HTML5 Canvas

Transcript HTML5 Canvas

HTML5 Canvas Essentials Steve Fulton & Jeff Fulton

Something Cool The Canvas Can Do Demo

Easily takes a hidden video from the HTML page, displays it multiple times, moves each copy Independently it around the screen, while playing it.

Who Are We?

• • • • • • • Steve and Jeff Fulton (twins) Web developers since 1995 Worked for Mattel Toys until 2010/2011 on all of their web properties (Barbie, Hot Wheels, etc.) including games apps. MMOs Have Built over 200 games in Flash, HTML5, Mobile Authored of The Essential Guide To Flash Games book in 2010 Authored of HTML 5 Canvas in 2011 Now both working in independently on mobile, web, multi-player HTML5, Flash, Corona games and apps

• • •

Why Move From Flash to The Canvas? Our Story

Finished Essential guide To Flash Games in March 2010 Steve Jobs refused Flash on the iOS just days later Wanted to find a technology that would be truly multi-platform and not be subject to whims of CEOs

• • •

Why Move From Flash to The Canvas? Our Story

Easy Tools: a web browser, text editor and JavaScript was all that was required.

The HTML5 Canvas allowed for a bitmapped graphics, much Flash’s bitmapped canvas.

Our specific Type Of Game Development translates well (tile sheets, bitmaps)

What is the HTML5 Canvas?

• The HTML5 Canvas is an Immediate Mode bit mapped area of the screen that can be manipulated with JavaScript and CSS.

What Is Immediate Mode?

• Immediate Mode refers to the way the canvas renders pixels on the screen. The HTML5 Canvas completely redraws the bitmapped screen on every frame using Canvas API calls from JavaScript. As a programmer, your job is to set-up the screen display before each frame is rendered.

What Is Retained Mode?

• Flash, Silverlight, and DOM

manipulation techniques use Retained Mode. In Retained Mode a list of individual display objects is stored and manipulated.

HTML5 Canvas Support

• Support for the Canvas is growing. Right now we think the best browser support goes in this order: – Chrome – Safari (Mac and iOS 5) – I.E. 9 (surprised?) – Firefox – Opera

HTML5 Canvas Support : Mobile

• • • • Support and performance has increased in 2011 iOS 5 improved performance greatly Current Android performance is poor to good depending on the device Windows 8/Metro is supposedly built to handle HTML5 Canvas, and we believe that is the reason I.E. 9 ranks so highly right now

Canvas And The DOM

• • • • DOM : Document Object Model Canvas is a DOM Object Accessible via the 2D Canvas context Has both it’s own properties and CSS properties

What Can The Canvas Be Used for?

• Nearly anything that Flash notorious for: – Banner Ads – Animated Landing Pages – Web Games – Video

