Simple mode

Live tessellation

Place a shape on every face of a surface and bend it to fit — then go on adjusting the count, the height, the twist and the taper as long as you like. This is the engine behind nine of the effects, and the one most people spend the most time in.

Setting it up

01
Have a base and a component
The base is the surface being covered. The component is the shape being repeated. Both can come from the library, or either can be your own mesh.
02
Select the base
The base must be the active object. This trips people up constantly: if you add the component last, it is the one selected, and Rhea will try to tessellate it. Click the base in the viewport or the outliner first.
03
Add the effect
In Effects, press Add effect and choose Tessellate.
04
Pick the component
Use the object field in the effect's controls. The dropdown lists every object in the scene; the eyedropper picks one by clicking it in the viewport.

If the Tessellate button is greyed out

No component is assigned. The effect cannot run without one, so the button stays disabled and a message says so rather than failing on press.

The controls

Every one of these is live. Drag it and the result rebuilds as you drag, and every one can be keyframed.

How many, and how big

Density0 – 4: How many copies. Each level subdivides the base once before placing, so it is four times the copies per level: 0 gives one per face, 1 gives four, 2 gives sixteen. This subdivision is internal — your base mesh is not touched.
Coverage0 – 1: What fraction of faces get a copy, chosen deterministically from the seed. At 1 every face is covered; at 0.4 the surface is sparsely populated. Lower coverage with higher density gives scattered-but-small rather than dense-and-small.
Scale0 – 20: Size of each copy relative to its face. Above 1 the copies overlap their neighbours, which is exactly what you want for shingles and scales and exactly what you do not want for panels.
Height0 – 100: How far each copy stands off the surface along the normal. The range is deliberately generous — quills and cilia need values that look absurd next to a shingle.
Taper0 – 8: How much each copy narrows towards its tip. At 1 it keeps its shape; below 1 it widens; above 1 it pinches to a point. Combined with a high Height this is what turns a blunt component into a spine, a tentacle or a hair.

How they sit

Twist±720°: Rotation about the copy's own axis, accumulating along its height. A small value gives a screw; a large one gives a helix. Applied to a fin or a blade this is the single most useful control in the section.
Tilt±360°: Lean away from the surface normal, in a consistent direction. This is what rakes louvres, angles scales into a flow, and stops a spike field looking like a pincushion.
Wobble0 – 360°: Random tilt per copy, on top of the consistent Tilt. Small amounts break up mechanical regularity; large amounts read as debris.
Scatter0 – 4: Random offset of each copy across the surface, away from its face centre. Enough scatter and the underlying face grid stops being readable, which is the difference between a pattern and a texture.
Align to normal: Whether copies stand up from the surface or keep the component's own orientation. On by default. Turn it off when you want everything pointing the same way regardless of the form underneath.

Variation

Attribute: Name of the field that drives per-copy variation. Recipes write rhea_density. Leave it blank and every copy is identical.
Variation−4 – 4: How strongly the attribute affects size. Negative inverts it, so copies shrink where the field is strong instead of growing. Zero ignores the field entirely.
Randomness0 – 12: Unstructured size variation per copy, independent of any field. This is noise, not signal — it makes a result look grown rather than manufactured.
Seed: Which random arrangement you get. Change it before changing anything else: a bad result is often just an unlucky seed, and trying five costs nothing.

Output

Keep surface: Whether the base surface stays visible underneath the copies. On by default. Turn it off for open screens and lattices where the copies are the whole object; leave it on for scales and cladding where you want a solid behind them.

Combinations worth knowing

Cilia or hair. A thin component, Height high, Taper around 3, Wobble around 20°, Scatter around 0.5. The taper is what sells it — without it you get bristles.
Raked louvres. Fin component, Tilt around 35°, Twist 0, Wobble 0, Coverage 1. Keep the randomness at zero: the appeal here is regularity.
Fish scales. Scale component, Scale slightly above 1 so they overlap, Tilt small, Height low, Keep surface on.
Barnacle encrustation. Pod component, Coverage around 0.35, Randomness high, Scatter high, Wobble around 40°.
Helical growth. Twist near its maximum with Height high and Density 0, on a Torus or Seashell base.

Live tessellation versus the Tessellate module

There are two tessellation paths in Rhea and they do different jobs.

Live (this page): Fast, adjustable, animatable, and stacks with other effects. Places copies without welding them to each other. Right for look development, motion, and anything you are still deciding about.
Tessellate module: Four mapping modes including continuous patch weaving, merged seams, strict quad output, UV and material preservation, multi-component slots, iteration. Right for a finished asset, and for anything you intend to fabricate. See Tessellate.

A reasonable workflow is to explore with the live engine until the result is right, then reproduce it in the module when you need welded, clean, game-ready or fabricable output.