to:

void setup()
{
 size(500, 500);
 background(255);
}


void draw()
{
 background(255);
 stroke(255, 0, 0);
 
 //dont't change the increment step, change the loop's
 //outer limit

 for(int i = 0; i<mouseX/5; i++)
 {
   line(i*5, 0, 0, i*5);
 }
}
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amelia
Re: 2 questions from a beginner ...
Reply #4 - Nov 30th, 2007, 10:52am  
Thank you, that was useful! However, I still don't know how to solve the problem of the distance between the lines:

for(int j=0; j<mouseX/10; j+3) // here the number 3 could be a variable distance between the lines ...

How do I make the distance between the lines happen realtime?

Tnx, amelia
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antiplastik
Re: 2 questions from a beginner ...
Reply #5 - Nov 30th, 2007, 11:13am  
If you don't want random spaces between line, but real time, user defined spaces, you cannot do that in a for loop.

Try with a global variable you increment at each frame :

Code:
int x = 0;

void setup() {
  background(255);
  stroke(0);
  frameRate(5);
}

void draw() {
  if (x < width) {
    x += (int)(mouseX/10);
    line(x, 0, x, height);
  }
}
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