Foliage & Instancing

The canopy is what reads as a tree from a distance: the leafy mass, its density and its silhouette. In Natsura the canopy is placed onto the skeleton as a decoration, after the tree has grown, and it is placed as instances. A canopy can hold hundreds of thousands of leaves, so what you place are copies of a small library of parts, and Natsura keeps them instanced through placement, posing and export.

Assemblies

An assembly is a prefabricated branch or leaf cluster, rigged so it can be deformed, and made of instanced pieces. You prepare a library of them with an Assembly Resource, which imports a kit of parts, checks their pivots, rigs them and assigns materials. The Assembly Decoration then places them on the tree. This is the main way to build foliage. See the Assembly Workflow.

Two other routes feed into it or sit beside it. The Atlas Workflow turns 2D leaf atlases into parts. The Clusters Decoration fits parts along the branches, bending each one to follow its branch.

Building a canopy

The Assembly Decoration does most of the work, and each of these is one of its controls.

Spawn at decides where parts go: Tips (the default), Intersections, Internodes or Roots, in any combination. Tips give a sparse outer layer, and Internodes fill the branches for a fuller crown. Mask thins the placement, and like most values on the decoration it can be mapped from an attribute.

Traits decide which part goes where. A trait is an attribute that lives in two places, on the parts and on the skeleton, such as height, u, the angle of a branch (elevation_angle) or age, or an attribute you gave the tree's source point. The decoration places each part where the tree's traits match its own, so the canopy changes across the tree instead of repeating one part. Press Enter on the decoration to arrange the parts on the trait chart. See Trait System.

Effectors pose the parts. Because the parts are rigged, an effector bends each one through its rig, such as laying the leafy ends flat to the sky, and the parts stay instances. See Posing the parts.

Prune thins the result. It removes pieces from inside the placed parts, not whole parts, and it removes the most where the canopy is densest, so the canopy opens up in a more natural way than with Mask alone. Mapping the Mask as well lets you keep more on the outside of the crown and thin more on the inside.

Bigger parts from smaller ones

A canopy doesn't have to be built from single leaves. You can grow a branch in its own Simulate, decorate it with assemblies, then turn it into an assembly library with Rig to Assembly and place that on the main tree. Larger parts mean fewer placements for the same canopy. See Rig to Assembly.

Instancing through to export

The same library parts are reused across the canopy, and posing them through their rigs doesn't make new geometry, so the canopy keeps the memory and render cost of instances. The instancing carries through the export to Unreal as Nanite Skeletal Assemblies. See Take Your Tree to Unreal.

Related

• Trunks & Meshing, the decorations that mesh the rest of the tree.
• Materials, how the parts are shaded.