Overlay script problème

Alors voila je viens de trouver un script pour faire de l'overlay mapping sur un site chinois et je l'aime beaucoup car il fonctionne exactement de la même façon que celui de Yami.
https://yamiworld.wordpress.com/yami-engine/image-display/overlay-mapping/

Seulement il y a un soucis, l'auteur de ce script n'a pas l'air de vouloir suivre le développement de ce script et il comporte un bug que j'aimerais bien voir résolu.

Le problème en lui même c'est que les images ne se cale pas comme il faut sur la map (bord trouble sur le coté droit de l'écran) et en plus il décale de façon aléatoire les tilesets en eux même.

Voici le code :

Code:

//=============================================================================
// Overlay.js
//=============================================================================
/*:
 * @plugindesc Overlay Mapping script by SWEBOK v1.1
 * @author SWEBOK
 *
 * @param Light Switch
 * @desc Turn on/off light layer
 * @default 1
 *
 * @param Parallax Switch
 * @desc Turn on/off parallax layer
 * @default 2
 *
 * @param Ground Switch
 * @desc Turn on/off ground layer
 * @default 3
 *
 * @param Light Variable
 * @desc Switch to another light
 * @default 1
 *
 * @param Parallax Variable
 * @desc Switch to another parallax
 * @default 2
 *
 * @param Ground Variable
 * @desc Switch to another ground
 * @default 3
 *
 * @help This plugin does not provide plugin commands.
 *
 * Last Updated: 10/27/2015
 *     v1.0 - 10/24/2015 - first release.
 *     v1.1 - 10/27/2015 - upper tilemap layer problem solved
 *
 * This script will automatically load map's overlay by map ID, and a map can have more than
 * one image per layer, so you don't have to create two or more map just for day/night or
 * when an event occur.
 *
 * Create a folder in img and name it overlay.
 * Put all of your overlay into img/overlay.
 * Your overlay file will have the name: "ground"/"par"/"light" + Map-ID + "-" + Number.
 * Map-ID is your map's ID.
 * Number is 1, 2, 3, ... using for Overlay Variables.
 *
 * Example: img/overlay/ground2-1.png
 *
 * All pictures must be .png
 */
 
 (function() {
 var parameters = PluginManager.parameters('Overlay');
 var lightSwitch = Number(parameters['Light Switch'] || 1);
 var parallaxSwitch = Number(parameters['Parallax Switch'] || 2);
 var groundSwitch = Number(parameters['Ground Switch'] || 3);
 var lightVariable = Number(parameters['Light Variable'] || 1);
 var parallaxVariable = Number(parameters['Parallax Variable'] || 2);
 var groundVariable = Number(parameters['Ground Variable'] || 3);
 
 ImageManager.loadOverlay = function(filename, hue) {
 return this.loadBitmap('img/overlay/', filename, hue, false);
 };
 
 ImageManager.isReady = function() {
 for (var key in this._cache) {
 var bitmap = this._cache[key];
 if (bitmap.isError()) {
 //throw new Error('Failed to load: ' + bitmap.url);
 bitmap = new Bitmap();
 return true;
 }
 if (!bitmap.isReady()) {
 return false;
 }
 }
 return true;
 };

 Spriteset_Map.prototype.createLowerLayer = function() {
 Spriteset_Base.prototype.createLowerLayer.call(this);
 this.createParallax();
 this.createTilemap();
 this.createOverlayGround();
 this.createCharacters();
 this.createOverlayParallax();
 this.createShadow();
 this.createOverlayLight();
 this.createDestination();
 this.createWeather();
 };
 
 Spriteset_Map.prototype.update = function() {
 Spriteset_Base.prototype.update.call(this);
 this.updateTileset();
 this.updateParallax();
 this.updateTilemap();
 this.updateOverlayGround();
 this.updateOverlayParallax();
 this.updateShadow();
 this.updateOverlayLight();
 this.updateWeather();
 };
 
 Spriteset_Map.prototype.createOverlayGround = function() {
 this._overlayGround = new TilingSprite();
 this._overlayGround.move(0, 0, Graphics.width, Graphics.height);
 this._tilemap._lowerLayer.addChild(this._overlayGround);
 };
 
