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Index › Programming Questions & Help › Syntax Questions › Moving Sine Wave (Beginner)
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Moving Sine Wave (Beginner) (Read 1341 times)
Si_Long
Moving Sine Wave (Beginner)
Feb 16th, 2010, 6:01pm  
Hi,

I'm having difficulties creating an oscillating sine wave.
(Actually, I haven't the faintest idea how to go about this, though I think I may have to create a function...) Advice would be greatly appreciated. Here's what I have so far--the static sine wave:

void setup (){
 size(400, 400);
 background(0);
 noStroke();
 fill(255,50);
}

void draw(){

 for (float x = 0; x < 3*TWO_PI; x+=0.02) {
   // Calculate value
   float y = sin(x);
   // Render wave using ellipse.
   ellipse(x*21,height/2+y*50,16,16);
 }
}

(I'm only dimly aware of arrays, so if possible I'd like to avoid using them.)
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toxi
Re: Moving Sine Wave (Beginner)
Reply #1 - Feb 16th, 2010, 6:14pm  
Having the static wave done, you're already almost there. The only thing needed to animate the wave is by adding a moving offset to your input phase value for the sin() function, so like:

Code:
float y = sin(x+frameCount*0.1);

1) You also need to move the background() from setup() into draw() to get the correct effect...

2) You might also want to check out this:
http://toxiclibs.org/2009/12/additive-waves/
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Si_Long
Re: Moving Sine Wave (Beginner)
Reply #2 - Feb 16th, 2010, 6:23pm  
Thank you so much!
What exactly is 'frameCount', though? Since I didn't need to create a variable named 'frameCount', does that make it a pre-existing function?

(By the way, I looked at your website. It's rather...overwhelming. But very impressive. Smiley )
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Cedric
Re: Moving Sine Wave (Beginner)
Reply #3 - Feb 16th, 2010, 6:48pm  
frameCount is what it said. the Count of the Frames...
it is often used if you need an increasing variable. instead of creating a variable X and count it up every frame, you can just use frameCount.
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PhiLho 
Re: Moving Sine Wave (Beginner)
Reply #4 - Feb 17th, 2010, 12:44am  
Si_Long wrote on Feb 16th, 2010, 6:23pm:
does that make it a pre-existing function

No. That's a pre-existing... variable! Processing has lot of them, from width, height, to sketchPath or g.
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TfGuy44
Re: Moving Sine Wave (Beginner)
Reply #5 - Feb 17th, 2010, 2:27am  
I love g.  Grin

Also, cool sin wave!
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monsieurBlutbad
Re: Moving Sine Wave (Beginner)
Reply #6 - Feb 18th, 2010, 11:49pm  
slightly out of topic, but I'm curious what is g.?
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TfGuy44
Re: Moving Sine Wave (Beginner)
Reply #7 - Feb 19th, 2010, 1:10am  
g is the default PGraphics object. Your calls to things like fill() or beginDraw(), etc, are actually calls to g.fill() or g.beginDraw(), g.etc.
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