|★ GAMES ★ MAKING OF "Indiana Jones and the Last Crusade" ★|
|Games - Makingof - Indiana Jones 3 - Tiertex|
Indiana Jones and the Last Crusade is the latest exciting adventure movie from Lucasfilm. Manchester-based TIERTEX , whose recent work indudes Thunder Blade, were given the task of adapting the film to a home computer game.
The game is divided into four mam sections , each of which relates to a major action sequence from the film. Indeed, the actual script of the film was used to ensure that the game remained faithful to the overall concept of 'Indy' . The four sections of the game are 'The Cross of Coronado' . 'The Ascent of Castle Brunwald . 'On board the Zeppelin', and 'The Holy Grail'
Because of the large amount of graphics and data required, the game has been split into four multi-load sections (128K owners ; have the benefit of all the levels loading into memory at the same time).
The game was written on an Atari 1040STF wit,h a 20Mb SH205 hard disk. An inhouse Z80 assembler was used in conjunction with the Tempus program editor , customised shell , and specialised parallel communications software (also written inhouse). All graphics ware designed using Degas Elite on the Atari ST and then converted into Spectrum format by the communications software.
The background graphics for each level are held in the form of a map' which L constructed from 16 by 16 pixel 'blocks'. The width and height of each map is entirely variable and another inhouse utility program on the Atari ST was used to generate the maps for all the different versions.
Possibly the biggest problem with programming the game has been the large amount of data required by both the sprites and background graphics In order to reduce the amount of memory used by sprites, several important techniques were used.
Firstly, me mask data' for each sprite ( i.e the data which allows a sprite to overlay the background graphics correctly) were compressed to a quarter of their original size. This obviously introduces a time overhead when expanding the data but it was essential in order to fit the required graphics into the flame.
Secondly both mask and sprite data was shared between different objects. for example both Indy and the Cowboy sprites used the same mask data. They also use the same graphics for their legs The game also features a fair amount of digitised graphics. These are in the form of 'Interim screens'which are shown before each of the multi-load sections, and consist of a relevant scene from the film itself.
The game features a fully multi directional scroll routine which is locked to multiples of four pixels horizontally but can move any number of pixels vertically. The scroll acts as if the viewport was panning' across the map and is based relative to Indy 8 position within the map.
The 128K version includes the main Indy theme music, which was transcribed from John Williams original film score, and various jingles/sound FX. Unfortunately , the 48K version could only contain simple sound FX due to memory limitations.
TRICKS AND PROBLEMS
In order to optimise the scroll and map printing (which governs the speed at which the game executes), a 4K buffer is used into which the map and sprites are printed. A high efficient routine to copy the buffer to the real screen is synchronised with the frame flyback pulse in order to ensure that the game is entirely flicker-free.
As mentioned before, the sprite routine has to deal with expansion of mask data along with the usual problems which include reversal of sprite images (reducing the graphics required by half).
The main problem was still, of course, simply cramming the game Into the Spectrum.
A further step that was taken to reduce memory requirements was to multiload actual object code. This caused no end of problems since routines in both the main code and the multi load code would have to access each other. This in itself necessitated the use of 'jumpblocks'which occupy standard locations in order to reeference routines and variables correctly.
The game has been developed across oil the major formats at the tame time and the Spectrum version is in fact extremely close to the Atari ST version. The same logic has been used concerning the wav in which Indy walks, uses, his whip, etc so that all versions feel'and play the same way.
TIERTEX was founded two years ago by Dr John Prince and Electronics Engineer Donald Campbell. The company has offices in South Manchester and employs eight programmers in-houne plus two graphic artists and a musician.
Mark Haigh-Hutchinson was the programmer in charge of the Spectrum , Amstrad and IBM PC versions of the game. His previous Spectrum work includes Alien Highway and Overlander .Mark Tait composed the music and sound FX for the 128K version of the game.
Sinclair User #89 (August 1989)