Sine Wave

/**
 * Sine Wave
 * by Daniel Shiffman.  
 * 
 * Render a simple sine wave. 
 */
 
int xspacing = 16;   // How far apart should each horizontal location be spaced
int w;              // Width of entire wave

float theta = 0.0;  // Start angle at 0
float amplitude = 75.0;  // Height of wave
float period = 500.0;  // How many pixels before the wave repeats
float dx;  // Value for incrementing X, a function of period and xspacing
float* yvalues;  // Using an array to store height values for the wave

void setup() {
  size(640, 360);
  w = width + 16;
  dx = (TWO_PI / period) * xspacing;
  yvalues = new float[w / xspacing];
}

void draw() {
  background(0);
  calcWave();
  renderWave();
}

void calcWave() {
  // Increment theta (try different values for 'angular velocity' here
  theta += 0.02;

  // For every x value, calculate a y value with sine function
  float x = theta;
  for (int i = 0; i < w / xspacing; i++) {
    yvalues[i] = sin(x) * amplitude;
    x += dx;
  }
}

void renderWave() {
  noStroke();
  fill(255);
  // A simple way to draw the wave with an ellipse at each location
  for (int x = 0; x < w / xspacing; x++) {
    ellipse(x * xspacing, height/2 + yvalues[x], 16, 16);
  }
}