The technique of 3D has been growing in popularity. John Gilbert finds it is not always used in the best ways
THREE-DIMENSIONAL games are increasing in popularity and software houses are beginning to see that 3D techniques have great potential in a market where Space Invaders and Pac-man are rapidly becoming outdated.
Programmers are starting to use sophisticated techniques to achieve three-dimensional effects on the computer screen which seem more life-like than the two-dimensional space-battle games.
The effects are difficult to create, as the programmer is working in three planes, or directions, instead of the usual two. Most shapes are produced on the screen using X and Y co-ordinates which correspond to the flat horizontal and vertical dimensions. Three-dimensional shapes are constructed using an extra axis which, in theory, moves away from or towards the computer screen.
The new axis is called Z and it is the inclusion of that dimension which gives the three-dimensional figure its depth. When a 3D shape moves up, down and sideways it uses the X and Y dimensions. When it seems to move towards you on the screen it is using the Z axis, which exists only in theory, as the computer screen is flat and two-dimensional in shape.
J K Greye was the first company to produce games using three-dimensional effects on the ZX-81. The game was called 3D Monster Maze and the player had to move around a three-dimensional maze to find the exit and also to evade the deadly jaws of the dinosaur which prowled around the corridors.
Even those critics who dismissed the ZX-81 as a child's toy, had to admit that the program was innovative and well-presented. Monster Maze marked the rise of the use of 3D techniques on microcomputers as small as the ZX-81 and Spectrum.
After the release of 3D Monster Maze, everyone could see the potential of three-dimensional games and utility packages on small machines. Using 3D techniques programmers can portray events which seem real to computer users when they are playing a game.
Three-dimensional effects also hide the inadequacies of the computers on which games are played. The dinosaur which chased the player around a maze in the New Generation game was created using the standard ZX-81 character set. That is not noticeable when the game is being played and you could be forgiven for thinking that it used high-resolution graphics.
The use of 3D gives a game added depth but at the same time it can also be used to disguise a poor plot.
The latest game from New Generation Software, 3D Knot, is an example of that. While the game has a basic plot it is not deep enough when you strip away the 3D effects. That does not make it a complete failure in this case but it points to the fact that three-dimensional graphics are a means and not an end.
There are two types of three-dimensional effect. The first, and simplest to produce, is shown in the Artic Computing game for the 48K Spectrum, Combat Zone. The three-dimensional shapes are shown as line drawings with no shading. That means you can see all the lines of the shapes, including those which would normally be invisible if colouring and shading had been added to the figures.
Combat Zone, like so many other pieces of software for the Spectrum, is not new in concept. It is a version of the arcade game of the same name. Although the graphics are reasonable the animation of the line-drawn shapes is very jerky.
The plot involves the player as the last of a race of tank commanders. Enemy tanks and diamond-shaped spaceships are dotted round the landscape and it is the commander's job to destroy them.
The game involves plenty of action and credit must go to the programmers who have managed to produce images which do not bend out of perspective as they move. Artic seems to have taken the easy way out, however, as the program is so slow that it must use those notorious Sinclair line-drawing routines which are in the Spectrum ROM operating system.
The Sinclair graphics routines are not known for their speed, so it would have been better for Artic to write new graphics routines into the main body of the Combat Zone program.
The second type of three-dimensional image is produced reasonably well in the Quicksilva 48K Spectrum game, Time Gate. The graphics for that type of image are more difficult to produce, as the programmer has to shade and colour the shapes to produce a picture which looks three-dimensional.
If the shading or the shape of the image is even slightly incorrect the picture will appear to be distorted and the effect will ruin the playability of the game.
The three-dimensional effects created in Time Gate show a slight distortion of image, which can be noted when an enemy ship approaches closer to the viewing screen of the player's ship. The enemy seems to unfold its wings as it gets closer and in some cases it appears as if the fixed wings materialise from nowhere.
No doubt Quicksilva would explain that as a feature of the game but all too often features such as that are errors and are explained away too easily.
The ending of Time Gate is disappointing, as the three-dimensional technique seems to have been thrown out of the window. When you have destroyed the enemy you must approach its base planet. The planet becomes larger as if an approach is being made but the technique being used is so obvious that it is embarrassing to watch.
The program uses what again appears to be the Sinclair high-resolution routines to draw circles which start small and continue to grow bigger. As they increase in size the drawing process slows and the technique becomes even more obvious.
It would have been better to do what New Generation did with 3D Tunnel on the Spectrum and create several separate pictures in memory to switch on to the screen one at a time in sequence. That will produce an animated effect.
If Quicksilva used that technique the planet could have been produced in high resolution at several stages of approach and would have looked like a real planet and not a rope mat.
Time Gate has its technical faults where graphics are concerned but it is playable. The 3D Tunnel from New Generation, on the other hand, has what can only be described as brilliant and imaginative graphics but it is almost impossible to play to the end.
The game takes you and your laser base through an underground tunnel inhabited by rats, spiders, toads and a very impressive tube train. Unfortunately so much memory seems to have been used to create the three-dimensional effects that the movement of the player's laser base is awkward.
More attention could have been paid to that area of the game, as movement of the base is not smooth or quick enough. That is understandable, however, as a great deal of memory has been used to produce the displays. Apart from that problem 3D Tunnel has the best graphics for a Spectrum game.
There are still very few 3D games for Sinclair machines, although those available give confidence that this sphere is developing in the proper way.
In the next few months we could see a move away from 3D arcade games and into 3D adventure games. There are already a few graphics adventures on the market but they do not use 3D.
As 3D techniques are developed, computers will be better able to produce simulations of the real world. Adventures will become more exciting and arcade games more dynamic. The 3D field is, however, just starting to develop but it has a long way to go before perfect holographic images can be produced on a small computer.