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Glossary

Have you read about the fabled PAL 60/50hz debate but never known exaclty what it is? Ever read a review where we've said how good a game's alpha blending effects are but had no idea what we're talking about? Well, here we'll try to explain a lot of the technical terms that we use, and hopefully our ramblings will begin to make more sense. If, however, you're a techie yourself, and you think that one or more of our definitions is wrong, please feel free to put us in our place by e-mailing us at staff@silicon-fusion.com

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50Hz (TV modes)
PAL and SECAM televisions (used in Europe) update the screen at 50 times a second, but have more lines on the screen than 60Hz televisions (so they display a less-smooth but higher-resolution picture). Since most games are programmed for NTSC standards, when they are converted to the 50Hz mode the extra lines either force the programmers to increase the resolution of the image produced (which can sacrifice frame rates) or leave it at the lower resolution and force players to view the game with borders on the screen. Since most modern European TVs support a 60Hz mode, some new games have a PAL-60 mode which should run full-screen and full-speed.

60Hz (TV modes)
NTSC televisions, which are used mainly in America, update the screen 60 times a second, but have less lines on the screen than 50Hz televisions (so they display a smoother but lower-resolution picture).

a
Alpha (stage of game production)
A game is said to have gone into the alpha stage of production when it has begun internal testing by the team that are working on it. This usually means that the program has got past the design stage, but still has fundamental bugs that are being worked out. After Alpha testing, the game will go into Beta testing, where members of the public, or a specific testing department in the company, will iron out more minor problems before the game hits the shops.

Alpha (graphics)
Any colour can be made up by mixing Red, Green and Blue light (see RGB), but in modern graphics engines you can also specify an Alpha value, which determines how transparent a surface will appear. For instance, if you have a cube where you set the colour to be 50% Red, 0% Green, 50% Blue and 50% Alpha, it would be semi-transparent (so you could see objects through it) and purple in colour. See also RGBA.

Alpha Blending (graphics)
This refers to how the game displays transparent objects. Usually, if an object is semi-transparent, the graphics engine simply takes a proportion of the object's own colour and mixes it with a proportion of the background colour (or the colour of an object behind it) to give the 'see through' effect. However, in some cases, the colours can be added together, which produces a brighter mix of colours (used mostly in special effects, such as fire or laserbeams), or subtracted to produce a darker colour. Also, some graphics engines allow the images seen through a transparent object to be distorted, to give the illusion of refraction (see Refraction), such as when you look at a sea bed through water, it appears to move with the ripples on the water's surface (especially effective in titles such as Wave Race: Blue Storm)

AV (cables)
AV (audio-visual) cables usually have three sockets, one of which carries the picture and two for stereo sound. The picture contains a mix of all three colour channels, and so quality is not as good as S-Video or RGB. However, the sound quality is very good.

b
Blitting (graphics)
Blitting is where pictures or shapes are drawn on the screen pixel-by-pixel. Every image you see in a game is drawn in this way at some stage or another, but usually it is handled by low-level-code so programmers don't have to worry about specifying each pixel of the image to be drawn.

c
CISC (hardware)
Stands for Complex Intruction Set Computer and applies to the processor inside most PCs. Since PCs have to cope with backwards compatibility issues (so that a modern PC can run programs designed for a 10-year-old model), they have much more complicated instruction sets than most console processors (see RISC (hardware)) and so require a higher clock speed to produce the same outcome that a relatively slow RISC system can.

Clipping (graphics)
Modern graphics engines try not to display objects that you can't see in your view. For instance, if there are two cubes, where one is in front of you and one's behind you, the engine should draw the one in front because you can see it, but not the one behind, because it would simple waste valuable processing time. Clipping is the word that describes the non-drawing of objects or polygons that aren't seen, although sometimes you get visible clipping where objects pop-up as they come into view because the clipping area hasn't been properly specified, or has been made intentionally too small to increase the game's frame rate.

Colour Depth (graphics)
The more colours an image (texture) contains, the more memory it takes up. The Colour Depth of an image represents the number of bits of memory taken up by a single pixel of an image. If an image has an 8-bit colour depth, each pixel can be one of 256 different colours, whereas a 32-bit colour depth allows a pixel to be one of 4 billion different colours, but means that it takes up 4 times as much memory to store.

f
Frame-Rate/FPS (graphics)
The frame rate of a game represents how smoothly it runs. If you see a video running at 30 frames-per-second (fps), then 30 different frames are being drawn every second and the video looks to be fairly smooth. However, if you see the same video running at 5 fps, it will look incredibly jerky and sometimes quite difficult to watch, because the motion is being split into only 5 frames every second, and your eye finds it more difficult to track the objects as they move.

