CS040 Student Forum IV

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Student Forum is a successive seminar class series at the first two years for ACM Class students.

In this class, each student ought to present a 30-minute lecture. The student ought to choose one of his interested topic, design the slides and present to the entire class. The evaluation is based on peer-review mechanism.

学子讲坛ACM班最独具特色的一门人文课程。每堂课由一名学生选择自己最感兴趣的话题进行演讲,自己设计内容,自己导演整个过程,向大家阐述其理解与认识。话题遍布天文地理,科学艺术。山川历史,古今人物,无所不及;阐理释道, 诗画人生,无所不容;稗官野史,奇门异术,亦可共欣赏之。 这是我们自己的讲坛,我们互相聆听、感悟,也彼此打开了精彩的内心世界。

The last presentation I gave is about Graphics. I made a rotating cube opening with 10 to 1 counting down with OpenGL…

design the dream world

Good afternoon, Professor Yu, ladies and gentlemen:

First of all, you may be curious about what it is on the screen.

Yeah, this is count down for my speech this year. Let’s go together! One o one o, one o o one, one o o o, one one one, one one o, one o one, one o o, one one, one o, one, zero!

On November 5th, 2009, East Mid 4-205, my first speech —— 《The magic power of mind——Beyond Imagination》led us to the world of linking memory and mind map. And I do wish this can help you a lot in your study. Nevertheless, just as the procedure to challenge miracles, practice makes perfect.

On June 3rd, 2010, East Down 104, my second lecture——《Do you believe in change?——Change we can believe in》led us come to the frustrated but outstanding life of Barak Obama. The key point we should remember is that, whatever circumstances we are in, we should always strive to make the change.

On the last semester, November 9th , East Down 205,only one week after I had just taken the bandage on my left arm, I give a speech which called —— 《品读书法,感悟中华》. I would be greatly appreciated if you can still remember the philosophy of the phrase“通会之际,人书俱老”.

And today, on June 7th, 2011, East Down 102, the final door of my speech is about to open——

My subject today is《Design the dream world —— Demos, Computer graphics and Human-computer interaction

Let’s have a look at the outline.

Usually, when talking about a subject, especially referring to science, we would first look at the history of it. However, I would like to talk about the motivation —— why I am interested in this field — I would introduce the history of demos, demo groups and demo parties, then I would show you the brief history of computer graphics and introduce sub-fields and applications to you. Finally, I would like to say something on human-computer interaction – about future dreams.

Why I am interested in graphics?

That should date back to the year 2000 or earlier, when I was still a primary school student. One day, I saw such a demo and it was totally, in one word, amazing.

Firstly, we can see a delicate material – oh, that’s the ceiling – and then the perspective is changing – yeah, it’s an animation – what? I am walking in a castle? – the caption said – The product will make you happy – but actually – if anyone out there who is the first time to see the animation must be – amazed , then you walk out of the castle – and see the world in the author’s heart.

Considering the time is limited, I’d better close the demo now.

When I was a young boy, I was greatly attracted by the amazing effect on the screen. It’s just like a real world.

After I reviewed the demo file, I was shocked again: it’s only 64 kbytes, while the opening animation I have written at the very beginning, the source file is 24 kbytes while the application is 762 kbytes.

How did they do that?

So I start to hunt for the answer. When I was a primary school student, I had no idea because I can only use the application called “画图” to draw pictures on the computer. When I was a junior high school student, I had got no idea because all the software such as Flash, 3DS Max, Photoshop cannot help me compute the demo in real-time in such a size. When I was in senior high school, I had no idea because I was busy with my competition in Informatics. Finally, I am a university student. I gradually realize that the more I know, the more I don’t know.

Anyway, before a deeper analysis is made, I would give a brief introduction of the word “demo”.

