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Acorn Arcade forums: News and features: Games FAQ
 

Games FAQ

Posted by Foggy on 01:00, 11/7/2001 | , ,
 

What are 3D games, and exactly how 3D are they?


 
3D seems to have been the buzz word for games this year. On all platforms, new 3D games are being released at a phenomenal rate, and old classics are being re-released with alleged 3D effects . Basically this all amounts to the same thing, depth of perception.


The first 3D games attempted to immerse you in a pseudo three dimensional environment. This was often employed by means of a maze type game, which has progressed over the years through to Doom and Quake style games. With the latest generation of these games, 3D objects are created as true models, so that you can move around an object and view it from all angles.


This is the main difference where original 2D games are concerned as they haven't really changed. They are still two dimensional and work along one plane of view, but objects on the screen are given a sense of depth.


 

How can 3D objects be viewed on a 2D screen?


 
It's all done with mirrors as far as I know.


Although you are viewing the game on a two dimensional screen, by using perspective, games such as Quake can purvey the illusion that you are actually looking at a three dimensional environment. This effect works in the same way as looking at a painting of a building. If drawn correctly you can visualise the true dimensions of the object, even though it's on a canvas.


Very basic 3D games will make distant objects larger as they get closer to the player. These could be walls, monsters, or space craft for example.


 

Are Polygons better than sprites?


 
Are Mars bars better than Curly Wurlys?


This usually comes down to the type of game that is being played. Games such as Lemmings and TechnoDream, use sprites as they do not need to convey a true 3D image. Using sprites, often means that the computer has less processing to do. This can mean that the game can work on older machines with very little problem, as fast CPU's are not needed.


Games in the Doom and Quake genre, tend to be Polygon based. This means that as objects get closer or further away, they can be scaled in size and look much more realistic. There are several drawbacks with both polygons and sprites. Polygons tend to offer a much more realistic gaming environment, but are very processor intensive (drawing the screen,
fps etc) and can look blurred close up. Sprites on the other hand, tend to be less processor intensive, but look very jagged and blocky close up. This problem can be seen when you get close to a monster in Doom.


As a compromise many new games now employ a mixture of both polygons and sprites. As sprites can look very convincing at a distance, they are often used as backgrounds, where as polygons are used for objects that appear closer to the player. Texture mapping is a method used in games such as Descent where objects are constructed from polygons, but have tiled sprites over layed on top of them to create a more convincing image, both close up and at a distance.


 

What is a graphics engine?


 
As with a car, the engine is the part that does all the hard work behind the scenes. The graphic engine's job, is to work out where everything is on screen, what relationship each object has to you and then to render it at as high a
frame rate as possible.


There are many types of graphics engine, most of which have specific names, such as the TAG Engine and the Quake Engine.


Graphics engines are constantly being improved to include new features to make gaming more realistic. Features now seen in new games can include real time lighting effects (for flames and torches) and transparency (water, mirrors). A great deal of time is put in to designing a graphics engine as it is often the pivotal part of a game. Owing to this, controversy can occur over which graphics engine is considered to be superior.


 

What is this fps business?



FPS (Frames Per Second). Commonly used in Vision Express stores as a means of measuring commission to sales assistants.


It actually refers to the amount of times the screen is updated. To help immerse the player in to a true gaming environment, a high frame rate can make all the difference.


You may have seen basic cartoons made out of a small notebook. Each page has the same picture on it, but with slight variations. When the pages are flicked through in front of you, they create the illusion of movement. This is basically how computer monitors and televisions work. They update the whole screen (often referred to as a frame) many times each second.


Once the frame rate reaches around 25 fps, the human eye can no longer see individual images, and is tricked in to thinking it is actually seeing a moving image. European and Australian television (PAL TV standard) is broadcast at 25 fps, where as American television (NTSC TV standard) runs at 30 fps. The new DVD films run at 30fps.


Frame rates seem to reach their best at 25 to 30 fps, but many games try to achieve higher rates than this, sometimes around the 100 fps mark. This is because the computer has to do a lot of work to figure out what is displayed on the screen for each frame. This is useful in games such as Quake where a lot of monsters can be on screen at once. Because the computer now needs to work out where all the extra characters are on screen, it takes longer to draw each frame, and the result is that you'll find the screen jumps, and doesn't look as smooth as it did during "quieter" parts of the game. Thus the actual frame rate may drop to an unacceptable figure, such as 10fps and the eye is no longer tricked in to thinking it is looking at smooth movement. Because the
graphics engine may be able to calculate 100 fps it has enough power to cope with demanding situations like this, even though the human eye does not really register a higher frame rate.


