sincoslookup taken from http://wiki.processing.org/index.php/Sin/Cos_look-up_table

archived version http://web.archive.org/web/20130510100827/http://wiki.processing.org/w/Sin/Cos_look-up_table

*/

​

// declare arrays and params for storing sin/cos values 

let sinLUT;

let cosLUT;

// set table precision to 0.5 degrees

const SC_PRECISION = 0.5;

// caculate reciprocal for conversions

const SC_INV_PREC = 1 / SC_PRECISION;

// compute required table length

const SC_PERIOD = Math.floor(360 * SC_INV_PREC);

​

// init sin/cos tables with values

// should be called from setup()

function initSinCos() {

  sinLUT = [];

  cosLUT = [];

  for (let i = 0; i < SC_PERIOD; i++) {

    sinLUT[i] = sin(i * DEG_TO_RAD * SC_PRECISION);

    cosLUT[i] = cos(i * DEG_TO_RAD * SC_PRECISION);

  }

}

​

// circle radius used for example

let radius;

​

function setup() {

  createCanvas(200, 200);

  initSinCos(); // important call to initialize lookup tables

}

​

function draw() {

  background(255);

  // modulate the current radius

  radius = 50 + 50 * sinLUT[frameCount % SC_PERIOD];

​

  // draw a circle made of points (every 5 degrees)

  for (let i = 0; i < 360; i += 5) {

    // convert degrees into array index:

    // the modulo operator (%) ensures periodicity 

    let theta = int((i * SC_INV_PREC) % SC_PERIOD);

    // draw the circle around mouse pos

    point(

      mouseX + radius * cosLUT[theta],

      mouseY + radius * sinLUT[theta]

    );

  }

}