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BOFFINS' CORNERI USED to be able to say you cannot put a virus on your computer by simply opening an e-mail message. Sad to say, this is no longer true. Somebody in Finland found a weakness in Eudora, Outlook and Netscape mail that allows a malicious attachment to load a virus into your system, even if you haven't opened the attachment. Initially it was thought that Eudora was not affected by this new method of attack, but it was later discovered that it was also susceptible. For a detailed explanation of the problem, plus links to download patches, surf to http://www.ciac.org/ciac/bulletins/i-077a.shtml.
As in cinematography, for movement to be smooth, each "frame" (picture) must differ only slightly from the previous frame, and be presented on your screen quickly after the last. Conventional wisdom says anything above 15 frames a second will be seen as smooth. To get the true 3-D look, a long and complicated process takes place for each frame. This process can be broken down into two major parts: getting the geometry correct and rendering each polygon. During the geometry portion, polygons are drawn and manipulated, forming a wire frame (an empty outline) model of the final frame. During this process the shape of the polygons - and how light inside the scene will be used - is determined. Finally, it is decided from what perspective the scene will be viewed. The computer's CPU normally does the geometry processing. The 3-D board executes the second aspect of 3-D processing, rendering. After the board receives the wire-frame model, the first step is to shade it. This process smoothes out edges created from attempting to make curved surfaces from blocky polygons. Two types of shading are used by game boards: "flat" and "Gouraud". The latter is by far the better. After shading, the model needs texture to look realistic. There are many techniques to handle problems that occur when attempting to add texture to a 2-D screen to make it look 3-D. For example, the edges where two textures come together often won't look smooth. One way of solving this is called "bilinear filtering", where instead of slapping the textures onto the image "as is", an average of the pixels around the two convergent textures is taken before applying the final bitmap. Another problem occurs when a long line is extended into the distance. Often the line won't appear straight. A technique known as "perspective correction" straightens this out. When reading raw benchmark scores - such as "this chip does 400 000 triangles a second" - it is imperative for comparison to know all the settings used during that test. You must know how many pixels are in those particular triangles, how they were shaded and what texturing techniques were used. Here are some other terms you should become familiar with: Alpha blending: A technique used to describe levels of transparency. For example, glass can be completely transparent, while stained glass is translucent. Anti-aliasing: The process of smoothing out lines and edges, making them straight. API: This stands for "Application Programmer's Interface". A developer can use an API to develop a standard application more easily. Bilinear filtering: A sophisticated texture mapping technique that, instead of plopping down the same texel (a texture element) in a given texture map, will take the average of several texels around the original map, eliminating the blockiness that can occur when an image changes perspective. Direct3D: A Microsoft low and high-level API that allows game developers to build games in a similar fashion. Frame rate: The number of frames a second that are being rendered. Gouraud shading: A shading technique in which different colours are used along a polygonal object's edges, making the sharp points appear round and smooth. MIP mapping: The process of having and using texture maps of several different resolutions in a single scene. Pixel: A dot on the screen of a certain colour. Thousands of dots together make an image. Point sampling: A simple texturing method which simply places the corresponding texels onto the image. Top of page
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