REAL TIME SOLIDS MODELLER

Silicon Vision has now released its rewritten Real Time Solids Modeller for the Archimedes. Mike Williams investigates.

Silicon Vision is a company which has already established itself in the CAD field with its software for the BBC micro. Now the company has released a completely new version of its Real Time Solids Modeller for the Archimedes.

The large and impressive packaging contains just a single disc and a 45 page manual. In fact, the software consists of two separate components, the SolidCAD Design System for creating and editing 3D objects, and the Real-Time Graphics Language for animating 3D objects. These can be purchased separately if required. We will deal first with the design system.

As with other 3D CAD systems (Euclid from Ace Computing for example - see review in RISC User Volume 1 Issue 8), the SolidCAD Design System shows four separate views on the default screen: plan, front view, side view and 3D projection. There is also a menu to the right of the graphics area, and a two line display of information at the foot of the screen.

The main menu list consists of Edit, Panel, Style, Tools, Load and Macro. When any main menu option is selected a subsidiary menu also appears at the right of the screen, often including relevant parameters which can be changed with the mouse.

The software is very largely mouse controlled, but SolidCAD also responds to a number of single key commands, and so-called command line options for controlling the drawing environment. Although it might be felt that a wholly mouse controlled environment would be better, it works well in practice, and has the advantage that the commands can be used to create descriptions of drawings using a word processor, and these descriptions may then be EXECed into the package.

As with any 3D system it takes quite some time to become familiar with the four screen views, and their relationships to each other. The X-Y plane is used for the front elevation, with the Z axis providing depth (and both 1st and 3rd angle projections are supported). All drawing takes place in one of the three 2D views, and is immediately reflected in the display of the other views. All four views can be zoomed in and out, and the image translated up, down, left or right. The 3D projection can also be rotated about any of the three axes. The current state of all these parameters can be displayed by selecting the Panel option from the main menu.

CREATING 3D OBJECTS

Objects are built up from facets (faces) that can be drawn in any plane view using a rubber-banding technique. Closed objects can be automatically completed by pressing 'F'. In addition, any face can be drawn to form the basis of a solid by extrusion or by rotation. Extrusion forms a solid using the face as a cross-section. The user determines the direction and extent of the extrusion. Perhaps the simplest example is the extrusion of a square to form a cube.

Solid objects can also be created by rotating a plane face about an axis. The user can control both the step size to be used and whether a full or partial rotation is required. With a suitable cross-section, a torus (or doughnut shape) can be readily formed for example.

COLOURING AND SHADING

The Style menu controls the way in which objects are displayed on the screen. The default is for a complete wire frame object, which has the merit of being fast. The Surface option shows a similar wire frame view, but with hidden line removal . A number of additional options (catering for both convex and concave shapes) allow all the faces of 3D objects to be coloured, giving a really solid appearance.

SolidCAD can be used in mode 12 (16 colours) or mode 15 (256 colours), and of course with multi-sync modes 20 and 21, and the current drawing colour selected from a colour menu. There is also a smooth shading option, which introduces shades of the selected colour, but I found considerable trial and error seemed to be necessary, adjusting the various lighting parameters, to obtain a pleasing result. Smooth shading transforms a facetted object into one with much smoother contours. The process only works sensibly in mode 12 if a grey tone set is selected (:GREYMAP), but similar monochrome shadings can be produced in other colours (:BLUEMAP, :REDMAP etc.). Mode 15 (and modes 20 and 21) give true colour shading.

MACROS

A macro allows an object defined on the screen to be saved for future use. The object can then be rescaled and rotated, and positioned as required. Thus a complete display can be created from a variety of separate building blocks, each created and saved separately.

REAL-TIME ANIMATION

The Real-Time Graphics Language is supplied as a module which you must load before use. This provides over 40 SYS calls (SWI calls for machine code programmers) which can be used in your own Basic programs. Silicon Vision also provide four demo programs on the disc. The SYS call format may be less familiar to many Basic programmers, but in practice provides simpler and more flexible parameter passing than, say, star commands.

The SYS calls in effect allow the selection of projection (viewpoint) and style of presentation to be changed continuously from within a program to produce an animated display. This has a lot of potential, and is the subject of further development by Silicon Vision in the form of a Film Maker package.

DOCUMENTATION

I am sure that any software package that is concerned with creating, editing and manipulating 3D objects will take much practice to use with ease. Thus the documentation has a vital part to play with any such product, particularly for those less used to 3D design.

The original manual is quite brief in its coverage of the software, but is now, fortunately, to be supplemented by a much more extensive tutorial manual with extra examples, as a result of feedback from existing users. This will be supplied as part of the package for all future purchasers, and existing purchasers who have registered with Silicon Vision will receive a copy free of charge. No copy was available at the time of wriring this review.

Silicon Vision also relies on a number of 'README' files on disc to document the latest features of the package. While this is an excellent way of ensuring that a purchaser has the latest software features (and information on their use), I feel that too much reliance has been put on this form of documentation. Even the inclusion of photo-copies of these files would make the information they contain more readily accessible.

The documentation of the Real-Time Graphics language (part of the original manual) gives no simple example programs to show how different SYS calls could be combined to produce worthwhile animation effects. Finally, many of the available keyboard commands appear only in a two page summary at the end of the manual (and many others don't appear at all). There is also, regretably, no index to the existing manual. The good news is that Silicon Vision says that a new version of this manual will be produced when current stocks are exhausted.

CONCLUSIONS

This software provides a powerful 3D modelling system, following as it does several year's of similar software development on the BBC micro. And I have certainly not mentioned all the facilities available. I do not feel however, admittedly on a relatively short trial, that the software is not quite as easy to use as it might be, and the lack of better examples on disc inhibits rather than encourages progress in the early stages of learning.

The documentation, which until now has been less than adequate, looks certain to be improved substantially in the very near future. This is good news for all users, as without better documentation, those new to 3D design in particular would find learning the use of the Real Time Solids Modeller harder than it need be.

The Real-Time Solids Modeller is certainly a powerful piece of software, which is set to reach a much wider audience with the advent of much improved documentation.
ProductReal Time Solids Modeller
SupplierSilicon Vision
 Signal House, Lyon Road,
 Harrow, Middx HA1 2AG.
 Tel. 01-422 2274, 01-861-2173
Price£89.95 inc. VAT
 (SolidCAD only £49.95, upgrade to Real Time Graphics Language £40.00)