draw a square wave?

Programming Questions

njitram

in Programming Questions • 1 year ago

is there an easy way to draw a square wave in processing where I can adjust the frequency and amplitude?

Replies(7)

allonestr..

Re: draw a square wave?

1 year ago

You could ...

• create a function which takes the period and amplitude and draws an up, an across, a down, an across and an up, and call this function several times

• create a class and pass it the period and amplitude and draws ditto

• ...

njitram

Re: draw a square wave?

1 year ago

Could you give a small example with, for example, the mouseX as amplitude and mouseY as frequency. I tried but couldnt figure it out

novelty_a..

Re: draw a square wave?

1 year ago

Here ya go.

float freq = .001;
float ampl = .25;
void setup()
{
size(300,200);
smooth();
}
void draw()
{
background(255);
stroke(0);
noFill();
float sqSize = 9;
for (float x = sqSize/2; x < width; x += sqSize*2) {
float r1 = noise(x,0,millis()*.0001);
float r2 = sin(millis()*freq+x*TWO_PI/width)*height*ampl;
pushMatrix();
translate(x,height/2+r2);
rotate(degrees(r1));
rect(0,0,sqSize,sqSize);
popMatrix();
}
}

njitram

Re: draw a square wave?

1 year ago

Thats a sine wave with squares on it :)

I meant something like allonestring made

jbum

Re: draw a square wave?

1 year ago

Here is a drop in replacement for sin() that produces square waves instead of sine waves. You can drop it into any code that uses sine, and you'll get a square wave.

float sqw(float a)

{

a /= TWO_PI;

a -= int(a);

return a < .5? -1 : 1;

}

Here's one for sawtooth.

float sawtooth(float a)

{

a /= TWO_PI;

a -= int(a);

return map(a,0,1,-1,1);

}

PS. I think the sine wave made of squares is genius, and you should just go with that.

PhiLho

Re: draw a square wave?

1 year ago

Show your attempt. Hint: it is just a matter of doing 5 or 6 line() calls.

toxmeister

toxiclibs has a few wave generators on offer, including digital square waves and "analogue" ones (i.e. based on summing harmonics)... the snippet below shows how to use them in principle (just do wave.update() to get the next value)...

import toxi.math.waves.*;
int fps=60;
// frequency for waves needs to be given in radians, but we can use this function to convert from Hz
float freq=AbstractWave.hertzToRadians(2, fps);
AbstractWave wave;
void setup() {
size(500, 400);
frameRate(fps);
// digital square wave
wave=new FMSquareWave(0, freq, 100, height/2);
// or based on harmonics
//wave=new FMHarmonicSquareWave(0, freq, 100, height/2);
//((FMHarmonicSquareWave)wave).maxHarmonics=15;
}
void draw() {
int x=frameCount%width;
if (0==x) background(255);
if (0==frameCount%fps) line(x, 0, x, height);
line(x, height/2, x, wave.update());
}

Also recommend checking out the AdditiveWaves demo bundled with the library or available on OpenProcessing here:

http://openprocessing.org/visuals/?visualID=8876

http://postspectacular.com | http://toxiclibs.org

Top Reply