How do i get the waveforms to go all the way across the screen? Why are they only going across half of the screen?

Here is the code:

import ddf.minim.*;

Minim minim;
AudioInput in;


void setup()
{
  size(1050, 550, P2D);

  minim = new Minim(this);
  minim.debugOn();

  // get a line in from Minim, default bit depth is 16
  in = minim.getLineIn(Minim.STEREO, 512);
}

void draw()
{
  background(0);
  stroke(255);
  noFill();
  smooth();

  sum = 0;

  // draw the waveforms
  for(int i = 0; i < in.bufferSize() - 1; i++)
  {
 
    line(i, height/2 + in.left.get(i)*height, i+1, height/2 + in.left.get(i+1)*height);
  }
}


void stop()
{
  // always close Minim audio classes when you are done with them
  in.close();
  minim.stop();

  super.stop();
}