Struct ScumCtx 

pub struct ScumCtx<'v> { /* private fields */ }

Column-edit batch context. Construct via ScumCtx::new after calling Vxl::reserve_edit_capacity on the world.

Holds a &mut Vxl borrow plus the rolling 3-row b2 buffer cache. Mutate columns via ScumCtx::scum2 — it returns the b2 buffer for the requested column; mutate via delslab / insslab. Edits are committed when the y row advances (or when ScumCtx::finish drains the last 2 rows).

Caller MUST invoke ScumCtx::finish explicitly. Drop without finish leaks the trailing 2 rows of edits — voxlap’s contract.

Implementations

impl<'v> ScumCtx<'v>

pub fn new(vxl: &'v mut Vxl) -> Self

Open a new column-edit batch on a Vxl. The Vxl MUST have been upgraded with Vxl::reserve_edit_capacity beforehand (the slab allocator must be initialised).

Panics

Panics if vxl.vbit is empty (no edit capacity reserved).

pub fn set_colfunc<F>(&mut self, f: F)

where F: FnMut(i32, i32, i32) -> i32 + 'v,

Install the color callback. Voxlap’s vx5.colfunc. Called for each newly-exposed voxel produced by edits.

pub fn scum2(&mut self, x: i32, y: i32) -> Option<&mut [i32]>

Open column (x, y) for editing; returns its b2 buffer. Caller mutates via delslab / insslab.

Auto-flushes any prior y row that’s no longer in the rolling window. Returns None if (x, y) is out of world bounds.

pub fn with_column<F>(&mut self, x: i32, y: i32, f: F) -> bool

where F: FnOnce(&mut [i32]),

Edit one column with closure-based access. If (x, y) matches the immediately-previous successful ScumCtx::scum2 / with_column call, reuses the cached b2 buffer in radar (skipping the redundant expandrle that would wipe pending edits). Otherwise calls scum2 to load the column.

This is the primary edit API for span-style batch operations where multiple z ranges land on the same column — set_spans is a thin wrapper. Returns false and skips the closure if (x, y) is out of world bounds.

pub fn finish(self)

Drain the last 2 rows and consume the context. MUST be called — Drop does not auto-finish (voxlap contract).