The word “demo” here has a specific meaning. A demo is a non-interactive multimedia presentation made within the computer subculture. It is also known as the demoscene. The key difference between a classical animation and a demo is that the display of a demo is computed in real time, making computing power considerations the biggest challenge. Demos are mostly composed of 3D animations mixed with all kinds of effects.

Then the question arises: When did demo begin? Does it have a long history?

Actually, the birth of demos can date back to 1980s. At that time, a lot of personal computer games were released for early equipment like the Commodore 64, ZX Spectrum, Atari ST and Commodore Amiga, including Copy protection to prevent unauthorized copies.

Some cracker groups started to release those games with the protection removed.

Initially, small demos were shown before the actual game, including music, animations and marquees with greetings which should represent the releasing group. The quality of these demos was quickly considered as a figurehead of the group. Intros, which belong to the group of demos, increased in quality, often touching the limits of the computer’s abilities. The cracker groups started a severe competition for being the first in releasing cracked copies of games.

At that moment, levering out copy protection decreased in importance for some artists inside the scene. They felt that programming ambitious demos was more challenging. While publishers improved their copy protections, the quality of demos increased as well. Often, the fame of well-known groups was based on their spectacular demos.

The introduction of 16-bit and 32-bit computer systems resulted in a new distribution of work inside the cracking groups, since the hardware allowed new possibilities. The creation of demos was divided in programming, music and graphics.

At the end of the 1980s, pirate copies increasingly became an issue for the software industry. The development of games for certain platforms was stopped entirely due to insufficient profit, some claimed that the cracker scene being responsible for the doom of the platform. Some games were released by crackers before they were released commercially. Authorities started to apply pressure on individuals and whole groups listed in the demo scene.

This led to the release of stand-alone demos computer art without the illegal distribution of computer games. With the increasing use of the Internet, the separation was complete. Cracked copies of computer games were available online for the masses with the crack attached. Often, greetings were only attached in a text file, while the demoscene separately distributed their work.

Who wrote these demos?

The demo at first I displayed is written by a demo group – farbrausch.

Demogroups frequently consist of students, young computer enthusiasts who spend days coding their demos. They are also called Demosceners. Demosceners rarely use their real names in demoscene contexts.

A demogroups is usually made up of three kind of people.


The coder is the demogroup’s programmer who creates the demo’s software framework and is responsible for the actual realtime state of the demo. While some coders specialize in developing system-level functionality, others codes specialize in making effects which are usually visual representations of mathematical formulas, such as fractals or metaballs.

In the 1990s, coders were most often entirely responsible for the demo’s flow and arrangement, including the effect’s synchronization to the music and sometimes even the design. Nowadays, software tools known as demotools are widely used, allowing this work to be done by a designer who does not have to be a coder. Many groups, however, still prefer that the coder takes most of the responsibility in the demomaking process, including the design.

In many cases, an attempt for excelling in several areas has resulted in one area outshadowing the others: for instance, coders who try to make music often come up with “coder music” which may be technically passable but lacks artistic ambitions. “Coder graphics” and “coder palettes” are similar terms for graphics and color schemes.

Graphic artist

Graphic artists create the visual coherency behind a demo, which include still pictures, design elements, fonts, colors, 3D objects, textures and animation.

Originally, there was a single type of graphician creating typical 2D graphics. Ever since demos started using complex 3D graphics, the main task of graphic artists is to build models of 3D objects.


Musicians are responsible for the composing, arranging, mixing and mastering the soundtracks and sound effects in the demo.

In the older days, musicians worked with trackers, and the world of tracked music was heavily dominated by demoscene musicians. In later times, it became possible for the PC demos to use streaming, high-quality music formats, and the musicians started to gradually change their tools to professional music sequencers. However, tracked music and other specialized formats still continue to be used in size-restricted intros as well as demos written for more restrictive platforms such as mobile devices and vintage computers.

How is demo developing nowadays?

