Describes: adding metaquadrics, setting strength and repulsion, polygonizing, adding fur.
Start Tornado3D or open a new project replacing the existing one with Project> New. We'll model a Teddy Bear with Metaquadrics.
Add an implicit object with Objects> Implicit> Add Item. This opens MetaQuadric Panel, accept the defaults to add a shape that resembles a sphere. Select it and with Copy and Paste create three copies displacing them like in figure. The central sphere needs to be rescaled because it will become the bear's head, while the two upper spheres will become its ears and the front one its nose.
The Teddy Bear head built with MetaQuadrics
The spheres can not yet fuse because they are not grouped. Select the head, then multiselect the other three spheres then group them with Amiga-G. Now the first selected sphere has become the father of the hierarchy and also controls the surface properties for the resulting im plicit object. Switch to preview modes Realistic or Photore alistic to fully appreciate the fusing surfaces.
While modeling with implicit objects, unset Smooth for their surfaces. This will speed up preview a lot even on the fastest processors.
Even with just those four spheres the shape already resembles that of an animal's head but the biggest draw back are the spherical ears. Ungroup the hierarchy with Amiga-Y and deselect everything with the space bar. Now multiselect just the two upper spheres and scale them along Z axis shrinking them until they look like two flat tened spheres. This is a great advantage with respect to simpler metaballs-only softwares: items can be scaled, stretched, even deformed and still are able to fuse retaining their basic shape.
Negative strength forces items to repel one each other
To create the concave depression inside the ears, copy and paste any sphere then move it just in front of one of the rescaled ears. With Objects> Implicit> Panel open the Implicit Panel and change its Strength from 1.0 to -1.5, thus turning it into a negative magnet that repels other spheres.
Copy this new sphere and paste it in front of the other ear, then group all the spheres to see how they look like when fused.
Two negative spheres provide dented ears
Add yet another implicit item, this time changing the Y size from within Metaquadric Panel creating an elon gated sphere of sorts that will become the body of our bear. Move this item below the head and try grouping all spheres to see how they fuse. This will probably require a few tries before a nice fused "neck" appears in preview.
The items are always shown as spheres, but notice how the Y axis is enlarged
By now we should be familiar with adding, grouping and ungrouping those clay balls, so add another five new items, that will serve as the arms, the legs and a bulge to simulate a fat teddy bear. The new spheres will have to be rescaled, so as usual rescale them before grouping other wise an ungroup will be needed every time an item has to be resized. Rearranging the new spheres the result should be similar to the one in figure and will already look a lot like a teddy bear.
The arrows mark the newly added spheres
Now the basic geometry is complete. Metaquadrics make organic modeling a snap, and shapes that would have required hours of work can be completed in minutes. Save the group to disk before proceeding.
Select the group and with Amiga-I open the Object Info panel. Change the detail level keeping it low, for example 25, to avoid creating too many polygons. Then, with Objects> Implicit> Compute Shape, create a polygonal model from the implicit definition. This is needed because the Hair generator needs polygons as a reference.
To complete the model, add eyes and the nose. Those are just polygonal spheres, scaled and placed approxi mately near the polygonized bear's surface. No need to be accurate, it's a teddy bear after all.
The arrow marks the eye and nose spheres
Assign materials to the objects the way you prefer, a middle brown tint with Granite texture is suitable for the body, while the eyes should be shiny white and the nose of a darker brown. Group the objects keeping the polygonal bear as the father and save this object to disk.
Now fur has to be added. This is made easy by the Hair Generator and the Furry Particles it creates. Select the bear and use Objects> Particle> Hair to open Hair Genera tor panel.
Hair Generator adds thin lines over polygonal surfaces
We can leave the values at their defaults, but since the bear will probably be composed of many polygons we have to lower the number of Hairs per face to 1 or 2 and the number of Hair segments to 2. If the number of faces in original object exceeds the maximum allowed, Hair Gen erator will simply quit without performing any change. Accept the panel and a new object will be added to the scene, with all sorts of furry particles located in space over the bear's surface.
The furry particles appear to grow over the original object's surface
The fur can now be textured with a lighter color similar to the bear skin's one, and a rendering is in order. Just like soft particles, Hair Particles are of fixed size and do not adapt to screen resolution, so a few experiments are needed to find the optimal size that can be set with the Min Size gadget in Particles Panel.