【正文】 math department ? 3D graphics became more popular in the 1990s in gaming, multimedia and animation. In 1996, Quake, one of the first fully 3D games, was released. In 1995, Toy Story, the first fulllength putergenerated animation film, was released in cinemas worldwide. Since then, puter graphics have bee more accurate and detailed, due to more advanced puters and better 3D modelling software applications, such as Cinema 4D. Hefei university of technology math department puter graphical system ? 1. working process ? 2. basic ponents Hefei university of technology math department ? 1. working process ? Computer graphical system including two parts: software and hardware – Computer execute the application program – Data Input: graphical input device, database, interactive device – Data is anized by data structure – Call the saved graphical display subprogram Hefei university of technology math department Hefei university of technology math department ? Hardware – Display processor – Refresh processor – Interactive device – Hard copy device – puter Hefei university of technology math department Hefei university of technology math department ? Software – Application program – Application data structure – Graphical system Hefei university of technology math department Hefei university of technology math department Introduction to Computer Graphics Lecture 2 General Graphics Systems Hefei university of technology math department ? Announcement – Class web site is up ? Overview – Read Chapter 2 – Display devices – Graphics hardware – Input devices – Graphics Software Hefei university of technology math department Display technologies ? Cathode Ray Tubes (CRTs) – Most mon display device today – Evacuated glass bottle – Extremely high voltage Hefei university of technology math department CRT details – Heating element (filament) – Electrons pulled towards anode focusing cylinder – Vertical and horizontal deflection plates – Beam strikes phosphor coating on front of tube Hefei university of technology math department Electron gun ? Contains a filament that, when heated, emits a stream of electrons ? Electrons are focused with an electromag into a sharp beam and directed to a specific point of the face of the picture tube ? The front surface of the picture tube is coated with small phospher dots ? When the beam hits a phospher dot it glows with a brightness proportional to the strength of the beam and how long it is hit Hefei university of technology math department CRT characteristics ? What‘s the largest (diagonal) CRT you‘ve seen? – Why is that the largest? ? Evacuated tube == massive glass ? Symmetrical electron paths (corners vs. center) ? How might one measure CRT capabilities? – Size of tube – Brightness of phosphers vs. darkness of tube – Speed of electron gun – Width of electron beam – Pixels? Hefei university of technology math department Display technologies: CRTs ? Vector Displays – Anybody remember Battlezone? Tempest? Hefei university of technology math department Display technologies: CRTs ? Vector Displays – Early puter displays: basically an oscilloscope – Control X,Y with vertical/horizontal plate voltage – Often used intensity as Z (close things were brighter) ? Name two disadvantages ? Just does wireframe ? Complex scenes cause visible flicker Hefei university of technology math department Display technologies: CRTs ? Raster Displays – Raster: A rectangular array of points or dots – Pixel: One dot or picture element of the raster – Scan line: A row of pixels Hefei university of technology math department Display technologies: CRTs ? Raster Displays – Black and white television: an oscilloscope with a fixed scan pattern: left to right, top to bottom ? As beam sweeps across entire face of CRT, beam intensity changes to reflect brightness – Analog signal vs. digital display Hefei university of technology math department Display technologies: CRT ? Can a puter display work like a black and white TV? – Must synchronize ? Your program makes decisions about the intensity signal at the pace of the CPU… ? The screen is ―painted‖ at the pace of the electron gun scanning the raster – Solution: special memory to buffer image with scanout synchronous to the raster. We call this the framebuffer. – Digital description to analog signal to digital display Hefei university of technology