So far, the shape of your 3D tree was based on genetics. Now it’s time to add a second influence: the environment it grows in. With React you can set up an environment to attract, deflect or stop new growth. Avoid buildings, simulate a dominant wind direction and grow inside a shape.
There are several ways in which a tree reacts to its environment:
You can combine multiple types of react objects to simulate many effects.
This is a good place to clear a common misconception. Plants do not grow toward direct sunlight. If they would, they would all lean south. They would soon lose balance, gravity would not be in their favor. Plants bend only to indirect sunlight, the light bouncing around the sky all around us. It is the blue color that a plant senses and loves.
Use the 4 pickers to pick objects for each reaction type – Block, Attract, Deflect and Shade. A simple mesh object with just several polygons can have a striking effect. Or use the stylized shape of a building to avoid it. Use complex shapes to create a topiary.
The Attract and Deflect interaction types have a Radius of influence. When a branch grows within this proximity, it gets influenced by the environment. The closer it gets, the more powerful this effect becomes. The Strength parameter multiplies this influence.
Environments are not static. Surrounding trees come and go, changing the tree’s exposure to light and wind. Try enabling interaction for just the last years, to simulate a windswept tree.