【導讀】二維動畫設計研究與應用。畢業(yè)設計（論文）原創(chuàng)性聲明和使用授權說明。導下進行的研究工作及取得的成果。盡我所知，除文中特別加以標注和致。謝的地方外，不包含其他人或組織已經(jīng)發(fā)表或公布過的研究成果，也不包。含我為獲得及其它教育機構的學位或?qū)W歷而使用過的材料。本研究提供過幫助和做出過貢獻的個人或集體，均已在文中作了明確的說。明并表示了謝意。本人完全了解大學關于收集、保存、使用畢業(yè)設計（論文）的。規(guī)定，即：按照學校要求提交畢業(yè)設計（論文）的印刷本和電子版本；學。校有權保存畢業(yè)設計（論文）的印刷本和電子版，并提供目錄檢索與閱覽。服務；學?？梢圆捎糜坝?、縮印、數(shù)字化或其它復制手段保存論文；在不。以贏利為目的前提下，學?？梢怨颊撐牡牟糠只蛉績?nèi)容。畢業(yè)設計（論文）專用紙

　　

【正文】 e cramming effort. What this means, at least until large screens and fast Inter connections bee the norm, is you can39。t yet do much with video. You can stream QuickTime, but without a leased line connection it39。s terrible. Thankfully, you still have a range of choices when it es to graphics animation. So, let39。s take a look at the main techniques, and their drawbacks, for getting your site animated today. Back in 1994, the backroom boys in mercial Web development came up with an extremely basic form of animation by sending consecutive GIF images live to the browser. Advertisers had been using this method to change ad banners every 30 seconds or so without waiting for the user to refresh the page. By sending a sequence of frames on a constant basis, an elementary animation effect was possible. The drawback, of course, was that graphic data was constantly being downloaded over the line after the page itself had loaded. On a modem, this meant the browser was always flickering and the hard disk churning, and frames were usually interspersed with blanks as each subsequent frame loaded. Soon after, the animated GIF was born, effectively packing the GIF frame sequence into one file which downloaded once. The animated GIF has been a staple of ad banners and simple attentiongrabbing effects ever since. Even sites which promote and showcase Flash and Shockwave interfaces still use animated GIFs because designers know that it39。s the one animation technology supported in every Web browser that lets you see graphics at all. The limitations of animated GIFs are wellknown, but let39。s summarise them anyway. GIFs are 畢業(yè)設計（論文）專用紙 第 26 頁 bitmap images, so e at a fixed size regardless of browser window size. They can reach quite exciting sizes if they include more than 10 frames or so, because pression is based on the number of different colours in each image. They also tend to appear in a jerky fashion during the download, leaving the user staring at a seemingly inexplicable sequence running at one frame every five seconds the first time round. More recently, designers have been able to produce basic path motion for static images using DHTML. Instead of running an animation in one fixed place, DHTML techniques let you take a single image and move it around over the top of your page as an independent, floating object. The nice thing about this approach is that the animation, for what it is, starts almost immediately and the movement is perfectly smooth, not being framebased. The graphic can also have a transparent background just like any GIF. The big drawback is that it doesn39。t do anything else terribly interesting. As a result it can e across as just plain annoying or tacky. And it39。s not really animation. While the World Wide Web Consortium squandered most of the 1990s considering some proper animation technologies, Macromedia just went for it. The result was Flash, a system of playing back selfcontained movies containing vectorbased graphics and text within a Web page or independently running in a Web browser. The advantages of the Flash approach are considerable, and getting more pelling as time goes on. In the first instance, the vector nature of Flash movies allows you to include quite plex graphics and sequences in the confidence that they39。ll press down to almost unfeasibly small file sizes. In practically every test, from simple rollover type and button effects to plete sequences, you39。ll find that Flash files are smaller than animated GIFs and load up faster than Java actions. Vectors also mean that the movies can resize themselves automatically to fit the browser screen, antialiasing on the fly. Better still, Flash movies can incorporate events and react to user input, making it terrific for developing custom Web page interfaces which HTML couldn39。t hope to imitate. Not least, Flash can include embedded audio. And perhaps best of all from an experienced designer39。s point of view, the movies can be set to start running as soon as the download mences without waiting for it to plete. There are 畢業(yè)設計（論文）專用紙 第 27 頁 two principal drawbacks to the Flash format. First, it requires your audience to have a plugin Flash player installed. However, to Macromedia39。s credit, the Flash plugin is a relatively small and speedy download at just a couple of hundred kilobytes. You should also be aware that Microsoft 3 intends dumping most of the plugins it currently ships with Inter Explorer in future but Flash is the very notable exception. The second drawback might not concern you, but it39。s that Flash isn39。t actually a standard in the same way as HTML, GIF, JPG, PNG or something like Java. Flash is a 100 per cent proprietary format owned by Macromedia and licensed out to other graphics software developers on a mercial basis. In practice, of course, it doesn39。t matter that Flash isn39。t an officially recognised standard because well over 90 per cent of Inter users already have the plugin installed: we39。re talking about hundreds of millions of people, ready to go with your animation content. Fun and sexy though Flash is, it39。s not a plete multimedia environment. Originally, Flash arose from a project at Macromedia to make Shockwave animations, already developed for Web playback, even more pact and accessible by people with slow modems. Shockwave is still very much alive and well, and in many cases leaves Flash way behind in terms of visual quality, interactivity and multifunctionality. There39。s even a lively market for cartoons and games using Shockwave and its offline player ShockMachine. Unlike Flash, however, the Shockwave plugin is a long download and requires a somewhat fiddly installation process which includes exiting your Web browser at one point. The big limitation of both Flash and