1     /**
2         Displays an animated Game Object
3         @author <a href="mailto:matthewcasperson@gmail.com">Matthew Casperson</a>
4         @class
5     */
6     function AnimatedGameObject()
7     {
8         /**
9             Defines the current frame that is to be rendered
10            @type Number
11         */
12        this.currentFrame = 0;
13        /**
14            Defines the frames per second of the animation
15            @type Number
16         */
17        this.timeBetweenFrames = 0;
18        /**
19            The number of individual frames held in the image
20            @type Number
21         */
22        /**
23            Time until the next frame
24            @type number
25         */
26        this.timeSinceLastFrame = 0;
27        /**
28            The width of each individual frame
29            @type Number
30         */
31        this.frameWidth = 0;
32
33        /**
34            Initialises this object
35            @param image The image to be displayed
36          @param x The position on the X axis
37            @param y The position on the Y axis
38          @param z The depth
39            @param frameCount The number of animation frames in the image
40            @param fps The frames per second to animate this object at
41        */
42        this.startupAnimatedGameObject = function(/**Image*/ image, /**Number*/ x, /**Number*/ y, /**Number*/ z, /**Number*/ frameCount, /**Number*/ fps)
43        {
44            if (frameCount <= 0) throw "framecount can not be <= 0";
45            if (fps <= 0) throw "fps can not be <= 0"
46
47            this.startupVisualGameObject(image, x, y, z);
48            this.currentFrame = 0;
49            this.frameCount = frameCount;
50            this.timeBetweenFrames = 1/fps;
51            this.timeSinceLastFrame = this.timeBetweenFrames;
52            this.frameWidth = this.image.width / this.frameCount;
53        }
54
55        /**
56            Draws this element to the back buffer
57            @param dt Time in seconds since the last frame
58          @param context The context to draw to
59          @param xScroll The global scrolling value of the x axis
60          @param yScroll The global scrolling value of the y axis
61        */
62        this.draw = function(/**Number*/ dt, /**CanvasRenderingContext2D*/ context, /**Number*/ xScroll, /**Number*/ yScroll)
63        {
64            var sourceX = this.frameWidth * this.currentFrame;
65            context.drawImage(this.image, sourceX, 0, this.frameWidth, this.image.height, this.x - xScroll, this.y - yScroll, this.frameWidth, this.image.height);
66
67            this.timeSinceLastFrame -= dt;
68            if (this.timeSinceLastFrame <= 0)
69            {
70               this.timeSinceLastFrame = this.timeBetweenFrames;
71               ++this.currentFrame;
72               this.currentFrame %= this.frameCount;
73            }
74        }
75    }
76
77    AnimatedGameObject.prototype = new VisualGameObject;