Fogging (graphics)
In the "good ol' days", graphics engines and hardware were a bit pants, and found it very difficult to draw scenes far into the distance because it required too much processing power. So, some bright spark decided to make his/her levels foggy to hide the fact that nothing beyond twenty metres was actually being drawn, and shortly after it seemed that every game was using it. The N64 in particular suffered considerably from the over-use of this effect, and fortunately in most modern games it has been reduced to no more than a slight mist, but never-the-less it is still present in some for this very reason. Of course, there are also games out there that use it for it's proper purpose - to add atmospheric fog to some scenes, so don't slag off a game too much if you see the odd bit of water vapour here and there.

p
PAL (TV modes)
The PAL (Phase Alternation Lines) standard displays images containing 625 horizontal lines at 50Hz (50 frames per second). It is used in hundreds of countries around the world including many in Europe, South America and the East.

PAL-60 (TV modes)
Most modern European TVs have a PAL-60 mode, where the television will support a 60Hz signal (see 60Hz (TV modes)). Although games using this mode will be at a lower-resolution than those running full-screen in 50Hz mode, the difference is hardly noticeable, and usually the frame rate is a lot higher.

Polygons (graphics)
Most graphics engines use polygons to draw objects, before then texturing the faces with images to make them look more detailed. The polygons themselves are usually just triangles or squares, where three or four 3D points (X,Y and Z) let the engine know where in a scene it is to be drawn.

Pop-up (graphics)
When drawing a scene, the fewer polygons that have to be calculated and displayed the more smoothly the scene will move. So, if you want your game to take place in a city, having close-up shots from in a single street is good because the engine will only have to draw the polygons in that part of the city and the rest can be temporarily forgotten. However, if you zoom out of the street, until you can see the surrounding streets, then the block, and finally the city as a whole, now the game is having to draw everything at once, and it will most likely slow down to a crawl. So, to prevent this from happening, game programmers decide on a clipping distance, whereby any object further than that distance from the view is simply not drawn (see Clipping (graphics)). However, in games where you're moving forwards constantly, such as racing titles, objects that were once beyond this distance will get closer until they're inside the clipping distance and suddenly appear, or 'pop-up'. This is particularly bad if you're travelling at speed, since a wall could suddenly pop-up in front of you with little warning, causing you to crash from little fault of your own. More recently, programmers have used Fogging (see Fogging (graphics)) to hide this undesired side-effect.

r
Resolution (graphics)
The resolution at which a game runs determines the number of pixels (colour dots) displayed on the screen. A high resolution will run more slowly than a low one, because the graphics engine has to calculate extra detail and draw the extra pixels, which takes time, but the final image will look better and often clearer. Modern PCs run games in anything from 640x480 mode (640 pixels wide, 480 pixels tall, so over 300,000 pixels have to be drawn each frame) up to 1600x1200 (nearly 2 million pixels per frame) and beyond. However, unlike PC monitors, most televisions have a maximum resolution of just over 640x480, so most consoles don't produce images of a higher resolution than this. The Xbox is one of the few consoles to support the new HDTV (High Definition TeleVision) format which displays images at greater resolutions.

RF (cables)
RF is the antenna format for standard analogue TV signals, and in the early days most consoles came with RF cables because it was the only format most TVs supported. Unfortunately, it works by mixing together sound and video into a single, encoded analogue wave, which provides pretty poor picture and sound quality. Modern consoles tend to prefer AV or RGB cables.

RGB (cables)
In an RGB cable, the different colours used to make up the TV image are sent through separate channels, providing a greater level of quality. This is usually done through a SCART cable

RGB (graphics)
This refers to how colours are specified in games. Every colour can be made up by mixing Red, Green and Blue primary colours in different quantities.

RGBA (graphics)
This refers to how transparent surfaces are specified in games. In addition to Red, Green and Blue proportions, an additional Alpha proportion is specified, which determines how transparent a surface is (see Alpha (graphics)).

RISC (hardware)
Stands for Reduced Intruction Set Computer and applies to the processor inside most consoles. Since these processors only have to cope with a small number of basic instructions, they can execute them much faster than a CISC processor (see CISC (hardware)), and so don't have to have such a high clock speed to produce the same result as a CISC system. This is why most consoles seem to have a much slower processor speed when compared to PCs, but still produce the same (if not better) quality of graphics.

s
S-Video (cables)
The S-Video standard uses two channels for video and one for audio. The two video channels allow a luminence signal to be sent separately to the red and blue signals, so less interference occurs and the final picture is better than a full composite video signal. This still isn't as good as the RGB cable (see RGB (cables)) since interference can still occur between the Red and Blue signals.

t
Texture Mapping (graphics)
To make surfaces in games look more realistic, game engines often draw an image onto them to give them more detail. For instance, a cube in a game could represent any number of different real-life objects, but draw the image of wooden planks on the side with a 'This way up' notice and it becomes a warehouse box. The process of drawing an image onto the surface of an object is called Texture Mapping, where the image itself is known as a Texture.

Tri-Linear Mip-map Interpolation (graphics)
This mouthful of a term basically means that different textures are used on an object depending on how far away from the view it is. Since there's no point having a hugely detailed texture if an object is miles away in the distance, the graphics engine will instead pick a lower-resolution one to speed up drawing times. However, as the object gets closer, the engine will merge the higher and lower resolution images, so that you don't see a sudden jump when it switches from one to the other.

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