// by progressively deleting all vertices along a resampled circle

// except for three vertices (representing the triangle's corners)

​

var xpoints = [];

var ypoints = [];

var npointsInit = 240;

var deleteAtIndex;

var bTransformingFromCircleToTriangle;

var notTransformingCount;

var bShowDebug;

​

//------------------------------------------

function setup() {

  createCanvas(400, 400);

  bTransformingFromCircleToTriangle = false;

  bShowDebug = false;

  initialize();

}

​

//------------------------------------------

function draw() {

  background(255, 255, 255);

  noFill();

  stroke(0);

  strokeWeight(3);

​

  push();

  translate(width / 2, height / 2);

  rotate(-HALF_PI);

  beginShape();

  for (var i = 0; i < xpoints.length; i++) {

    var px = xpoints[i];

    var py = ypoints[i];

    vertex(px, py);

  }

  endShape(CLOSE);

​

  if (bTransformingFromCircleToTriangle) {

    deleteAtIndex--;

    if ((deleteAtIndex == (2 * npointsInit / 3)) || (deleteAtIndex == (npointsInit / 3))) {

      deleteAtIndex--;

    }

    xpoints.splice(deleteAtIndex, 1);

    ypoints.splice(deleteAtIndex, 1);

    if (xpoints.length == 3) {

      bTransformingFromCircleToTriangle = false;

    }

  }

  pop();

​

  drawDebug();

​

  if (!bTransformingFromCircleToTriangle) {

    notTransformingCount++;

    if (notTransformingCount > 60) {

      mousePressed();

    }

  }

}

​

//------------------------------------------

function mousePressed() {

  if (bTransformingFromCircleToTriangle || (xpoints.length == 3)) {

    bTransformingFromCircleToTriangle = false;

    initialize();

  } else {

    bTransformingFromCircleToTriangle = true;

    deleteAtIndex = npointsInit - 1;

    notTransformingCount = 0;

  }

}

​

//------------------------------------------

function initialize() {

  notTransformingCount = 0;

  var radius = (width / 2) * 0.75;

  for (var i = 0; i < npointsInit; i++) {

    var t = map(i, 0, npointsInit, 0, -TWO_PI);

    var px = radius * cos(t);

    var py = radius * sin(t);

    xpoints[i] = px;

    ypoints[i] = py;

  }

}

​

//------------------------------------------

function keyPressed() {

  bShowDebug = !bShowDebug;

}

​

//------------------------------------------

function drawDebug() {

  if (bShowDebug) {

    push();

    translate(width / 2, height / 2);

    rotate(-HALF_PI);

    strokeWeight(1);

    stroke(255, 0, 0, 64);

    for (var i = 0; i < xpoints.length; i++) {

      line(0, 0, xpoints[i], ypoints[i]);

    }

    pop();

  }

}