// The Nature of Code // Daniel Shiffman // http://natureofcode.com // Recursive Tree // Renders a simple tree-like structure via recursion // Branching angle calculated as a function of horizontal mouse position var theta; function setup() { createCanvas(640, 360); } function draw() { background(51); // Let's pick an angle 0 to 90 degrees based on the mouse position theta = map(mouseX,0,width,0,PI/2); // Start the tree from the bottom of the screen translate(width/2, height); stroke(255); //branch(120); branch(mouseY); // Y座標で深さを変えるようにしてみた } function branch(len) { // Each branch will be 2/3rds the size of the previous one var sw = map(len,2,120,1,10); strokeWeight(sw); //strokeWeight(2); line(0, 0, 0, -len); // Move to the end of that line translate(0, -len); len *= 0.66; // All recursive functions must have an exit condition!!!! // Here, ours is when the length of the branch is 2 pixels or less if (len > 2) { push(); // Save the current state of transformation (i.e. where are we now) rotate(theta); // Rotate by theta branch(len); // Ok, now call myself to draw two new branches!! pop(); // Whenever we get back here, we "pop" in order to restore the previous matrix state // Repeat the same thing, only branch off to the "left" this time! push(); rotate(-theta); branch(len); pop(); } }