From 07f4f0487c1166faef8996545df35586cd3fe485 Mon Sep 17 00:00:00 2001
From: cha0s <git@cha0s.io>
Date: Sat, 13 Apr 2019 18:13:35 -0500
Subject: [PATCH] refactor: Camera::realOffset

---
 packages/topdown/camera.js | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/packages/topdown/camera.js b/packages/topdown/camera.js
index 526628b..b68d2d0 100644
--- a/packages/topdown/camera.js
+++ b/packages/topdown/camera.js
@@ -28,12 +28,16 @@ export class Camera extends decorate(class {}) {
 
   constructor() {
     super();
+    this._realOffset = [0, 0];
+    this.viewOrigin = [0, 0];
     this.on('areaSizeChanged', this.onAreaSizeChanged, this);
+    this.on('realPositionChanged', this.onRealPositionChanged, this);
     this.on('viewSizeChanged', this.onViewSizeChanged, this);
   }
 
   destroy() {
     this.off('areaSizeChanged', this.onAreaSizeChanged);
+    this.off('realPositionChanged', this.onRealPositionChanged, this);
     this.off('viewSizeChanged', this.onViewSizeChanged);
   }
 
@@ -41,8 +45,14 @@ export class Camera extends decorate(class {}) {
     this.position = this.position;
   }
 
+  onRealPositionChanged() {
+    this._realOffset = Vector.sub(this.realPosition, this.viewOrigin);
+  }
+
   onViewSizeChanged() {
     this.position = this.position;
+    this.viewOrigin = Vector.scale(this.viewSize, 0.5);
+    this._realOffset = Vector.sub(this.realPosition, this.viewOrigin);
   }
 
   get position() {
@@ -56,17 +66,21 @@ export class Camera extends decorate(class {}) {
     if (0 === Vector.area(this.viewSize)) {
       return super.position = position;
     }
-    const halfViewSize = Vector.scale(this.viewSize, 0.5);
+    const viewOrigin = this.viewOrigin;
     super.position = Vector.clamp(
       position,
-      halfViewSize,
-      Vector.sub(this.areaSize, halfViewSize)
+      viewOrigin,
+      Vector.sub(this.areaSize, viewOrigin)
     );
   }
 
+  get realOffset() {
+    return this._realOffset;
+  }
+
   get rectangle() {
     return Rectangle.compose(
-      Vector.sub(this.position, Vector.scale(this.viewSize, 0.5)),
+      Vector.sub(this.position, this.viewOrigin),
       this.viewSize,
     );
   }