Basic easing in Processing

easing.pde

float x;
float y;
// This is the easing factor, the more the faster the (x, y) reach the target
float easing = 0.05;

void setup() {
  size(640, 360); 
  noStroke();  
}

void draw() { 
  background(51);
  
  // the eventual targeted x-coordinate for the circle (the mouse's position)
  float targetX = mouseX;
  
  // delta of x: as the frame loops, dx becomes less and less 
  float dx = targetX - x;
  
  // Progress the circle's x coordinate by delta x times easing factor per frame
  // as it approaches the targetX, dx keeps decreasing and so is x
  x += dx * easing;
  
  // Same goes with Y
  float targetY = mouseY;
  float dy = targetY - y;
  y += dy * easing;
  
  ellipse(x, y, 66, 66);
}