spiraling a sphere (2025)

// make source public, Spring 2025

// schien@mail.ncku.edu.tw

​

// Example code for lecture "Adding Dimensions"

// an example from Pearson (2011)

// the wrong way to draw a sphere that achieves spirals

// schien@mail.ncku.edu.tw, DPD 2023

​

let radius = 100;

​

function setup() {

  createCanvas(500, 300, WEBGL);

  stroke(0);

}

​

function draw() {

  background(255);

  rotateY(frameCount * 0.03);

  rotateX(frameCount * 0.04);

  let s = 0;

  let t = 0;

  let lastx = 0;

  let lasty = 0;

  let lastz = 0;

  while (t < 180) {

    s += 18;

    t += 1;

    let radianS = radians(s);

    let radianT = radians(t);

    let thisx = 0 + radius*cos(radianS)*sin(radianT);

    let thisy = 0 + radius*sin(radianS)*sin(radianT);

    let thisz = 0 + radius*cos(radianT);

    if (lastx != 0) {

      line(thisx, thisy, thisz, lastx, lasty, lastz);

    }

    lastx = thisx;

    lasty = thisy;

    lastz = thisz;

  }

}