float offset = 30*PI/180;   
float shrinkFactor = 0.7;



int    maximumBranchouts = 4;
float  maximumBranchAngle = 2*PI/4.0;
int    maximumHeight = 8;

void branch(int startX, int startY, int branchLength, float angle, int size) {
  if (size == 0) return;
    strokeWeight(size);
  if (size > 1) {
    stroke(80, 50, 20);
  }
  else {
   // strokeWeight(1);
    stroke(0,80+int(random(50)),0);
  }

  int endX = startX + int(branchLength * cos(angle));
  int endY = startY + int(branchLength * sin(angle));
  line(startX, startY, endX, endY);
  if (size<4) {
    stroke(0,80+int(random(50)),0);
    ellipse(endX,endY, random(size*8),random(size*5));
  }
  
  
  
  int branches = int(random(maximumBranchouts - 1)) + 2;
  float branchShrink = 0.5 + random(1)/2;
  for (int i=0; i<branches; i++)
    branch(endX, endY, int(branchLength * branchShrink), angle + random(maximumBranchAngle) - maximumBranchAngle/2, size-1);
}

void setup() {
  size(600, 600);
  frameRate(1);
}

void draw() {
  background(160,200,255);                                  // Draw sky
  fill(0, 80, 0);  rect(0,height-120, width, height);       // Draw grass
  branch(width/2, height-100, 50, -PI/2, maximumHeight);    // Draw tree trunk = 90 pixels
}