PIXI circles

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.4.0/pixi.js"></script>
<script src="https://rawgit.com/matt-way/gifuct-js/master/dist/gifuct-js.min.js"></script>

JavaScript

var app = new PIXI.Application(500, 500, {backgroundColor:0x000000});
document.body.appendChild(app.view);


var character, state, mousePosition;
character = {};
var mousePosition = app.renderer.plugins.interaction.mouse.global;

setup();

function setup() {
  character.core = new PIXI.Graphics()
    .beginFill(0xdc143c)
    .drawCircle(0, 0, 5);

  character.core.position.x = app.screen.width / 2 + 10;
  character.core.position.y = app.screen.height / 2;

  character.shield = new PIXI.Graphics()
    .lineStyle(5, 0x67c8ff, 1)
    .drawCircle(0, 0, 50);

  character.shield.position.x = app.screen.width / 2;
  character.shield.position.y = app.screen.height / 2;

  character.x = app.screen.width / 2;
  character.y = app.screen.height / 2;
  app.stage.addChild(character.core);
  app.stage.addChild(character.shield);
  character.vx = 0;
  character.vy = 0;
  character.radius = character.shield.graphicsData[0].shape.radius;
  character.width = character.core.graphicsData[0].shape.width;
  character.height = character.core.graphicsData[0].shape.height;

  character.score = 0;
  character.energy = 4;
  character.energyGen = 0.005;
  character.health = 100;

  character.getX = function() {
    return this.x;
  };
  character.setX = function(x) {
    this.x = x;
  };
  character.getY = function() {
    return this.y;
  };
  character.setY = function(y) {
    this.y = y;
  };

  character.getShieldRadius = function() {
    return this.shield.graphicsData[0].shape.radius;
  };
  character.setShieldRadius = function(radius) {
    this.shield.graphicsData[0].shape.radius = radius;
  };

  character.canMoveX = function(newX) {
    return true;
  };
  character.canMoveY = function(newY) {
    return true;
  };

  character.lookAtMouse = function() {
    let lookX = mousePosition.x - this.getX();
    let lookY = mousePosition.y - this.getY();
    let lookAngle = Math.atan2(lookY, lookX);
    this.core.rotation = lookAngle;
  };

  character.updateEnergy = function() {
   ...