TrueSpace has always led the pack in terms of features as far as Windows 3D animation packages under $2,000 are concerned. Recently, however, the market has become rather crowded, with a powerful upgrade to Ray Dream (reviewed issue 9, p100) and the cut-down version of LightWave 3D (Inspire 3D) both challenging it on features and price. Version 4 strikes back, building on the products good reputation with a host of power-ups that will make it an attractive prospect for the professional 3D animator.

TrueSpace offers a different approach to most applications for 3D modelling. The majority of 3D packages take their lead from computer-aided design: models are created using cross-sections that are spun around an axis or extruded a certain distance to define an objects surface.

Although TrueSpace can operate in this fashion, the focus is more on deforming objects into the required shape as if kneading clay. This tactile sense has been greatly enhanced in version 4 by the inclusion of NURBS objects (non-uniform rational b-splines), which is something no other application in this price range, other than Inspire 3D, is capable of.

The principles behind NURBS are that a simple set of polygons defines an underlying object, the vertices of which are Bezier control points for the curved vertices of the polygons beneath. The object surface isnt made of flat polygons, however. Instead, the polygon mesh of a NURBS model is smooth and realistic looking. This would be less useful if it wasnt for the fact that TrueSpace is well endowed with real-time textured preview modes. Traditionally, the program used 3DR, with very few graphics cards accelerated - only the Matrox Millennium at the last count. Version 3 added Direct3D support, although it was a little flaky; OpenGL was added in the 3.2 update and is fully fleshed-out here in version 4. Either way, the chances are that a reasonably recent machine will have some form of hardware-accelerated preview available.

Inverse Kinematics (IK) were added in version 3, a necessity for character animation of limbed figures. This allows you to create joints that behave naturally and are easy to animate. Instead of having to animate a limb starting from the point of contact with the body, IK lets you grab its end point and move that instead; the other joints in the limb follow naturally. However, in TrueSpace 3 the IK capabilities were best applied to limbed machines such as robots, since organic creatures have flesh that flexes as limbs move.

To simulate this, TrueSpace 4 allows you to stretch a polygonal skin over IK bones which then flexes realistically. You can either extract the IK chain from an existing model, or create a bare chain, which becomes the skeleton of the model. Add a surface skin with tendon, muscle or contractor properties and you have a model that flexes and animates incredibly realistically.
TrueSpace 3 also marked the debut of the applications physical simulation capabilities. These allowed you to give objects physical properties, like paper or glass, which defined how theyd bounce on collision and how natural effects such as airflow would influence motion.

Gravity and velocity could also be added to the equation and the results recorded. TrueSpace 4 extends this idea with full collision detection, a feature that allows you to make objects dense so that when they collide they either stop or stick together. This makes it easy, for example, to place a chair in a room. Instead of risking the chair either hovering slightly above or penetrating the ground, you can be sure it abuts the surface exactly.

TrueSpace 4 now introduces scripting functionality, using the Python language. Although this is intended to help you create custom effects you can reuse, I found it a little more opaque than a simple macro recording facility, which would have been easier to use and generally more useful. However, the scripting is potentially powerful, and Caligari claims you could use it to prototype game behaviour.

A related area is the animation timeline. TrueSpace 2 had an inferior animation timeline, even when compared with lower end competition, and TrueSpace 3 wasnt much better. TrueSpace 4, on the other hand, is much improved. You can now expand the timeline for each object to include each animated characteristic, move keyframes manually and even apply function curves.

Shading and texturing capabilities have also been beefed up in TrueSpace 4. Earlier versions sported a range of customisable procedural textures but complicated layered surfaces werent possible. This all changes in version 4. You can still apply the traditional textures or, alternatively, you can build your own from four basic components. These define colour, reflectivity, transparency and bump mapping. A variety of shaders can be loaded into each of these four, and the colour component can be made up of eight layered textures, combining bitmap and procedural surfaces. Using a transparency variable, you can vary how much of each layer shows through the others to create all manner of interesting effects. TrueSpaces surfacing abilities have long lagged behind software that was, in other respects, less fully featured. Its now on a par with the best, offering plenty of flexibility. Unfortunately, the 3D paint tools introduced in version 3 are still very slow compared with dedicated 3D paint utilities like MetaCreations Painter 3D. Its not possible to paint over existing textures, forcing you to remove them from an object - a procedure that isnt explained in the help file or manual.

The biggest failure of earlier versions of TrueSpace, however, was in its rendering capabilities a common problem with lower-end software. Although TrueSpace had a ray-trace renderer, it was extremely slow and still failed to produce realistic output. Fortunately, theres a new renderer in TrueSpace 4, courtesy of Lightworks Design, that supports radiosity and volumetric lighting. Radiosity is where objects that are obscured from direct light rays are still lit by the reflections of the surrounding objects. Volumetric lighting is a way of calculating shadows and fog that takes account of the true volume of space between objects, producing extremely realistic-looking effects.

For example, instead of creating fog that pays no attention to the varying distance between the camera and different objects in a scene, volumetric lighting factors this into the equation. Add the renderers support for anisotropic shaders, which reflect light with a different colour depending on the angle of reflection, and the result is an image quality much more impressive than before.

Of course, these new effects can have a major effect on rendering speed. The renderer is now multithreaded to counter this, so that a multiprocessor machine running Windows NT will output a scene more quickly. In our tests, the same render on a single Pentium II/400 and a dual-Pentium II/333, both with 128Mb of RAM, took 63 seconds and 58 seconds respectively. That isnt a massive improvement from two CPUs, but its still worth having. Sadly, Caligari hasnt gone the whole hog and created a network rendering module. This prevents it from competing with higher-end applications. But since the application is essentially aimed at the solitary 3D artist, the omission shouldnt put off too many potential buyers.

Other than that, theres very little missing from the TrueSpace 4 feature set. With software as complicated as this, the biggest factor beyond the range of features is the interface. Like the majority of PC 3D software, TrueSpace originates from another platform the Commodore Amiga in this case so the interface can be hard to navigate if you forget where a certain feature resides. This is true of all 3D animation software, however, which can be a complex activity at the best of times. Caligari has improved matters with context-sensitive menus