Utility

Plumbing: pick a channel, switch a branch on or off.

2 ops: pick-channel, switch.

Ops with no demo image below produce no visible result on their own — they feed other nodes rather than paint.

pick-channel

Extract a single channel of an RGBA raster as a [0, 1] ScalarField. RGB channels are read in non-premultiplied space; luminance is Rec. 601 luma over the non-premultiplied colour. Bridges the raster pipeline into scalar-field ops (map-range, threshold, color-ramp).

Field	Type	Required	Description
channel	r | g | b | a | luminance | $param	no	—
input	@node	yes	Reference to another node (@name).

switch

Pass one of its inputs through. By condition, as MapLibre’s case: the first of cases whose when holds, else default. By name, as MapLibre’s match: branches maps names to nodes and select names one, with default for a name no branch has. The two-way form, a / b picked by select, is deprecated: it still works, and the build warns with the cases (or, for a string param, branches) form that does the same. Inputs accept any port kind. A choice fixed by literals is made when the graph is built, and the output mirrors the chosen input’s kind — so branches may be different kinds. A $param or @node choice is made per render instead, which requires every branch to be the same kind. Only the chosen branch is rendered; a @node when is known only once evaluated, so every branch from the first one on is rendered with it.

Field	Type	Required	Description
a	@node	no	Deprecated: use cases, with this as default. The branch taken when select is false or absent.
b	@node	no	Deprecated: use cases, with this as the then of a case whose when is select. The branch taken when select is true.
branches	object	no	Name → node; select names the one to take. A $param select must be a string param, and each value its enum allows must name a branch unless there is a default.
cases	array of object	no	Tried in order; the first whose when holds is taken. Needs default.
default	@node	no	Reference to another node (@name).
select	string | $param | @node	no	With branches: the name of the branch to take, or a string $param naming it, read per render. With the deprecated a / b: "a" (the default) or "b", a bool $param or @node port (true picks b), or a string $param naming a or b — write a bool choice as cases, and a string param as branches named a and b.