When mentioning this aspect, let’s have a look at demo parties. A certain demo party is usually held once or twice a year. The demo party is usually held as a competition. Demogroups will present their demos. And the best works will be awarded. At first, only demo groups can attend the annual party and show off their new works. As more and more demo parties are founded, everyone can attend the party and enjoy the art of demo.

So, I believe that everyone should know something about demo. Let’s have a short break then. But do you remember the initial question? How can we have real-time computing displayed on the screen?

That should due to the development of computer graphics.

In 1950, the first graphics monitor is born as an assessor of a computer Whirlwind I in MIT.

1950年,第一台图形显示器作为美国麻省理工学院(MIT)旋风I号(Whirlwind I)计算机的附件诞生了。该显示器用一个类似于示波器的阴极射线管(CRT)来显示一些简单的图形。1958年美国Calcomp公司由联机的数字记录仪发展成滚筒式绘图仪,GerBer公司把数控机床发展成为平板式绘图仪。在整个50年代,只有电子管计算机,用机器语言编程,主要应用于科学计算,为这些计算机配置的图形设备仅具有输出功能。计算机图形学处于准备和酝酿时期,并称之为:“被动式”图形学。到50年代末期,MIT的林肯实验室在“旋风”计算机上开发SAGE空中防御体系,第一次使用了具有指挥和控制功能的CRT显示器,操作者可以用笔在屏幕上指出被确定的目标。与此同时,类似的技术在设计和生产过程中也陆续得到了应用,它预示着交互式计算机图形学的诞生。

Further advances in computing led to greater advancements in interactive computer graphics. In 1959, the TX-2 computer was developed at MIT. A light pen could be used to draw sketches on the computer using a softwareSketchpad. Using a light pen, Sketchpad allowed one to draw simple shapes on the computer screen, save them and even recall them later. The light pen itself had a small photoelectric cell in its tip. This cell emitted an electronic pulse whenever it was placed in front of a computer screen and the screen’s electron gun fired directly at it. By simply timing the electronic pulse with the current location of the electron gun, it was easy to pinpoint exactly where the pen was on the screen at any given moment. Once that was determined, the computer could then draw a cursor at that location.

1962年,MIT林肯实验室的Ivan E.Sutherland 发表了一篇题为“Sketchpad:一个人机交互通信的图形系统”的博士论文,他在论文中首次使用了计算机图形学“Computer Graphics”这个术语,证明了交互计算机图形学是一个可行的、有用的研究领域,从而确定了计算机图形学作为一个崭新的科学分支的独立地位。他在论文中所提出的一些基本概念和技术,如交互技术、分层存储符号的数据结构等至今还在广为应用。1964年MIT的教授Steven A. Coons提出了被后人称为超限插值的新思想,通过插值四条任意的边界曲线来构造曲面。同在60年代早期,法国雷诺汽车公司的工程师Pierre Bézier发展了一套被后人称为Bézier曲线、曲面的理论,成功地用于几何外形设计,并开发了用于汽车外形设计的UNISURF系统。Coons方法和Bézier方法是CAGD最早的开创性工作。值得一提的是,计算机图形学的最高奖是以 Coons的名字命名的,而获得第一届(1983)和第二届(1985) Steven A.Coons 奖的,恰好是Ivan E.Sutherland和Pierre Bézier,这也算是计算机图形学的一段佳话。

Any of the most important early breakthroughs in computer graphics research occurred at the University of Utah in the 1970s.

A student by the name of Edwin Catmull started at the University of Utah in 1970 and signed up for Sutherland’s computer graphics class. Catmull had been working on his degree in physics. Catmull loved animation yet quickly discovered that he didn’t have the talent for drawing. However, Catmull saw computers as the natural progression of animation and they wanted to be part of the revolution. The first animation that Catmull saw was his own. He created an animation of his hand opening and closing. It became one of his goals to produce a motion picture using computer graphics. In the same class, Fred Parke created an animation of his wife’s face. Therefore, UU was gaining quite a reputation.

