Trees that split into two parts as they grow upward are common in nature. In SpeedTree Branch Generators can add a configurable split to add realism to your tree models
Note: In older versions of SpeedTree, there was a similar feature called “bifurcation.” That term is still used in SpeedTree 8 but means something else. See Bifurcation for its current meaning.
You'll do your editing for splits between two generators. The starting generator, for example a trunk, will be the control for whether or not there are splits. The generator that follows (as an extension of the parent) is where the new post-split branches are placed.
Step 1: Click the generation level that will start the split.
Step 2: Edit the "Skin:Splits:Chance" property to increase the likelihood of a split.
Step 3: In the generator that is splitting, make sure "Extend Parent" is enabled.
Step 4: Edit the other "Splits" properties to control the actual split geometry. You can control the thickness of the splitting branches, the balance between them, and the smoothness of the “crease.”
When you split a branch, the texture wrapping around it must also split cleanly. This means your U tiling must be divisible by two, so it can accommodate being halved. For example, if your trunk has UVs that tile twice in the U direction, each of the splits will then be able to tile once.
For more information on editing branch UVs, please see the UV Mapping section of the Branch Generator.
In the “Extend Parent” property, there are options to extend one side of the split and not the other. This allows you to have entirely different style branches growing off of either side of the split.