Canvas Banner Ad

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Demo

Should be put in an PNG sequence but could easily be dynamically generated Canvas text</p> <a id="p15" href="#"></a> <p>•</p> <h3>Demo Animated Landing Pages</h3> <a id="p16" href="#"></a> <h3>Web Advergame</h3> <p>• • • •</p> <h3>Demo</h3> <p>Targets all HTML5 devices Mobile/Web Touch Controls Only</p> <a id="p17" href="#"></a> <h3>Video</h3> <p>• •</p> <h3>Demo</h3> <p>Video played • Directly on Canvas Can Create frame counter To trigger events</p> <a id="p18" href="#"></a> <h3>What Is It Not Good For?</h3> <p>• Some of Flash’s core competencies : – Heavy, time-line based key-frame animation – Vector motion graphics – Secure, monetizable video – Code/asset encapsulation – Advanced Audio applications – Hard Core Games (at the moment)</p> <a id="p19" href="#"></a> <h3>Why Canvas Instead Of <div>?</h3> <p>• • • • • Not an either/or situation Use the best of all the “HTML5” technologies For Flash AS3 developers, many algorithms translates easily to JavaScript + Canvas We have already seen Canvas performance improve as browsers improve (iOS5) GPUs are made to accelerate the display of the bitmaps and 3D images (WebGL) the Canvas can create</p> <a id="p20" href="#"></a> <h3>A Quick Guide To Canvas Development</h3> <p>• Next we will describe the Canvas element, its’ properties and methods, then show how to create a simple Canvas application</p> <a id="p21" href="#"></a> <h3>HTML5 Canvas Properties</h3> <p>• • • Canvas Has Three Properties: width height id Width and height read/write which means you can resize the Canvas on the fly </p> <a id="p22" href="#"></a> <h3>HTML5 Canvas Methods</h3> <p>• • getContext() : You need the context to draw anything on the Canvas. We will see this shortly toDataUrl() : Outputs the bitmapped data of the Canvas to a string (can be used to create a screenshot)</p> <a id="p23" href="#"></a> <h3>HTML5 Canvas And CSS</h3> <p>• • • CSS can be used in conjunction with Canvas object itself. However, individual drawings on the Canvas cannot be manipulated with CSS Example: you can scale the Canvas using CSS style=”width: 400px; height:400px” Does not resize but instead scales (like setting width ad height for a Flash embed)</p> <a id="p24" href="#"></a> <h3>Basic HTML5 Page</h3> <p>• Simplified greatly from HTML4 <!doctype html> <html lang="en"></p> <a id="p25" href="#"></a> <h3>Basics HTML5 Page</h3> <p><b>CH1EX1 – Basic HTML Page</b></p> <p><!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Ch1Ex1: Basic Hello World HTML Page</title> </head> <body> Hello World!</p> <p></body> </html> CH1EX1.html</p> <a id="p26" href="#"></a> <p>•</p> <h3>Demo Canvas Hello World</h3> <a id="p27" href="#"></a> <h3>Canvas Hello World</h3> <p>In the <i><body> </i>section of the HTML page, you add a <i><canvas> </i>tag using code like the following: <canvas id="canvasOne" width="500" height="300"> Your browser does not support the HTML 5 Canvas. </canvas> </p> <a id="p28" href="#"></a> <h3>Canvas Hello World</h3> <p>• • • Setting up your Canvas app structure is very important to get started.</p> <p>The next section is code heavy, but we believe it is important to get a code structure down that you can use for your apps Our structure is not the only way to do it</p> <a id="p29" href="#"></a> <h3>Canvas Hello World</h3> <p>In the <HEAD> of your HTML page, start adding JavaScript <head> <script type="text/javascript"></p> <p><b>//Canvas Code Goes Here</b></p> <p></script> </head></p> <a id="p30" href="#"></a> <h3>Canvas Hello World</h3> <p>• •</p> <p><b>Testing for the Canvas Support</b></p> <p>We use modernizr.js to test for the Canvas support. Get it here: http://www.modernizr.com/ <script src="modernizr.js"></script> <script type="text/javascript"> function canvasSupport () { return Modernizr.canvas; } </script></p> <a id="p31" href="#"></a> <h3>Canvas Hello World</h3> <p>We need to wait For the Browser Window To Finish Loading so we can be sure all of the JavaScript is available.