function setup() {

  createCanvas(400, 400);

  points = [];

  var sides = 4;

  var stepSize = TWO_PI / sides;

  var angle = radians(45);

  var radius = 100;

  for(var i = 0; i < sides; i++, angle += stepSize) {

    points.push({

        x: radius * sin(angle),

      y: radius * cos(angle)

    });

  }

  applyTransform('HORIZONTAL', 25.820992);

}

​

function applyTransform(type, angle) {

  if(type === 'HORIZONTAL') {

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

        var p = points[i];

      p.x = (p.x * 1) + (p.y * tan(angle));

      p.y = (p.x * 0) + (p.y * 1);

    }

  }

  else {

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

        var p = points[i];

      p.x = (p.x * 1) + (p.y * 0);

      p.y = (p.x * tan(angle)) + (p.y * 1);

    }

  }

}

​

function draw() {

  background(220);

  translate(width / 2, height / 2);

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

    var p1 = points[i];

    var p2 = points[(i + 1) % points.length];

    line(p1.x, p1.y, p2.x, p2.y);

  }

}