Prune

Prune tests a condition on each branch while the tree grows, and keeps testing it for a number of cycles.

Where it goes

A Prune goes into a Grow's third input, Graph - Prune. With a Grow selected, the Prune tool on the Natsura toolbar (under Advanced) wires one in there.

The condition

Use Expression picks how the test is written, Threshold or Expression.

Threshold compares Compare Attribute, using an operator (>= by default), with Test Value (0.5 by default) or with Test Attribute. Compare Attribute is empty on a new Prune, and its menu and Test Attribute's list nothing, so type the attribute names. The attributes the tree carries are listed on the Wrangle page. To prune on something they don't carry, such as exposure or crowding, write it as an attribute in a Wrangle and test that.

Expression shows Prune Snippet, a line of VEX such as f@height>5 (the default).

Timing

Start Delay is how many steps a branch grows before testing begins (1 by default). Test Lifetime is how many times the condition is tested again for each internode (5 by default).

Related

For forks, Split, Switch and Kill, see Forks, Split, Switch or Kill.

Prune Wizard (Experimental, on the toolbar under Advanced) is a different node: a post-process for removal that takes an Assembly, rather than a step in growth.

Pruning on Assembly Decoration is a different thing again: it thins out placed parts after they are in position.

Status

Prune is experimental, and its settings may change.