</p> <p>window.addEventListener("load", eventWindowLoaded, false); </p> <a id="p32" href="#"></a> <h3>Canvas Hello World</h3> <p>After window loads, call start application: Encapsulate Canvas code in it’s own function object: function eventWindowLoaded () { canvasApp(); }</p> <a id="p33" href="#"></a> <h3>Basic Structure of Canvas Object</h3> <p>• • • • Test For Canvas Support Get a reference to the Canvas object on the HTML page Get reference to the Canvas 2D context from the Canvas object Create a stub function used to draw onto the Canvas</p> <a id="p34" href="#"></a> <h3>Canvas Hello World</h3> <p>Basic Structure Of Canvas App function canvasApp () { if (!canvasSupport()) { return; } var theCanvas = document.getElementById("canvasOne"); var context = theCanvas.getContext("2d"); function draw() {</p> <p><b>//all the cool drawing stuff goes here</b></p> <p>} draw() }</p> <a id="p35" href="#"></a> <h3>Canvas Hello World</h3> <p>• • • • Draw filled box as the background Draw “stroke” box as the border We need the Canvas context to draw anything Since we are drawing in immediate mode, we set Canvas context properties one at a time to draw different objects.</p> <a id="p36" href="#"></a> <h3>Canvas Hello World</h3> <p><b>Background: </b>yellow box, black outline context.fillStyle = "#ffffaa"; context.fillRect(0, 0, 500, 300); context.strokeStyle = "#000000"; context.strokeRect(5, 5, 490, 290);</p> <a id="p37" href="#"></a> <h3>Canvas Hello World</h3> <p>• • • The background is drawn first. Since there is no concept of a “display list” in immediate mode, we need to make sure to draw things in the order we want them stacked (i.e. background first, text second) Advanced: globalCompositeOperation property of the context can be manipulated for layering purposes</p> <a id="p38" href="#"></a> <h3>Canvas Hello World</h3> <p><b>Adding Text: </b>After drawing the boxes<b>, </b> context.fillStyle</p> <p>is updated with a new color. Think of this like a hand (context) with a crayon. There is only one hand to draw with, so you swap out the crayon (fillStyle) and draw the text.</p> <p>context.fillStyle</p> <p>context.font</p> <p>= "#000000"; = "20px _sans"; context.fillText("Hello world!",195,80 );</p> <a id="p39" href="#"></a> <h3>Canvas Hello World</h3> <p>• • • Adding an image: Use JavaScript Image() object to load and reference an image Use context.drawImage(imageRef, x,y) to draw it on the Canvas</p> <a id="p40" href="#"></a> <h3>Canvas Hello World</h3> <p><b>Adding An Image:</b></p> <p>var helloWorldImage = new Image(); helloWorldImage.onload = function () { context.drawImage(helloWorldImage, 160, 130); } helloWorldImage.src = "helloworld.gif";</p> <a id="p41" href="#"></a> <h3>Canvas Hello World Redux</h3> <p>•</p> <h3>Demo</h3> <p>(again)</p> <a id="p42" href="#"></a> <h3>Text Mangler</h3> <a id="p43" href="#"></a> <h3>How It Works: Interacting with HTML</h3> <p>• • • Standard HTML <form> elements JavaScript “change” events to call functions Draw() function called to re-render</p> <a id="p44" href="#"></a> <h3>Text Mangler</h3> <p>• • • • • • • • Demo (apply to more than text) Text : context.font = “64px italic bold _sans” Resize : (canvas.width, canvas.height) Scale : style=”width:xxx; height:xxx;” (warning!) Alpha : (context.globalAlpha) Gradient Fills (context.createLinearGradient()) Shadows : (context.shadowColor ) Screen Shot: canvas.toDataUrl()</p> <a id="p45" href="#"></a> <h3>Simple Animation</h3> <p>• • To animate you need to call a function on an interval to update the Canvas Drawing objects (circle, boxes), bitmapped images, and video all need to be updated on every frame to animate/play</p> <a id="p46" href="#"></a> <h3>Simple Animation</h3> <p>• • Let’s use a tile sheet of a tank and animate it driving across the screen.</p> <p>This uses a PNG file set as a tile sheet, and interval, and some code change the position of the tank on the Canvas</p> <a id="p47" href="#"></a> <h3>Simple Animation</h3> <p>• • Let’s use a tile sheet of a tank and animate it driving across the screen.</p> <p>This uses a PNG file set as a tile sheet, and interval, and some code change the position of the tank on the Canvas</p> <a id="p48" href="#"></a> <h3>Simple Animation</h3> <p>• The Tile Sheet looks like this</p> <a id="p49" href="#"></a> <p>Demo</p> <h3>Simple Animation</h3> <a id="p50" href="#"></a> <h3>Simple Animation</h3> <p>Steps: 1.