Enum IfsFigure 

pub enum IfsFigure {
    Fern,
    Tree,
    Dragon,
    Sierpinski,
    Spiral,
}

Which curated figure the IFS draws.

A small closed set on purpose (ADR-0075). Twenty-four free affine coefficients with a contractivity cliff is close to unauthorable — most random tables are a blob or a diverging cloud — so the preset surface gets five hand-authored figures and a continuous path between them instead.

Variants

Fern

Barnsley’s fern — the canonical organic fractal.

Tree

Barnsley’s bare tree: a trunk that forks at ±45° all the way down.

Dragon

The Heighway dragon — two maps, and nothing organic about it.

Sierpinski

The Sierpinski triangle. Here as a correctness fixture as much as a look: its exact self-similarity makes a wrong implementation obvious at a glance, and it is the least organic thing in a plan whose brief was “organic” (ADR-0075).

Spiral

A logarithmic spiral arm with two satellite maps.

Implementations

impl IfsFigure

pub const ALL: [Self; 5]

Every curated figure, for the sweeps that must cover the whole roster.

A named constant rather than a literal at each call site: the safety argument is a sweep property (max σ < 1 for every figure, every pair, every lever extreme), and a test that iterates a hand-written list is one forgotten entry away from proving it about four of five figures.

pub fn from_name(name: &str) -> Option<Self>

Parse a [particles] family name, or None if unknown.

pub fn name(self) -> &'static str

The [particles] family name this figure parses from — the inverse of from_name, for diagnostics and for the round-trip test that keeps the two in step.

pub fn table(self) -> IfsTable

The curated table, decomposed — the form everything downstream works in.

pub fn frame(self) -> (f32, [f32; 3])

(world scale, centre) — the projection’s framing for this figure at the reference aspect, as a fallback.

The render path takes its framing from FitLut instead, which follows the morph and knows the target’s aspect. This survives for the two callers that have neither: the seeded scatter, and the CPU transcription of the draw shader that the projection tests run.

The fern is the reason Basis::projection carries a full three-component centre rather than a z-centre: it spans y ∈ [0, 10] and is not origin-centred, so a projection that subtracts nothing puts its root on the bottom edge and its canopy off the top.

pub fn seed_box(self) -> ([f32; 3], [f32; 3])

The seeded initial-scatter box, (half-spread, centre) per axis.

The figure’s own bounding box, so the initial fill lands over the attractor and converges onto it rather than travelling to it. The probability-weighted per-step contraction is 0.742 for the fern, so a displacement shrinks a thousandfold in ~23 steps — 0.39 s at the fixed step, which is the startup haze ADR-0075 records and the successor plan’s staggered respawn removes.

z is zero: the family is two-dimensional and takes the default Basis::XY.

pub fn packed(self) -> IfsPacked

Resolve this figure to the compute step’s payload.

Phases 3–5 grow this into resolve(a, b, morph, levers), which is where the whole safety argument lives — and it stays a pure function with no GPU and no clock, so a sweep asserting max σ < 1 over every figure pair and every lever extreme is an ordinary unit test.

Trait Implementations

impl Clone for IfsFigure

fn clone(&self) -> IfsFigure

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for IfsFigure

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for IfsFigure

fn eq(&self, other: &IfsFigure) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for IfsFigure

impl Eq for IfsFigure

impl StructuralPartialEq for IfsFigure