Both components belong to the group of components that influence the global shape of a plant. With both, a freeform deformation (FFD) can be defined that works either on the geometric data or only on the underlying shoot axes.
Two types of deformation definitions are utilized. While the FFD component functions Dx(x), Dy (y) and Dz (z) must be entered by the user, the hyperpatch component works with a three-dimensional Bezier function of degree one to three. This in turn defines a cube with a sequence of control points that can be moved by the user. An adequate graphical interface allows for the direct manipulative interaction.
Furthermore, the components can also be utilized as a switch to interrupt the influences of a preceding deformation. In this case, no deformation is specified, but rather a special parameter is defined to switch off the process. This way, an FFD can be defined in the p-graph at one place, while the effect on the child components can be voided at another place. In Sect. 6.5, this is explained in more depth and demonstrated with an example showing the difference between the deformation of the geometry and the shoot axes.
The positioning of all geometries, and especially the positioning of leaf and tree components, can be influenced by photo – and gravitropism. These work relative to the light and to the gravitational field. The light field by default comes from the vertical direction, the gravitational field by default points in the opposite direction.
Using the component, this field can be arbitrarily redefined, in that for the x-, y – and z-components of the directional vector a spatial function is specified. The range of possible applications for these fields is numerous, as will be shown in the following examples.