</p> <p>First we load in the tile sheet var tileSheet=new Image(); tileSheet.addEventListener('load', eventShipLoaded false); tileSheet.src="tanks_sheet.png"; 2. Next we set up an array of fames from the tile sheet for the tank track var animationFrames=[1,2,3,4,5,6,7,8]; 3. We create an index to use to specify which frame we are to draw var frameIndex=0;</p> <a id="p51" href="#"></a> <h3>Simple Animation</h3> <p>4. We set up the rotation, x,y, dx, and dy properties for the tank var rotation=90; var x=50; var y=50; var dx=1; var dy=0 ; 5. We create a listener function for the tile sheet load function eventShipLoaded() { startUp(); }</p> <a id="p52" href="#"></a> <h3>Simple Animation</h3> <p>6. The startUp() function will set up an interval to call the draw function every 100 milliseconds function startUp(){ setInterval(drawScreen, 100 ); } 7. The draw() is code heavy. It will re-draw the background, then it will update the x and y coordinates of the tank based on the dx and y values. Next, it will then save the current context, draw the current frame of the tank and restore the current context. Finally, it will update the frameIndex for the tank display. We are rotating the tank 90 degrees, so we will also be adding in a rotation and translation transformation.</p> <a id="p53" href="#"></a> <h3>Simple Animation</h3> <p>function drawScreen() { x=x+dx; y=y+dy; //draw a background so we can wee the Canvas edges context.fillStyle="#aaaaaa"; context.fillRect(0,0,500,500); context.save(); context.setTransform(1,0,0,1,0,0) var angleInRadians =rotation * Math.PI / 180; context.translate(x+16, y+16) context.rotate(angleInRadians);</p> <a id="p54" href="#"></a> <h3>Simple Animation</h3> <p>var sourceX=Math.floor(animationFrames[frameIndex] % 8) *32; var sourceY=Math.floor(animationFrames[frameIndex] / 8) *32; context.drawImage(tileSheet, sourceX, sourceY,32,32,-16, 16,32,32); context.restore(); } frameIndex++; if (frameIndex ==animationFrames.length) { frameIndex=0; }</p> <a id="p55" href="#"></a> <h3>Simple Animation Demo Again</h3> <p>Demo</p> <a id="p56" href="#"></a> <h3>Draw With Paths</h3> <p>• • The easiest method to draw on the Canvas is to create a series of paths (like vector drawing) to depict our shapes. We will use the beginPath(), moveTo(), lineTo(), stroke(), and closePath() methods to create our shapes.</p> <a id="p57" href="#"></a> <h3>Draw With Paths</h3> <p>context.strokeStyle="#ff0000"; context.beginPath(); context.moveTo(100,100); context.lineTo(150,100); context.lineTo(150,150); context.lineTo(100,150); context.lineTo(100,100); context.stroke(); context.closePath();</p> <a id="p58" href="#"></a> <p>Demo</p> <h3>Draw With Paths</h3> <a id="p59" href="#"></a> <h3>Rotation Transformation (Jeff)</h3> <p>• • • We can easily rotate the drawn path by applying a simple rotation transformation.</p> <p>First we reset the Canvas transformation matrix it s “identity” or reset value: context.setTransform(1,0,0,1,0,0); Next, we set the angle we want the next path to be drawn in with a radian value: context.rotate(45* Math.PI / 180);</p> <a id="p60" href="#"></a> <h3>A Bit More Advanced</h3> <p>• Because the Canvas is an immediate mode drawing surface, some things are vastly more complicated than creating them in something like Flash • Example : Rotating an object on the Canvas</p> <a id="p61" href="#"></a> <h3>Canvas State</h3> <p>• • • The current contents of the Canvas can be stored in a stack.</p> <p>Context.save() will save the current state Context.restore() will restore the previous Canvas state.</p> <p>Why?</p> <a id="p62" href="#"></a> <h3>Rotation Transformation</h3> <p>• • • We can easily rotate the drawn path by applying a simple rotation transformation.</p> <p>First we reset the Canvas transformation matrix it s “identity” or reset value: context.setTransform(1,0,0,1,0,0); Next, we set the angle we want the next path to be drawn in with a radian value: context.rotate(45* Math.PI / 180);</p> <a id="p63" href="#"></a> <h3>Rotation Transformation </h3> <p>context.setTransform(1,0,0,1,0,0); context.rotate(45* Math.PI / 180); context.strokeStyle="#ff0000"; context.beginPath(); context.moveTo(100,100); context.lineTo(150,100); context.lineTo(150,150); context.lineTo(100,150); context.lineTo(100,100); context.stroke(); context.closePath();</p> <a id="p64" href="#"></a> <p>Demo</p> <h3>Rotation Transformation </h3> <p>What happened? The square was rotated, but the top left corner of the Canvas was used at the origin for the rotation. Let’s fix that with a translation transformation.</p> <a id="p65" href="#"></a> <h3>Rotation Transformation </h3> <p>• • • • To rotate an object around its own center point, we must: Translate the Canvas to the center of our object.</p> <p>Draw our object 0,0 is it’s current top left corner.</p> <p>If we want a 50 x 50 square that starts at 100,100, then we must do this translation: context.translate(125,125)</p> <a id="p66" href="#"></a> <h3>Rotation Transformation </h3> <p>• • • • To rotate an object around its own center point, we must: Translate the Canvas to the center of our object.