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Talk Dirty to Me Back when I was a slender youth, the absolute cutting edge of computer-generated graphical wizardry had only one name, and that name was Tron. Yes, it's time I came out of the closet and declared publicly that I loved Tron. It had its faults, but whatever you thought, it was a landmark film, and Syd Mead is the god of design at whose altar I sharpen my pencils. Anyway, the reason I mention Tron, is that the CGI sequences from that movie illustrate one of the oldest problems with realism in computer graphics (not that Tron was trying to be realistic of course), and it all comes down to a question of filth. If you'll indulge yet another foray into the world of film, contrast if you will the hardware in 2001: A Space Odyssey with that of Alien, Dune or The Matrix. Look at the ships from the original Star Trek series and compare them with those from Star Trek: The Next Generation. There are many differences, not least of which is the move away from plastic and glue to computer graphics, but one clearly identifiable change is the level of accumulated grime and dirt that now forms an integral part of ship design. This doesn't just apply to vehicles, any element of a film that is not meant to look unnaturally pristine is dirtied down. Simulating the effect of wear and tear on objects and environments helps to avoid the appearance of the painfully cheap straight-out-of-the-box look that the original Star Trek (sorry, Mr. Roddenberry) so beautifully exemplified with its exotic other-world locations. Anything created on a computer will naturally be influenced by the mathematical precision involved in its creation, and this close association to order and perfection is one of our greatest enemies in the battle for realism. So, the first thing to do is to try and avoid using exact geometric shapes unless your design specifically requires them. Our eye is more sensitive than we often realize, and as the real world almost never presents us with perfect spheres, cubes, and so on, their appearance on our screen will make things less believable, even if the player can't quite identify what the problem is. Repeated geometry has the same effect. Like the looped background that scrolls by behind the main character's car in a cheap cartoon, exact repetition closely linked in time or space widens the reality gap. Fundamentally, it is the same problem as noticeably repeating textures. Game players are primed to accept a certain level of repetition -- limited resources demand that geometry and textures be reused as much as possible -- but the trick is of course disguising this repetition whenever possible. That, however, is a different problem. We were about to talk dirt. Your ability to create geometry that looks organic -- or at least imperfect -- will no doubt be hampered by the number of triangles available to you, and thus clever and economic modeling is the best way forward. However, it is in texturing that we can really make a difference. Chances are that you've come across the various plug-ins for our favorite 3D packages that take fresh, wholesome textures and make them dirty. With names along the lines of Filthmatic 2000 and Auto Slime, these programs add simulated dirt, often taking a long time and with varying degrees of success, but their principles of operation are sound. Edges, joins, and recesses all are areas that naturally accumulate filth. Wood gets worn easily, paint chips, and metal scratches and rusts. Of course I'm not suggesting that all our worlds take on the look of a long-abandoned munitions factory. It is just as bad to overindulge in squalor and enforced deterioration as it is to leave everything perfect. The right balance is our goal, and this will depend on the specific needs of your game. If you are working on a first-person shooter that is set in the abandoned munitions factories of post-communist Russia, by all means attack your locations with corrosion, coat them with filth, and leave a trail of decay wherever you tread. If, on the other hand, you are making a third-person action-adventure set in the world's largest hair salon, sheets of rusted iron will probably not feature prominently. You would, however, still need the environment to look as if it had been used, and textures that encourage a lived-in feel make all the difference.
It is only in the last few years that lighting has become available to the artist as a genuine tool of beautification in a real-time 3D game environment. We can now call upon the wonders of vertex lighting, dynamic lighting, shadow and light mapping, as well as tricks such as lens flare, specular lighting, and projected shadows. As always, your choice will be determined by who you work for and what you're working on, but there are some things that are applicable in most circumstances. First and most importantly, let's establish that game lighting is distinct and different from lighting in the real world; lighting for film, TV, theater, and photography; and lighting for single rendered images or prerendered animations. You can argue against any of these if you wish, and I concede that there are some rules that overlap slightly, but lighting a game environment is, on the whole, a discipline in itself. Following are some of the basic considerations Color. Have you noticed how nighttime lighting on TV and most films is just blue lighting? It bothers me more than it probably should, but the convention for night lighting has been firmly established, and is so prevalent that most people probably don't even see it any more. Realism would mean that the lights were just switched off and the viewers' eyes adjust as best they can to lower levels of illumination. Not surprisingly however, Tom Cruise insists that you see his orthodontically enhanced smile with equal clarity, both day and night, and so lighting finds a way. What have Tom Cruise's teeth got to do with the lights in my game, you ask? Hopefully nothing (unless you're working on a Hollywood dentistry simulation), other than helping me point out that the color of your light is important. Daylight -- perhaps the hardest to simulate -- has a cold, faintly blue quality that turns warmer at sunrise or sunset. Artificial light is generally more yellow and torch light somewhat orange, but rather than go through a large list of colors, all I am saying is observe what's around you, and be aware of the effect color has on the feel of your environment. You have a certain amount of freedom towards experimentation. Late evening light can be purple, alien lights can be green and pink, whatever works best -- but make sure that it does work. Highly saturated color needs to be handled with care as many a soul has been lost on the clashing rocks of color overkill, lured towards them by the siren song of 32-bit color, only to find that they've created the feel of a 1970s disco that the Bee Gees would be proud of. As a rule of thumb, if you find yourself looking for the best place to hang a mirror ball, take a step back and think seriously about toning things down.
When used as a legitimate gameplay device, darkness can create atmosphere and tension quite successfully, but it is at its most effective when used in contrast to relatively well-illuminated areas. Half-Life gave us many fine examples of the "I don't want to go in there, it's dark" syndrome -- a technique that would not have been so successful if the whole game were in near darkness. In terms of a single location, a contrast in illumination can draw attention to important elements, as well as diverting the player away from, shall we say, those areas that are less polished. Strong, uncomplicated lighting will add drama to a scene, especially if you can get away with low levels of ambient light, forcing the eye to the brightly lit areas.
Visible Sourcing. This just refers to the placement of objects within a scene that the player can identify as the sources of any lighting. Once again, the eye is quick to tell the brain when something is not quite right, and obvious light, especially with accompanying shadows, needs a definite source to work properly. Patches of nonsourced light are fine when used subtly, as long as they don't stand out sharply in an area of low ambient light. The Final Word Making things look fantastic in a game is a tall order. Gameplay is king, and his demands must be adhered to. Technical limitations mixed with the constant shifting of the goalposts that typifies most projects' fluidity mean that artists have to think on their feet, and be ready to compromise the purity of their creative vision for those extra frames per second when needed. As technology rolls on, however, the future promises to deliver the kind of power we need to completely unshackle the creative beast that lurks in shadowy depths of every game artist. Until then, the worlds we create can still be beautiful -- we just need to make sure that it's the right kind of beauty.
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