strip

Surfaces laid along curves. geometry.ribbon lays a flat ribbon of a width along every curve of a geometry, lying square to up. It is what a crack glowing in the ground, a trail, a beam, a tyre mark or a road is drawn with.

Each edge of a ribbon carries every attribute of the curve point it was laid from, so a field or a material reads generation, heat or anything the curve carries across the ribbon. The mesh's uv is laid for a shader:

• uv.x runs 0 to 1 along each curve, by distance;
• uv.y runs 0 to 1 across it, so a hot core down the middle and a soft edge come from uv.y alone.

Width can change along a ribbon:

• taper narrows each ribbon toward its end, the way a crack thins to its tip;
• widthBy names a Float point attribute that scales the width where the points carry it — for example a branch's width from its generation through a ramp, or a trail thinning with age.

lift raises the ribbon off its curve along up, so one laid on a surface draws above it.

procgen.searchNodes("", { pack = "strip" }) lists the family and procgen.describeNode("op.<id>") describes any one of them.

local line = g.op.curve.line({ start = { x = -1, y = 0, z = 0 }, finish = { x = 1, y = 0, z = 0 }, segments = 8 })
local cracks = g.op.curve.branch({ curve = line, generations = 3, branches = 2, normal = { x = 0, y = 1, z = 0 } })
return { glow = g.op.geometry.ribbon({ curve = cracks, width = 0.05, taper = 0.9, lift = 0.004 }) }