Product Reviews

CAD software has two purposes: the production of accurately-dimensioned and annotated 2D working drawings, and the construction of 3D models for visualisation. Many packages concentrate on one of these areas while others combine them, but TurboCAD 2D/3D resolves the dilemma by providing two applications in one box.

This seems generous until you realise the whole package is expected to sell for around £150, making it either the best bargain in CAD software or disconcertingly cheap.

TurboCAD, the drafting program, and TurboCAD 3D, its modelling companion, aren't linked. They don't even share a file format, so files saved in TurboCAD must be passed through a converter to make them readable by TurboCAD 3D. The developer, IMSI, said separating the 2D package from the 3D package makes it more efficient, but as the programs are likely to be integrated in the future, the benefits seems dubious.

TurboCAD's interface and behaviour is very un-Mac-like. The menus and menu bar are blue, and the arrow cursor is replaced by full-screen crosshairs. There are nine palettes, and all operations involve first choosing a tool or menu. Selecting an object involves a trip to the Select Object menu item and clicking on the object. Even deleting an object requires the delete object tool. This is so inconsistent with the Mac way of working that it's constantly confusing. The absence of a standard cursor is disturbing too, and the whole interface has an early CAD workstation feel.

The drawing and snap tools provide a powerful range of options, including smart dimensioning, but there is no support for Bezier curves, which is a drawback for anyone who comes from a graphics background. Multiple copies of an element can be altered by editing one copy and applying it universally. Multiple drawing layers and object classes are also supported. Export and import options include DXF, which appears to be a very clean implementation of the standard. There was no problem saving multi-layered DXF files, which were perfectly legible by AutoCAD and other CAD programs. The only catch was the time it took to export.

TurboCAD allows you to extrude or revolve a shape to create a 3D object which can be

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viewed in elevation, isometric and perspective. However, all constructions are wireframe only and can't be rendered by TurboCAD 3D to look solid.

There are over 100Mb of 2D and 3D symbol libraries included on the installation CD, with even more which can be unlocked once you've paid over the phone. The libraries are very comprehensive and you can get a long way without drawing a line.

TurboCAD 3D could not be more different from its drafting companion and there are some nice touches which more expensive modellers would do well to implement.

The standard drawing window consists of four views: top, front, side and perspective. All have a grid showing the cursor location in 3D, and all are updated simultaneously. You can construct in any view, including perspective, by choosing 2D or 3D shapes from the tool palette. Modelling from scratch in perspective is quite difficult, but the feedback on the grid and the cursor height made it bearable. There are rotation arrows around the perspective view for turning the model, and an angle of view arc which you can drag to alter the perspective.

A useful feature is the facility to include up to 16 layers. By placing elements of your model on different layers, you can work on one part without affecting the others.

The rendering engine is very fast and produces flat colour with dark facets to show shading and light facets to show highlights, but the result is enough to provide an impression of solidity, and the semi-transparency option allows you to see through foreground elements and windows. TurboCAD 3D is unusual in that the model can be viewed from any angle with layers shown or hidden, without more rendering.

TurboCAD 3D also provides two interesting animation facilities, allowing you to create fly-throughs of your rendered model. The first, Simulation, records a series of chosen key frames and generates the in-between frames to provide smooth movement. This animation is saved as a series of instructions and created on the fly every time you play it, which can be slow and jerky. The other option, High Speed Film (HSF), produces a rendered animation capable of up to 30fps playback from a Simulation file. Using the converter supplied, you can make a QuickTime movie of this HSF file to use in presentations. However, the HSF rendering can take many hours.

TurboCAD contains everything you need for most drafting requirements, but its usability is suspect. It started life as a PC program and is unable to hide its roots. Compared to MiniCAD, its nearest rival, its only major selling point is price. The program is easy to use, and its animation facilities are excellent. Butit's let down by an old-style renderer, and IMSI should look at the benefits QuickDraw 3D has brought to other Mac packages.