</p> <p>Draw our object at 0,0 as is now the current top left corner.</p> <p>If we want a 50 x 50 square that starts at 100,100, then we must do this translation: context.translate(125,125)</p> <a id="p67" href="#"></a> <h3>Rotation Transformation </h3> <p>context.setTransform(1,0,0,1,0,0); context.translate(125,125) context.rotate(45* Math.PI / 180); context.strokeStyle="#ff0000"; context.beginPath(); context.moveTo(0,0); context.lineTo(50,0); context.lineTo(50,50); context.lineTo(0,50); context.lineTo(0,0); context.stroke(); context.closePath();</p> <a id="p68" href="#"></a> <h3>Rotation Transformation </h3> <p>Demo What happened? We rotated the object around it’s center rather than the top-left corner of the canvas.</p> <a id="p69" href="#"></a> <h3>Canvas State</h3> <p>• • The current Canvas state (transformation Matrix and Clipping region and style attributes) can be saved with context.save() and retrieved with context.restore() . The current path and current bitmap data on the Canvas are not saved.</p> <a id="p70" href="#"></a> <h3>Canvas State </h3> <p>• This is useful with transformations (especially the translations seen previously). Because a translation effects the entire coordinate system of the Canvas, simply resetting to the identity (default) might not always get the results you want. The best option is to save() before the operation and restore() after.</p> <a id="p71" href="#"></a> <h3>Canvas State</h3> <p>This allows us to set the coordinate systems, all translations, all stoke and fill attributes, etc back to what they were before the save() operation. Here is an example:</p> <a id="p72" href="#"></a> <h3>Canvas State Example</h3> <p>• • • • • • • Set the fillStyle to gray Draw a filled box Add an image Save state Draw a rotated red square Restore Draw a yellow box that is not rotated</p> <a id="p73" href="#"></a> <h3>Canvas State </h3> <p>context.fillStyle="#dddddd"; context.fillRect(0,0,500,500); var helloWorldImage = new Image(); helloWorldImage.onload = function () { context.drawImage(helloWorldImage, 160, 130); } helloWorldImage.src = "helloworld.gif"; context.strokeStyle="#ffff00";</p> <a id="p74" href="#"></a> <h3>Canvas State (Jeff)</h3> <p>context.save() context.translate(125,125) context.rotate(45* Math.PI / 180); context.strokeStyle="#ff0000"; context.beginPath(); context.moveTo(0,0); context.lineTo(50,0); context.lineTo(50,50); context.lineTo(0,50); context.lineTo(0,0); context.stroke(); context.closePath(); context.restore();</p> <a id="p75" href="#"></a> <h3>Canvas State</h3> <p>context.save() context.translate(125,125) context.rotate(45* Math.PI / 180); context.strokeStyle="#ff0000"; context.beginPath(); context.moveTo(0,0); context.lineTo(50,0); context.lineTo(50,50); context.lineTo(0,50); context.lineTo(0,0); context.stroke(); context.closePath(); context.restore();</p> <a id="p76" href="#"></a> <h3>Canvas State</h3> <p>//new path context.beginPath(); context.moveTo(50,50); context.lineTo(100,50); context.lineTo(100,100); context.lineTo(50,100); context.lineTo(50,50); context.stroke(); context.closePath();</p> <a id="p77" href="#"></a> <h3>Canvas State</h3> <p>`</p> <a id="p78" href="#"></a> <h3>What About Adobe?</h3> <p>• • • • Adobe Edge does not use Canvas (yet) phoneGap purchase should lead to packaging of mobile apps with Adobe tools Abandoning Flash on mobile leaves the door open for another bitmapped technology (i.e</p> <p>Canvas) to be the focus Flash-like tool for Canvas would be ideal</p> <a id="p79" href="#"></a> <h3>Future Of Flash vs. Canvas?</h3> <p>• • • • • SWF format’s days are probably numbered Flash IDE is still an unrivaled animation tool Flash .flv is still best option for secure video streams Air Packager is the future for games and apps created with Flash IDE and Flex. Within two years, HTML5 + Canvas will most likely rule the web page</p> <a id="p80" href="#"></a> <h3>Contact Us</h3> <p>• • •</p> <h3>http://www.8bitrocket.com</h3> <h3>info@8bitrocket.com</h3> <p>Twitter@8bitrocket</p> <a id="p81" href="#"></a> <h3>Power Of The Canvas</h3> <p>Steve Fulton & Jeff Fulton</p> <a id="p82" href="#"></a> <h3>Application Demos</h3> <p>• • Most (but not all) of the things that Flash was once used for can now be done on the Canvas.