Tree and grass

Tree and leaves generation

The MakeTree macro (maketree.zip) creates "realistic" trees through a recursive algorithm. The tree structure is defined by parameters passed to the macro. Many tree and bush shapes are possible (with some exceptions, like cone-shaped trees or palm-trees). This macro was used in The cliff and, in a slight different form, in Harvest time.
The trees can have leaves or be leafless (MakeLeaf, a leaf generating macro, is bundled with MakeTree), they can have roots or be rootless, they can be more or less gnarled, and their shape can be modified by the application of a force, such as wind or gravity. A random seed enables the generation of an infinite number of trees based on the same set of shape parameters.
Examples of trees and leaves are given.
The tree, leaf and foliage objects can be saved as include files for later use.

Some trees made with the MakeTree macro

Links to other 3D tree resources:

Those who don't want to use a parameter-based tree generator can have a look at Tree designer by Johannes Hubert, an excellent interactive tree modeller (shareware).
Tomtree is a very complete tree macro by Tom Aust. Many tree types are supported (including palm-trees) and it gives very realistic results.
SplineTree is a tree macro by Andrew Clinton, very natural-looking. It supports less tree types than TomTree but you can have flowers.
For the lazy, here are a few trees in 3DS format.
For the rich and lazy, OnyxTree is a library of ready-made trees based on real ones (commercial).
Amap Genesis is modeler of vegetation that is true to life and which is based on a unique methodology for vegetation growth simulation (commercial).

The MakeGrass macro (mgrass.zip) generates a square patch of grass of a given size and density. Each blade is independently created with its own length and curvature. A similar algorithm was used for Migrants.
The patches can then be assembled into a prairie.
2 examples are given.
The patch mesh can be saved as an include file for later use.