From ec56fe7dea7e909397fee5b284a7e76f7b949599 Mon Sep 17 00:00:00 2001
From: Nathan Kunicki <me@nathankunicki.com>
Date: Sun, 27 Mar 2016 15:46:06 +0100
Subject: [PATCH] Added rotation support

---
 src/classes/entity.js | 18 ++++++++++++++----
 src/classes/rect.js   | 27 +++++++++++++++++++++++++--
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/src/classes/entity.js b/src/classes/entity.js
index 6fed1fe..8c1fc61 100644
--- a/src/classes/entity.js
+++ b/src/classes/entity.js
@@ -20,6 +20,7 @@ class Entity {
         this.velocity = new Vector2D(0, 0);
         this.acceleration = new Vector2D(0, 0);
         this.size = new Vector2D(0, 0);
+        this.rotation = 0;
 
         this.fields = [];
 
@@ -27,7 +28,8 @@ class Entity {
         this.children = [];
 
         this._relativePos = this.pos.clone();
-        this._lastCalculated = 0;
+        this._lastRelativePosCalculated = 0;
+        this._lastRelativeSizeCalculated = 0;
         this._game = null;
         this._parent = null;
 
@@ -60,11 +62,19 @@ class Entity {
     }
 
 
+    /**
+     * Returns the absolute x (Left) position relative to the entities parent tree
+     * @returns {number} x - x (Left) position relative to the entities parent tree
+     */
     get relativeLeft () {
         return this._calculateRelativePos().x;
     }
 
 
+    /**
+     * Returns the absolute y (Top) position relative to the entities parent tree
+     * @returns {number} y - y (Top) position relative to the entities parent tree
+     */
     get relativeTop () {
         return this._calculateRelativePos().y;
     }
@@ -94,7 +104,7 @@ class Entity {
     set height (height) {
         return this.size.y = height;
     }
-
+    
 
     /**
      * Set the velocity of the entity
@@ -193,7 +203,7 @@ class Entity {
 
         // When rendering, the draw calls should use this._relativePos rather than this.pos in order for the position to be correct.
 
-        if (this._game && this._lastCalculated < this._game.frameCounter) {
+        if (this._game && this._lastRelativePosCalculated < this._game.frameCounter) {
 
             if (this._parent) {
 
@@ -205,7 +215,7 @@ class Entity {
                 this._relativePos.y = this.pos.y;
             }
 
-            this._lastCalculated = this._game.frameCounter;
+            this._lastRelativePosCalculated = this._game.frameCounter;
 
         }
 
diff --git a/src/classes/rect.js b/src/classes/rect.js
index 9c2cd33..ec5db68 100644
--- a/src/classes/rect.js
+++ b/src/classes/rect.js
@@ -49,8 +49,31 @@ class Rect extends Entity {
 
         if (this._game) {
 
-            this._game.context.fillStyle = this.color.toString();
-            this._game.context.fillRect(this._scaleForLeft(this.relativeLeft), this._scaleForTop(this.relativeTop), this._scaleForWidth(this.width), this._scaleForHeight(this.height));
+            let left = this._scaleForLeft(this.relativeLeft),
+                top = this._scaleForTop(this.relativeTop),
+                width = this._scaleForWidth(this.width),
+                height = this._scaleForHeight(this.height),
+                ctx = this._game.context;
+
+            let xRot = left + (width / 2),
+                yRot = top + (height / 2);
+
+            if (this.rotation > 0) {
+                // Rotate the canvas based on the central point of this entity
+                ctx.translate(xRot, yRot);
+                ctx.rotate(this.rotation * Math.PI / 180);
+                ctx.translate(-xRot, -yRot);
+            }
+
+            ctx.fillStyle = this.color.toString();
+            ctx.fillRect(left, top, width, height);
+
+            if (this.rotation > 0) {
+                // Rotate back after drawing
+                ctx.translate(xRot, yRot);
+                ctx.rotate(-(this.rotation * Math.PI / 180));
+                ctx.translate(-xRot, -yRot);
+            }
 
             return true;