</p> <p>We specialize in retro style games, so these demos are heavily geared in that direction, but that does not mean they are the only types of apps and games you can make</p> <a id="p83" href="#"></a> <h3>Video Puzzle</h3> <p>• •</p> <h3>Demo</h3> <p>Slicing Up A Video Source</p> <a id="p84" href="#"></a> <h3>Video Puzzle</h3> <p>• Add video to Canvas videoElement = document.createElement("video"); videoElement.setAttribute("src", "muirbeach.webm"); videoElement.setAttribute("loop", "true");</p> <a id="p85" href="#"></a> <h3>Video Puzzle</h3> <p>• To cut a part of a video element and place it on the Canvas you would use code like this function draw() { … context.drawImage(videoElement, imageX, imageY, partWidth, partHeight, placeX, placeY, partWidth, partHeight); … }</p> <a id="p86" href="#"></a> <h3>Games : Ball Battle</h3> <p>• • • Demo Pool Ball Physics Took book demo and tried explore it as • a game Could be done with Box2d Physics library</p> <a id="p87" href="#"></a> <h3>Ball Battle</h3> <p>• • • • Pool Ball Physics Code adapted almost directly from a Flash project Difference is that with Flash when you set x,y properties, the objects are instantly updated (retained mode). With the Canvas you still need to draw them so code needed to be adapted to accommodate for it.</p> <p>Code is lengthy (will only show it)</p> <a id="p88" href="#"></a> <h3>Ball Battle</h3> <p>• } function collideBalls(ball1,ball2) { var dx = ball1.nextx - ball2.nextx; var dy = ball1.nexty - ball2.nexty; var collisionAngle = Math.atan2(dy, dx); var speed1 = Math.sqrt(ball1.velocityx * ball1.velocityx + ball1.velocityy * ball1.velocityy); var speed2 = Math.sqrt(ball2.velocityx * ball2.velocityx + ball2.velocityy * ball2.velocityy); var direction1 = Math.atan2(ball1.velocityy, ball1.velocityx); var direction2 = Math.atan2(ball2.velocityy, ball2.velocityx); var velocityx_1 = speed1 * Math.cos(direction1 - collisionAngle); var velocityy_1 = speed1 * Math.sin(direction1 - collisionAngle); var velocityx_2 = speed2 * Math.cos(direction2 - collisionAngle); var velocityy_2 = speed2 * Math.sin(direction2 - collisionAngle); var final_velocityx_1 = ((ball1.mass - ball2.mass) * velocityx_1 + (ball2.mass + ball2.mass) * velocityx_2)/(ball1.mass + ball2.mass); var final_velocityx_2 = ((ball1.mass + ball1.mass) * velocityx_1 + (ball2.mass - ball1.mass) * velocityx_2)/(ball1.mass + ball2.mass); var final_velocityy_1 = velocityy_1; var final_velocityy_2 = velocityy_2 ball1.velocityx = Math.cos(collisionAngle) * final_velocityx_1 + Math.cos(collisionAngle + Math.PI/2) * final_velocityy_1; ball1.velocityy = Math.sin(collisionAngle) * final_velocityx_1 + Math.sin(collisionAngle + Math.PI/2) * final_velocityy_1; ball2.velocityx = Math.cos(collisionAngle) * final_velocityx_2 + Math.cos(collisionAngle + Math.PI/2) * final_velocityy_2; ball2.velocityy = Math.sin(collisionAngle) * final_velocityx_2 + Math.sin(collisionAngle + Math.PI/2) * final_velocityy_2; ball1.nextx = (ball1.nextx += ball1.velocityx); ball1.nexty = (ball1.nexty += ball1.velocityy); ball2.nextx = (ball2.nextx += ball2.velocityx); ball2.nexty = (ball2.nexty += ball2.velocityy);</p> <a id="p89" href="#"></a> <h3>Ball Battle</h3> <p>• • Uses Circle To Circle Collision detection Requires that each ball object be set with x, y, radius, and preset nextX, nextY properties so we can test before balls overlap.</p> <a id="p90" href="#"></a> <h3>Ball Battle</h3> <p><b>Circle To Circle Collision Detection</b></p> <p>function hitTestCircle(ball1,ball2) { var retval = false; var dx = ball1.nextx - ball2.nextx; var dy = ball1.nexty - ball2.nexty; var distance = Math.sqrt(dx * dx + dy * dy); if (distance <= (ball1.radius + ball2.radius)) { retval = true; } return retval; }</p> <a id="p91" href="#"></a> <h3>Atari 2600 Fireworks</h3> <p>• • •</p> <h3>Demo</h3> <p>Particle pool Pool keeps the Numbers of active Object minimizes to Save memory</p> <a id="p92" href="#"></a> <h3>Fireworks Particle Pool</h3> <p>• Create an array to hold the particles and one to hold an unused pool of particle object var particlePool = new Array(); var particles = new Array(); var MAX_POOL_SIZE = 100;</p> <a id="p93" href="#"></a> <h3>Fireworks Particle Pool</h3> <p>•</p> <p><b>Take object from Pool or create a new one</b></p> <p>if (particlePool.length > 0) { } var tempParticle = particlePool.pop(); tempParticle.x = x; tempParticle.y = y; … … } else { particles.push({x:x,y:y,xunits:xunits,yunits:yunits, life:life,color:color,width:width,height:height,gravity:gr av,moves:0,alpha:1, maxLife:life});</p> <a