 Spriteset_Map.prototype.createCharacters = function() {
 this._characterSprites = [];
 $gameMap.events().forEach(function(event) {
 this._characterSprites.push(new Sprite_Character(event));
 }, this);
 $gameMap.vehicles().forEach(function(vehicle) {
 this._characterSprites.push(new Sprite_Character(vehicle));
 }, this);
 $gamePlayer.followers().reverseEach(function(follower) {
 this._characterSprites.push(new Sprite_Character(follower));
 }, this);
 this._characterSprites.push(new Sprite_Character($gamePlayer));
 for (var i = 0; i < this._characterSprites.length; i++) {
 this._tilemap.addChild(this._characterSprites[i]);
 }
 };
 
 Spriteset_Map.prototype.createOverlayParallax = function() {
 this._overlayParallax = new TilingSprite();
 this._overlayParallax.move(0, 0, Graphics.width, Graphics.height);
 this._baseSprite.addChild(this._overlayParallax);
 };
 
 Spriteset_Map.prototype.createOverlayLight = function() {
 this._overlayLight = new TilingSprite();
 this._overlayLight.move(0, 0, Graphics.width, Graphics.height);
 this._baseSprite.addChild(this._overlayLight);
 };
 
 Spriteset_Map.prototype.updateOverlayGround = function() {
 var gndSwitch = $gameSwitches.value(groundSwitch);
 if (gndSwitch) {
 var groundIndex = $gameVariables.value(groundVariable);
 if (this._overlayGroundName !== 'ground' + $gameMap.mapId() + '-' + groundIndex) {
 this._overlayGroundName = 'ground' + $gameMap.mapId() + '-' + groundIndex;
 this._overlayGround.bitmap = ImageManager.loadOverlay(this._overlayGroundName);
 }
 if (this._overlayGround.bitmap) {
 this._overlayGround.origin.x = $gameMap.displayX() * $gameMap.tileWidth();
 this._overlayGround.origin.y = $gameMap.displayY() * $gameMap.tileHeight();
 }
 }
 else {
 if (this._overlayGroundName !== '') {
 this._overlayGroundName = '';
 this._overlayGround.bitmap = ImageManager.loadEmptyBitmap();
 }
 }
 };
 
 Spriteset_Map.prototype.updateOverlayParallax = function() {
 var parSwitch = $gameSwitches.value(parallaxSwitch);
 if (parSwitch) {
 var parIndex = $gameVariables.value(parallaxVariable);
 if (this._overlayParallaxName !== 'par' + $gameMap.mapId() + '-' + parIndex) {
 this._overlayParallaxName = 'par' + $gameMap.mapId() + '-' + parIndex;
 this._overlayParallax.bitmap = ImageManager.loadOverlay(this._overlayParallaxName);
 }
 if (this._overlayParallax.bitmap) {
 this._overlayParallax.origin.x = $gameMap.displayX() * $gameMap.tileWidth();
 this._overlayParallax.origin.y = $gameMap.displayY() * $gameMap.tileHeight();
 }
 }
 else {
 if (this._overlayParallaxName !== '') {
 this._overlayParallaxName = '';
 this._overlayParallax.bitmap = ImageManager.loadEmptyBitmap();
 }
 }
 };
 
 Spriteset_Map.prototype.updateOverlayLight = function() {
 var liSwitch = $gameSwitches.value(lightSwitch);
 if (liSwitch) {
 var lightIndex = $gameVariables.value(lightVariable);
 if (this._overlayLightName !== 'light' + $gameMap.mapId() + '-' + lightIndex) {
 this._overlayLightName = 'light' + $gameMap.mapId() + '-' + lightIndex;
 this._overlayLight.bitmap = ImageManager.loadOverlay(this._overlayLightName);
 }
 if (this._overlayLight.bitmap) {
 this._overlayLight.origin.x = $gameMap.displayX() * $gameMap.tileWidth();
 this._overlayLight.origin.y = $gameMap.displayY() * $gameMap.tileHeight();
 }
 }
 else {
 if (this._overlayLightName !== '') {
 this._overlayLightName = '';
 this._overlayLight.bitmap = ImageManager.loadEmptyBitmap();
 }
 }
 };
 })();

Merci pour votre aide