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Topic 11: Motion Tracking Part III

Topic 11: Motion Tracking Part III. Button Click. Usually done via mouse click. Button Click. Can we click digital buttons by our fingers directly ? Answer: Yes! Through motion Of course, you can also rely on touch sensors Need extra hardware. Today’s Examples.

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Topic 11: Motion Tracking Part III

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  1. Topic 11: Motion Tracking Part III SCM-CityU

  2. Button Click • Usually done via mouse click SCM-CityU

  3. Button Click • Can we click digital buttons by our fingers directly? • Answer: Yes! • Through motion • Of course, you canalso rely on touchsensors • Need extra hardware SCM-CityU

  4. Today’s Examples • Motion-driven button interaction SCM-CityU

  5. Today’s Examples • Motion-driven button interaction SCM-CityU

  6. Motion Tracking Library • In cityu.scm package (developed by Hongbo Fu) • Webcam class • An easy-to-use wrapper for webcam access • MotionTracker class • Main class for motion tracking • MotionTrackerButtonclass • Use motion to trigger button clicking SCM-CityU

  7. Key Idea • Analyze motion over a button on the stage • If motion is detected over it, dispatch OVER event • Cf. MouseEvent.MOUSE_OVER • If motion continuously exists for a while, dispatch CLICKED event • Cf. MouseEvent.MOUSE_DOWN • To avoid undesired clicks after dispatching CLICKED event, clicking is disabled for a short period (say 2 sec) • If clicking is re-enabled, dispatch CLICKABLE event • Cf. MouseEvent.MOUSE_UP SCM-CityU

  8. MotionTrackerButton Class • To create a motion-driven button, you need • Step 1: create some display object (e.g., btn) on stage • By either design tool or ActionScript programming • Step 2: create a MotionTrackerButton object and associate it with btn • Step 3: add event listeners for motionBtn • MotionTrackerButton.OVER MotionTrackerButton.CLICKED MotionTrackerButton.CLICKABLE varmotionBtn:MotionTrackerButton= newMotionTrackerButton(webcam,btn); SCM-CityU

  9. Step 1: Create Display Object • Draw some shape on stage • Convert it to symbol • Assign an instance name (e.g., btn) SCM-CityU

  10. Review: Instance Name vs Class Name • Symbol instance name (cf. variable in AS) • Use this when you want to directly access this symbol instance in AS (e.g., btn.x = 20;) • Symbol class name (cf. complexdata type in AS) • Use this when you want to dynamically create (possibly many) symbol instances in AS • E.g., var btn2: MyButton = new MyButton(); SCM-CityU

  11. Step 2: Create MotionTrackerButton Object • Before adding a MotionTrackerButton object, we need to initialize a Webcamobject • We don’t need to explicitly create a MotionTrackerobject, since it is automatically generated for the associated button importcityu.scm.Webcam;// import Webcam class varwebcam:Webcam=new Webcam(640,480);webcam.addEventListener(Webcam.READY,onCameraReady); functiononCameraReady(e:Event):void{ addChild(webcam); // to avoid occlusion of stage objects by webcam webcam.sendToBack(); webcam.alpha=0.4; } SCM-CityU

  12. Step 2: Create MotionTrackerButton Object • First import MotionTrackerButtonclass • Then create a button with motion control • 3rd parameter: amount of motion needed to activate clicking • How easy a button can be clicked • 4th parameter: time (in milliseconds) needed to re-enable clicing after dispatching CLICKED event • How oftena button can be clicked importcityu.scm.MotionTrackerButton; varmotionBtn:MotionTrackerButton= newMotionTrackerButton(webcam,btn,10,500); SCM-CityU

  13. Step 2: Create MotionTrackerButton Object • Motion detection is clipped to the button area only • To see tracking visualization, make the button a bit transparent SCM-CityU

  14. Step 3: Add Event Listeners • Event types • MotionTrackerButton.OVER • MotionTrackerButton.CLICKED • MotionTrackerButton.CLICKABLE motionBtn.addEventListener(MotionTrackerButton.OVER, onButtonOver); motionBtn.addEventListener(MotionTrackerButton.CLICKED, onButtonClick); motionBtn.addEventListener(MotionTrackerButton.CLICKABLE, onButtonClickableAgain); function onButtonClick(e:Event):void{ trace("button clicked"); } SCM-CityU

  15. Add More Visual Effects • Idea: create multiple frames for the button and go to certain frame when a certain condition is satisfied • The button in our example is just a movie clip • Review: MovieClip’s properties and methods (ref) • Note: we can access a frame by either frame number or label • Properties • currentFrame: int • currentLabel: String • totalFrames: int • Methods • stop(), play() • nextFrame(), prevFrame() • gotoAndStop(frame) • frame is a number or string • gotoAndPlay(frame) SCM-CityU

  16. Add More Visual Effects • Modify button symbol to have two key frames • Frame 1 • Use the original shape • Frame label: up • Frame 2 • Add some shadow filter • Frame label: down SCM-CityU

  17. Class Exercise • Task 1: when button is clicked by motion • If btn’s current frame label is “up”, go to frame “down” • If btn’s current frame label is “down”, go to frame “up” • Tips • Add code in onButtonClick • Use currentLabel, gotoAndStop SCM-CityU

  18. Class Exercise • Task 2: play with different values for 3rd and 4th parametersof MotionTrackerButton. • 3rd parameter: how easy a button can be clicked • 4th parameter: how often a button can be clicked • Compare • MotionTrackerButton(webcam, btn, 1, 500); • MotionTrackerButton(webcam, btn, 20, 500); • Compare • MotionTrackerButton(webcam, btn, 5, 50); • MotionTrackerButton(webcam, btn, 5, 2000); SCM-CityU

  19. Example: Piano with Motion Control • How to interact multiple MotionTrackerButton objects? SCM-CityU

  20. Class Exercise • Open MotionTracker-Piano-Skeleton.fla and insert a new symbol • Frame 1 of this new symbol • Frame 2 of this new symbol • No AS code needed for this frame SCM-CityU

  21. Class Exercise • Create 7 instances of the new symbol on stage • Instance names from left to right: key1, key2, key3, key4, key5, key6, key7 • Alternatively, you can create those instances in AS using for loop SCM-CityU

  22. Music Notes • We use an array to store music notes var notes:Array=[new S1(),new S2(), new S3(),new S4(), new S5(),new S6(), new S7()]; SCM-CityU

  23. Create Motion Buttons • We use arrays to store both piano keys and their corresponding motion buttons • Corresponding key and motion button have same index // a list of motion buttons. e.g., keysMB[0] is for keys[0] var keysMB:Array=newArray(); var keys:Array=[key1, key2, key3, key4, key5, key6, key7]; for(var i:uint =0; i < keys.length; i++){ keysMB.push(newMotionTrackerButton(webcam,keys[i],5,500)); } SCM-CityU

  24. Event Listeners for(var i:uint =0; i < keys.length; i++){ // motion-driven keysMB[i].addEventListener(MotionTrackerButton.CLICKED, onKeyPressed); keysMB[i].addEventListener(MotionTrackerButton.CLICKABLE, onKeyReleased); } functiononKeyPressed(e:Event):void{ for(var i:uint =0; i < keys.length; i++){ if(keysMB[i]== e.target){ trace("index of pressed key", i); } } } SCM-CityU

  25. Extension to Other Instruments SCM-CityU

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