id="p94" href="#"></a> <p>}</p> <h3>Fireworks Particle Pool</h3> <p><b>Add object back into pool</b></p> <p>if (particles[i].life <= 0 ) { if (particlePool.length < MAX_POOL_SIZE) { particlePool.push(particles.splice(i,1)); } else { particles.splice(i,1); }</p> <a id="p95" href="#"></a> <h3>Games: Brick Basher</h3> <p>• • • Demo Graphics switch (g) A test with Gradient Fills, • Shadows on many objects Performance issues with • Un-optimized code Be sure to test in multiple Browsers : Firefox Demo</p> <a id="p96" href="#"></a> <p>• •</p> <h3>Demo</h3> <p>Canvas CSS</p> <h3>Drag And Drop</h3> <a id="p97" href="#"></a> <h3>Drag And Drop</h3> <p><b>Listen for Canvas “mousemove” event:</b></p> <p>theCanvas.addEventListener("mousemove",onMou seMove, false);</p> <a id="p98" href="#"></a> <h3>Drag And Drop</h3> <p><b>Test To see if the mouse is over any of the objects:</b></p> <p>for (i=0; i< clickBlocks.length; i++) { var tp = clickBlocks[i]; if ( (mouseY >= tp.y) && (mouseY <= tp.y+tp.height) && (mouseX >= tp.x) && (mouseX <= tp.x+tp.width) ) { … } }</p> <a id="p99" href="#"></a> <h3>Drag And Drop</h3> <p><b>Change Cursor Depending On What Mouse Is Over</b></p> <p>theCanvas.setAttribute("style", "cursor: pointer”); theCanvas.setAttribute("style", "cursor:default" );</p> <a id="p100" href="#"></a> <h3>1945</h3> <p>• • • • • • • • Demo Use images are particles Scrolling on multiple Layers Multiple object pools Spritelib Ari Feldman http://www.widgetworx.com</p> <p>Music from musopen.org </p> <a id="p101" href="#"></a> <h3>1945</h3> <p>• • • • • • • • • • • • • •</p> <p><b>(ugly) hitTest() Bounding Box. Objects need x,y, width, height</b></p> <p>function hitTest(image1,image2) { r1left = image1.x; r1top = image1.y; r1right = image1.x + image1.width; r1bottom = image1.y + image1.height; r2left = image2.x; r2top = image2.y; r2right = image2.x + image2.width; r2bottom = image2.y + image2.height; retval = false; if ( (r1left > r2right) || (r1right < r2left) || (r1bottom < r2top) || (r1top > r2bottom) ) { retval = false; } else { retval = true; } return retval; }</p> <a id="p102" href="#"></a> <h3>Color Drop</h3> <p>• • • Demo Replaced a similar a Flash game Since these are not DOM Objects I found that I needed to Create my own EventListener class • to make this work Like Flash Works almost identically on Mobile (besides sound issues)</p> <a id="p103" href="#"></a> <h3>Match 3</h3> <p>• •</p> <h3>Demo</h3> <p>Color Drop iteration</p> <a id="p104" href="#"></a> <h3>Duck Game </h3> <p>• • • Cross Platform Web/Mobile Game Touch controls/mouse controls Replacement for Flash</p> <a id="p105" href="#"></a> <h3>Duck Game</h3> <p>• Created to replace a Flash game and work on all devices. • We add in particle effects and control that Would work across platforms.</p> <p>When doing touch (slide of finger rather than Click, we use two separate functions for mouse coordinate detection that in turn call the same function for movement: allMoveHandler() Demo</p> <a id="p106" href="#"></a> <h3>Duck Game</h3> <p>• } Example of mouse v. touch For Browsers: function onMouseMove(e) { mouseX=e.clientX-theCanvas.offsetLeft; mouseY=e.clientY-theCanvas.offsetTop; allMoveHandler(mouseX,mouseY);</p> <a id="p107" href="#"></a> <h3>Duck Game</h3> <p>• Example of mouse v. touch For Mobile: function onTouchMove(e) { targetEvent = e.touches.item(0); touchX=targetEvent.clientX-theCanvas.offsetLeft; touchY=targetEvent.clientY-theCanvas.offsetTop; allMoveHandler(touchX,touchY); e.preventDefault(); }</p> <a id="p108" href="#"></a> <h3>Flash Header Replacement</h3> <a id="p109" href="#"></a> <h3>Header Replacement</h3> <p>Client asked for a Flash header first, but we suggested HTML5 so it would work cross platform.</p> <h3>Flash Demo</h3> <a id="p110" href="#"></a> <h3>Header Replacement</h3> <p>To create the HTML5 version we needed to export all of the animations and layer the images in the same manner as the Flash layers to create a mask-like look to the animation.</p> <h3>HTML5 Version</h3> <a id="p111" href="#"></a> <h3>Header Replacement</h3> <p>The HTML5 Mouse Pointer was simulated by swapping out the css properties for the Canvas when we detected the mouse over an interactive element: theCanvas.setAttribute("style", "cursor:pointer");</p> <a id="p112" href="#"></a> <h3>Asteroids </h3> <p>An arcade game like Asteroids can be created by continually updating the Canvas and all logical objects: </p> <a id="p113" href="#"></a> <h3>Asteroids </h3> <p>An arcade game like Asteroids can be created using pure path drawing, or with bitmaps, or with a combination of both.