Effector

Effector is for writing your own effector in VEX, when none of the built-in ones gives the direction you need. The built-in effectors are made the same way, so once your node is in the scene it appears in the effector picker of a Grow or Assembly Decoration like any other, and works with every response mode. Effectors covers how effectors are read.

Writing the snippet

VEXpression runs over the points of the growing skeleton. Write a vector attribute there and list its name under Export. The names listed there are the directions an effector row can pick, and one Effector can export more than one.

When the tree grows, every effector runs in one pass, so the snippet is given a string, geo, holding the group of this effector's own points. Use it in every lookup on the effector's geometry, or the snippet will read the points of other effectors too. The first input takes the effectors upstream of this one and passes them through. Geometry wired into the second input travels with the effector, so the snippet can read it, for example curves to steer toward.

As in an Attribute Wrangle, the button beside VEXpression adds a slider for each ch() call in the snippet. icon sets the icon the effector shows in effector lists.

The built-in effectors are written the same way, and their code opens with a note inviting you to read, learn from and adapt it. Gravity Effector is the shortest, and Magnet Effector shows lookups on wired geometry. VEX has more on writing effectors.

Status

Effector is experimental, and the way effectors are written may change.