size (400,400);
background (0);
//smooth();

// create array of ints to describe a line
// x1. y1, x2, y2
float[] line1 = new float[4];
float[] line2 = new float[4];

// setup for slight color varience between cycles
float [] strokeColor = {10,10,10};
int strokeAdd = 20;

for (int numcyc=0; numcyc<6; numcyc++) {
  
  for (int k=0; k<3; k++) {
  strokeColor[k] = strokeColor[k] + (strokeAdd + random(20));
  stroke (strokeColor[0], strokeColor[1], strokeColor[2]);
  }
  // fill the array by addressing the location of the array and giving it a value
  // note that the array starts at position 0 and goes to 3
  // even though you initialized the array with the number 4
  // summary: 4 positions, numbered 0 through 3
  for (int j=0; j<4; j++) {
    line1[j] = random(0,400);
  }

  // find slope of line m = y2-y1 / x2 - x1
  float slope1;
  slope1 = (line1[3] - line1[1])/(line1[2] - line1[0]);
  println ("slope of first line: " + slope1);

  // draw out that line by referencing the values now stored in the array
  strokeWeight (3);
  line (line1[0], line1[1], line1[2], line1[3]);
  strokeWeight(1);
  
  // draw a given (numlines) number of lines using formula below
  for (int numlines=0; numlines<200; numlines++) {

    // generate random # for line2 point 1 x value within range of line1 x values
    line2[0] = random (line1[0], line1[2]);
    // find x for that value of y based on equation for line1
    // y=m(x-x1) + y1
    line2[1] = (slope1 * (line2[0] - line1[0])) + line1[1]; 
    // randomly generate second point for line2. The reason it looks like pine needles is that
    // the end point of the first line is telling the ends of the smaller lines to cluster around it
    
    line2[2] = line1[2] + random(-100,100);
    line2[3] = line1[3] + random(-100,100);
    
    // find slope of new line
    float slope2 = (line2[3] - line2[1])/(line2[2] - line2[0]);
    //  println ("slope of second line: " + slope2);

    // Check if lines are parallel (slopes are equal), if so, don't continue with program
    if (slope1 != slope2) {
        for (int k=0; k<3; k++) {
          // small variance in needle color
          strokeColor[k] = strokeColor[k] + random (-3, 3);
          stroke (strokeColor[0], strokeColor[1], strokeColor[2]);
        }
      line (line2[0], line2[1], line2[2], line2[3]);
    }
  }
}