</p> <h3>Path Example: Tile Sheet Bitmap Example With Skip Timer:</h3> <a id="p114" href="#"></a> <h3>Asteroids </h3> <p>The basic version uses a regular interval, while the extended, color, bitmap version uses particle pools, and a frame skip timer that attempts to keep the frame rate as fast as possible on various devices.</p> <a id="p115" href="#"></a> <h3>Asteroids (frame step counter) </h3> <p>//*** new FrameRateCounter object prototype function FrameRateCounter(fps) { if (fps == undefined){ this.fps=40 }else{ this.fps=fps } this.lastFrameCount=0; var dateTemp =new Date(); this.frameLast=dateTemp.getTime(); delete dateTemp; this.frameCtr=0; } this.lastTime=dateTemp.getTime(); this.step=1;</p> <a id="p116" href="#"></a> <h3>Asteroids (frame step counter) </h3> <p>FrameRateCounter.prototype.countFrames=function() { var dateTemp =new Date(); var timeDifference=dateTemp.getTime()-this.lastTime; this.step=(timeDifference/1000)*this.fps; this.lastTime=dateTemp.getTime(); this.frameCtr++; if (dateTemp.getTime() >=this.frameLast+1000) { this.lastFrameCount=this.frameCtr; this.frameCtr=0; this.frameLast=dateTemp.getTime(); } } delete dateTemp;</p> <a id="p117" href="#"></a> <h3>Asteroids (frame step counter) </h3> <p>The frame counter is called one each interval to update the step value: frameRateCounter.countFrames(); Individual objects use the step value to update positions: tempParticle.x+=tempParticle.dx*frameRateCounter.step;</p> <a id="p118" href="#"></a> <p>• • 3D Context</p> <h3>Demo 3D with webGL</h3> <a id="p119" href="#"></a> <h3>WebGL</h3> <p>• The API is managed by Kronos, the same organization that manages OpenGL. In fact, much of <i>WebGL </i>is similar to programming in OpenGL. </p> <a id="p120" href="#"></a> <h3>Some WebGL JS Libraries</h3> <p>• • • • • •</p> <p><b>Google O3D : </b></p> <p>http://code.google.com/p/o3d/</p> <p><b>GLGE : </b></p> <p>http://www.glge.org/</p> <p><b>C3DL : </b></p> <p>http://www.c3dl.org/ <b>SpiderGL : </b>http://spidergl.org/</p> <p><b>SceneJS : </b></p> <p>http://scenejs.org/</p> <p><b>Copperlicht : </b></p> <p>http://www.ambiera.com/copperlicht/</p> <a id="p121" href="#"></a> <h3>Learn More About WebGL</h3> <p>• The best place to learn about <i>WebGL </i>is the site </p> <h3>http://learningwebgl.com/</h3> <a id="p122" href="#"></a> <h3>Libraries And Tools</h3> <p>• • • • • • Box2D http://box2d-js.sourceforge.net/ Translated from the AS3 version Cocos 2D http://cocos2d-javascript.org/about Can handle phyics, sprites, tile maps, and more PhoneGap – Turn a canvas app (or and html4/5 compliant app) into a mobile app. http://phonegap.com/ AppMobi – Canvas acceleration using their online tools direct at game developers http://phonegap.com/ Impact.js – A game library for rapid game development http://impactjs.com/ More and more popping up every day</p> <a id="p123" href="#"></a> <h3>What’s Next?</h3> <p>• • • • • A Flash-like tool (Edge?) for animation More devices need GPU support Better HTML5 Audio (Zynga Jukebox? Uses Flash as Fallback) Camera/Microphone support What would you like to see next?</p> <a id="p124" href="#"></a> <h3>Contact Us</h3> <p>• • •</p> <h3>http://www.8bitrocket.com</h3> <h3>info@8bitrocket.com</h3> <p>Twitter@8bitrocket</p> </div> </section> </div> </div> </div> </main> <footer> <div class="container mt-3"> <div class="row justify-content-between"> <div class="col"> <a href="/"> <img src="/theme/studyslide/static/logo-slideum.png" /> </a> </div> </div> <div class="row mt-3"> <ul class="col-sm-6 list-unstyled"> <li> <h6 class="mb-3">Company</h6> <li> <i class="fa fa-location-arrow"></i> Nicosia Constantinou Palaiologou 16, Palouriotissa, 1040 <li> <i class="fa fa-phone"></i> +357 64-733-402 <li> <i class="fa fa-envelope"></i> info@slideum.com </ul> <ul class="col-6 col-sm-3 list-unstyled"> <li> <h6 class="mb-3">Links</h6> <li> <a href="/about">About</a> <li> <a href="/contacts">Contact</a> <li> <a href="/faq">Help / FAQ</a> </ul> <ul class="col-6 col-sm-3 list-unstyled"> <li> <h6 class="mb-3">Legal</h6> <li> <a href="/terms">Terms of Service</a> <li> <a href="/privacy">Privacy policy</a> <li> <a href="/page.html?code=public.usefull.cookie">Cookie policy</a> <li> <a href="/page.html?code=public.usefull.disclaimer">Disclaimer</a> </ul> </div> <hr> <p>slideum.com © 2026, Inc. 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