Run the TreeGen script. The following requester will appear:

1. Trunk width

This setting determines the width of the trunk on the ground level. It's suggested that you use real world scale when setting up TreeGen.

2. Sides

This determines the base resolution of the tree trunk mesh (before subdivision). Use caution with the setting - there's a potential to make a very dense mesh if this is set high.

3. Segments

This sets the number of segments in the tree trunk between each iteration. You can have a rough idea of the resulting tree height by multiplying the number of  Segments, Segment length and iterations together.

4. Segment length

This determines the length of each segment.

5. Segment shrink

This setting is used to adjust the relative thickness between the root of the tree and the branches. Higher settings will create thinner branches, and setting of 0 will make the branch thickness equal to the root thickness (blocky look i might add ;-).

6. Branching

This sets the number of new brances created in each iteration. If the setting is 3 or higher, a random number between 2 and the setting is used in each iteration process - so, with setting of 5, you will have 2 to 5 new branches / iteration.

7. Branching mode

"Spawn" will make the branches grow from continuous tree trunk, "Divide" will split the trunk with each iteration.

8. Iterations

When talking about TreeGen, an iteration means dividing the trunk, or growing new branches from it. Higher numbers look better, but will create a very dense mesh.

9. Spread

This setting controls the "fatness" of the tree shape. Small numbers will create skinny trees, big number will result in more bush like appearance.

10. Trunk <> Branches (Bias)

This setting controls the overall appearance of the tree. Low values will have emphasis on the trunk, high values on the branches.

11. Shape variation

This is a curvyness / straightness setting for the tree. The bigger the number, the more jitterburg in the tree shape.

12. Subdivide tree mesh

As the name states, you can use this setting to subdivide a rough tree shape to more closeup friendly appearance ;-)

13. Leave clusters

"Polys" will create an individual polygon for each leaf. Looks nice, but watch that polycount ;-) Almost identical results can be obtained when using "Clusters", and setting up a transparency or clip map texture for the leaves, with less rendering overhead. "Blob" will create just one big clump of leaves - usefull for low-rez background trees.

Using veins as the clip / transparency texture for the leave clusters has proven to be quite succesfull. At later point, i will try to add a feature to TreeGen, which can apply these. For now, you will just have to settle for texture presets...

14. Leave cluster size

As it says -

15. Leave cluster resolution

The leave clusters are actually tessellated spheres, copied to the tip of each branch. This setting controls the tessellation level of the clusters.

16. leave cluster randomness

Setting of 0 will give you beautiful, perfect spheres as your leave clusters. I dunno if there's a tree like this in real world though ;-) The higher the setting, the more the clusters are displaced.

17. Leave poly size

This only functions if cluster type is set to Polys. The control is used to scale the individual leaves.

18 Leave jitter mode

This is a setting that can affect the look of the leaves quite strongly. I suggest you just experiment with different settings with this, as well as leave cluster randomness and poly size. Have fun!

19. Reset settings

Resets the settings to factory defaults. Use this if your trees look really weird, and you can't locate what setting is the one causing troubles...

For technical help (Also for ModPak users!!), there is also a mailing list for the PlugPak users.