As the UU computer graphics laboratory was attracting people from all over, John Warnock was one of those early pioneers; he would later found Adobe Systems and create a revolution in the publishing world with his PostScript page description language. Tom Stockham led the image processing group at UU which worked closely with the computer graphics lab. Jim Clark was also there; he would later found Silicon Graphics, Inc.

The first major advance in 3D computer graphics was created at UU by these early pioneers, the hidden-surface algorithm. In order to draw a representation of a 3D object on the screen, the computer must determine which surfaces are “behind” the object from the viewer’s perspective, and thus should be “hidden” when the computer creates the image.

70年代是计算机图形学发展过程中一个重要的历史时期。由于光栅显示器的产生,在60年代就已萌芽的光栅图形学算法,迅速发展起来,区域填充、裁剪、消隐等基本图形概念、及其相应算法纷纷诞生,图形学进入了第一个兴盛的时期,并开始出现实用的CAD图形系统。又因为通用、与设备无关的图形软件的发展,图形软件功能的标准化问题被提了出来。1974年,美国国家标准化局(ANSI)在ACM SIGGRAPH的一个与“与机器无关的图形技术”的工作会议上,提出了制定有关标准的基本规则。此后ACM专门成立了一个图形标准化委员会,开始制定有关标准。该委员会于1977、1979年先后制定和修改了“核心图形系统”(Core Graphics System)。ISO随后又发布了计算机图形接口CGI(Computer Graphics Interface)、计算机图形元文件标准CGM(Computer Graphics Metafile)、计算机图形核心系统GKS(Graphics Kernel system)、面向程序员的层次交互图形标准 PHIGS(Programmer’s Hierarchical Interactive Graphics Standard)等。这些标准的制定,为计算机图形学的推广、应用、资源信息共享,起到了重要作用。


In the 1980s, artists and graphic designers began to see the personal computer, particularly the Commodore Amiga and Macintosh, as a serious design tool, one that could save time and draw more accurately than other methods. In the late 1980s, SGI computers were used to create some of the first fully computer-generated short films at Pixar. The Macintosh remains a highly popular tool for computer graphics among graphic design studios and businesses. Modern computers, dating from the 1980s often use graphical user interfaces (GUI) to present data and information with symbols, icons and pictures, rather than text. Graphics are one of the five key elements of multimedia technology.


3D graphics became more popular in the 1990s in gaming, multimedia and animation. In 1995, Toy Story, the first full-length computer-generated animation film, was released in cinemas worldwide. In 1996, Quake, one of the first fully 3D games, was released. Since then, computer graphics have only become more detailed and realistic, due to more powerful graphics hardware and 3D modeling software.

最后,我们以SIGGRAPH会议的情况,来结束计算机图形学的历史回顾。ACM SIGGRAPH会议是计算机图形学最权威的国际会议,每年在美国召开,参加会议的人在50,000人左右。世界上没有第二个领域每年召开如此规模巨大的专业会议,SIGGRAPH会议很大程度上促进了图形学的发展。SIGGRAPH会议是由Brown大学教授Andries van Dam (Andy) 和IBM公司Sam Matsa在60年代中期发起的,全称是“the Special Interest Group on Computer Graphics and Interactive Techniques”。1974年,在Colorado大学召开了第一届SIGGRAPH 年会,并取得了巨大的成功,当时大约有600位来自世界各地的专家参加了会议。到了1997年,参加会议的人数已经增加到48,700。因为每年只录取大约50篇论文,在Computer Graphics杂志上发表,因此论文的学术水平较高,基本上代表了图形学的主流方向。

In summary, this presentation introduced demos and computer graphics as well as a little computer-human interaction.

I hope this presentation may give you a motivation to design your own dream world. No matter it is graphical or not. No matter it is on password, data management, system, basics, network, or artificial intelligence. With the map of mind, with the determination in our heart, we can make the change if we keep going!

Finally, I wish all of us could design our future, our dream world by our own hand!


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