 

What is a good screenmode for games?


 
This all comes down to which monitor you are using and which computer you have got. Generally, the bigger the
screen mode the more realistic the game appears. However, there can be drawbacks with this. Because the screen resolution is larger, the computer needs more time to draw each frame, and you could find that the frame rate is unacceptably low.


Most games have information on which screenmode best suits your monitor and computer. I'll compile a list here when I actually find any Acorn games that work on my machines. Doh!


 

What is Game On/StrongCache and how do I use it/Why do I need it?


 
When the StrongARM was released, the internal architecture of the processor had changed slightly. Because of this change, some games failed to work properly, especially those with software protection employing self modifying code.
Martin Friar's Web site is a good place to look for information and compatability lists. Many games can however be made to run, if a little slower than normal, by altering the state of the StrongARM's cache.


These instructions can be issued by normal star commands at the Command Line or in a Task Window.


 

*cache on   Turns the cache on.

*cache off   Turns all of the cache off.

*cache iw   Turns off the data cache. Many games respond well to this.

*cache idw   Turns all the caches on.

*cache w   Turns off the instruction and data cache.

 


The problem with altering the state of your cache is that your machine will run extremely slowly until it is turned back on. Various programs have been written to organise the state of the cache for you (and also include other features) so that games will run on StrongARM machines. These are listed below, but I recommend you look at each programs website to see if it works with your software first.


 
Game On! (Commercial)
This program allows a large amount of games and other programs to work on StrongARM machines. A database of software titles that currently work in Game On! can be downloaded from the Game On! website.


Strong Cache (Public Domain)
This is a module that allows the cache to be turned on or off from the keyboard and can fix a number of games.


Strong Cache 2 (Commercial)
This program works in a similar way to the above, but has been given more features. E.g. the cache can now be turned off with a timer. Because of the extra functionality of Strong Cache 2, it fixes more programs.


Strong Guard (Commercial)
Again, this program allows more games to work correctly with StrongARM machines.


 

How can I play games on the Internet?


 
Firstly, you'll need shares in your phone company, or have Internet access at work. Playing games over the Internet is fun, but can be extremely expensive, so is usually best left until the Weekend. Currently, the only game I can think of with "working" Internet functions is Peter Teichmann's !ArcQuake. On a StrongARM RiscPC, you should be able to get 10fps at 320 X 256 resolution on a decent server. There are instructions for setting up !ArcQuake for Internet gaming on my
ArgoNet Acorn FAQ Website. You should be able to alter the instructions to work with your ISP. This page also contains links to lists of servers. If possible, try to use a server that is geographically close to you to avoid bad lag times.


 


What is lag?


 
Lag is the curse of the Internet, and even more so for Internet gaming. As you may have seen on the news, when the presenter is talking to a correspondent on the other side of the world, there is a pause between the question being asked and the correspondent replying. This is because there is a time delay (lag) as the signal is transmitted.


The same sort of thing also happens on the Internet, but for a variety of different reasons. The main problem when playing games is that even if you're reactions are fast enough, the computer you're connected to, may not be told what you did until a few seconds after you did it.


Playing Quake for example, if you saw another player about to fire on you with a rocket launcher, you would normally side step out of the way and congratulate yourself on being clever. If you have a high lag time however, the server running the game, may not receive the instruction that you side stepped, until too late, resulting in your untimely demise.


There is always going to be an element of lag over the internet, but it is essential for games that the lag time whilst playing is in milliseconds rather than seconds. If you are getting a lag time in seconds, it's time to look for a new server, or play at less busy times.


 

What mode definitions do I need for , and where can I get them?


 
The best places to look for Monitor Definition Files (MDF's) for use with RiscPC's are currently the
Acorn Cybervillage, and Foggy's MDF page. Both sites have MDF files for use with a variety of monitors. My site also contains a "Pick 'N' Mix" section where I've put an MDF file that should be suitable for most monitors. If you can't find a mode you need, it may well be listed there.
 
 
 


 

Comments and questions should be sent to foggy@acornarcade.com, whilst death threats should be sent to dave@acornarcade.com.

 
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Acorn Arcade forums: News and features: Games FAQ