Foliage mode

FoliageMode is the fourth viewport mode. It claims the foliage command context, puts six tools on 1–6, and hands every pointer gesture to FoliageEdit — which owns the volume, the palette selection and the drag in flight.

Painting trees, rocks and props onto whatever is there. You want it whenever the things being placed have identity; a rule-driven carpet of grass is the other tool, and it changes a rule rather than instances.

⚠ It requires nothing, and that is what makes it a separate mode from terrain's. Sculpt and paint need a terrain and act on its texels; foliage paints onto any surface, and its filter set is the feature. One mode that did both would answer "what is the target surface" twice with different answers.

⚠ The digits are slots, not named tools — TerrainMode's rule, for the same reason. Blockout claims 1–4, terrain 1–8 and foliage 1–6, all in different contexts, and view-bookmark recall keeps all nine everywhere none of them has the focus.

⚠ An empty palette shows the palette, not an empty strip. The two tools that act on what is already there — select and erase — stay reachable; the four that place things are greyed, and FoliageEdit.Refusal is the sentence the panel shows instead.

⚠ Every surface filter off is refused rather than silently landing nowhere. A brush that does nothing and says nothing is the version reported as broken.

⚠ The tool to get right, and it is Unreal's. It is what turns foliage from place-and-regret into an editable thing: changing a type's scale range afterwards should re-roll the scale of existing trees without moving them, and re-rolling everything is not the same operation. FoliageReapply is a checkbox per property, which is exactly how Unreal does it.

⚠ The position is never re-rolled. That is what would move a forest somebody had already thinned by hand — so it is not one of the flags.

⚠ The filter pass is its own flag, because it removes things. An artist tightening a slope range expects to be asked before a third of their forest disappears.

⚠ A foliage stroke's record is instances, not a rectangle. Sculpt and paint both write a grid, so their records are a rect of values; this writes a list, so what it holds is what it added and what it took away.

⚠ Redo re-adds rather than re-scattering. The scatter is deterministic from its seed, so re-running it would produce the same trees — but only if nothing else changed in between, and an undo stack does not promise that. Somebody who erased a clearing, undid it, then undid the stroke before it has changed what the spacing rejection sees.

⚠ Addresses do not survive the round trip, and the command does not pretend they do. Undoing removes what the stroke added, which shifts every index after it. The command works in instances and the editor re-resolves its selection after any edit.

⚠ A move across a cell boundary re-cells the instance, so its address changes — and a gizmo still holding the old one would move a different tree on the next drag, which reads as the gizmo drifting. FoliageMoveCommand hands the new addresses back after each apply.

⚠ The selection survives leaving the mode; a half-painted stroke does not. A stroke belongs to a gesture that is over; a selection is a statement about which trees somebody is working on, and losing it on a trip to the outliner is the version people complain about.

A stroke driven from world points, which is what a test does and what the pane does with a ray:

Re-rolling the scale of a wood after widening its range:

Picking one out and lifting it:

Removing a palette entry is registered as unavailable with the reason rather than left absent: it renumbers every index above it in the chunks, the selection and every undo entry on the stack. The .vxfoliage importer is the same owed item .vxlayer has — this is the content and the form, and turning either into a file belongs with Vixen.Editor.Assets.

• Editor modes — the seam this is the fourth consumer of.
• Sculpt and paint mode — the other one, and why they are two.
• Foliage instances — the kernel behind every tool here.
• docs/plan/31 § T5 — the phase this is, and its exit criterion.