I have a class, Point2d, and a function, drawPoint2d:

class Point2d {
  float x, y;
  Point2d (float x, float y) {
    this.x = x;
    this.y = y;
  }
}
void drawPoint2d (Point2d p) {
  ellipse (p.x, p.y, 10, 10);
}

And they seem to work fine:

void setup () {
  drawPoint2d (new Point2d (10, 10));
  //Point2d p = new Point2d (10, 10);
  //drowPoint2d (p);
}

However, if I were to uncomment the two commented lines, I'd receive an error message reading "The function drawPoint2d(AnExampleSketch.Point2d) does not exist.", with "AnExampleSketch" being the name of my sketch.

Why would this be? I'm using Processing 2.0, and I don't remember if I've encountered a similar error before.