In this simple program, we animate an ellipse to always chase a point defined by the mouse. The ellipse only ever moves a percentage of the distance between it and the target destination in each step. The p5.Vector object is used to handle the coordinates and the simple math operations.

var pos;
var targetPos;
var mousePos;

function setup() {
  createCanvas(1000, 600);
  fill(0);
  pos = createVector(0, 0);
  targetPos = createVector(0, 0);
  mousePos = createVector(width/2, height/2);
}

function draw() {
  background(255);
  targetPos.set(mousePos); 
  targetPos.sub(pos);  // find the vector between mouse position and ellipse position
  targetPos.mult(0.2); // each step in the animation will move this percentage of the distance to the target position
  pos.add(targetPos);
  ellipse(pos.x, pos.y, 60, 60);
}

function mousePressed() {
  mousePos.set(mouseX, mouseY);
}


Exercise 

  1. Add an additional ellipse that follows the mouse at a slower rate than the first ellipse. 
  2. Modify the code so that the ellipse always follows the mouse position.  
  3. Replace with the ellipse with another shape (like a triangle or even a car) , and keep it pointed towards the mouse.

Exercise Solution Using Arrays

var pos = [];
var targetPos = [];
var mousePos = [];
var arrayLength = 5;

function setup() {
  createCanvas(1000, 600);
  fill(0);
  for (var i = 0; i< arrayLength; i++) { 
    pos[i] = createVector(0, 0);
    targetPos[i] = createVector(0, 0);
  }
   mousePos = createVector(width/2, height/2);
}

function draw() {
   mousePos.set(mouseX, mouseY);
   background(255);
  
  for (var i = 0; i < pos.length; i++) { 
        targetPos[i].set(mousePos); 
        targetPos[i].sub(pos[i]);  // find the vector between mouse position and ellipse position
        targetPos[i].mult((i*0.02) + 0.05); // each step in the animation will move this percentage of the distance to the target position
        pos[i].add(targetPos[i]);
        fill(125,255,23);
        ellipse(pos[i].x, pos[i].y, 60, 60);
    }
}


Solution using a class. 

classExample.zip