What is the equation behind the PVector.rotate(float)?

Althalus7

Hi all, Was just wondering what the equation behind the PVector.rotate(float) was. Thank you in advance. Here is link to source https://processing.org/reference/PVector_rotate_.html

koogs

that says it's 2d only so it'll apply the standard 2d rotation matrix to the 2d vector

https://en.wikipedia.org/wiki/Rotation_matrix

Althalus7

Thank you, I'll see if I can put it in my code.

GoToLoop

We can read rotate()'s implementation at this link below: B-)
https://GitHub.com/processing/processing/blob/master/core/src/processing/core/PVector.java#L917

public PVector rotate(float theta) {
  float temp = x;
  x = x*PApplet.cos(theta) - y*PApplet.sin(theta);
  y = temp*PApplet.sin(theta) + y*PApplet.cos(theta);
  return this;
}

Anyways, I've adapted it from Java to JS. Take a look: :ar!

PVector.prototype.rotate = function(ang, t) {
  const c = Math.cos(ang),
        s = Math.sin(ang),
        x = c*this.x - s*this.y,
        y = s*this.x + c*this.y;
  t === null && (t = new PVector);
  return (t || this).set(x, y);
};

Althalus7

Thank you also, that is something i think i can work with