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 that conatins that animation film strip
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            return this;
55        }
56        /**
57            Sets the animation to be played
58            @param image        The image that conatins that animation film strip
59            @param frameCount   The number of animation frames in the image
60            @param fps          The frames per second to animate this object at
61        */
62        this.setAnimation = function(/**Image*/ image, /**Number*/ frameCount, /**Number*/ fps)
63        {
64            if (frameCount <= 0) throw "framecount can not be <= 0";
65            if (fps <= 0) throw "fps can not be <= 0"
66
67            this.image = image;
68            this.currentFrame = 0;
69            this.frameCount = frameCount;
70            this.timeBetweenFrames = 1/fps;
71            this.timeSinceLastFrame = this.timeBetweenFrames;
72            this.frameWidth = this.image.width / this.frameCount;
73        }
74
75        /**
76            Draws this element to the back buffer
77            @param dt Time in seconds since the last frame
78          @param context The context to draw to
79          @param xScroll The global scrolling value of the x axis
80          @param yScroll The global scrolling value of the y axis
81        */
82        this.draw = function(/**Number*/ dt, /**CanvasRenderingContext2D*/ context, /**Number*/ xScroll, /**Number*/ yScroll)
83        {
84            var sourceX = this.frameWidth * this.currentFrame;
85            context.drawImage(this.image, sourceX, 0, this.frameWidth, this.image.height, this.x - xScroll, this.y - yScroll, this.frameWidth, this.image.height);
86
87            this.timeSinceLastFrame -= dt;
88            if (this.timeSinceLastFrame <= 0)
89            {
90               this.timeSinceLastFrame = this.timeBetweenFrames;
91               ++this.currentFrame;
92               this.currentFrame %= this.frameCount;
93            }
94        }
95    }
96
97    AnimatedGameObject.prototype = new VisualGameObject;