variants and checks

Three questions come up on every real design. What if this dimension were different? Do these parts collide? How big is it, exactly? A pixie answers all three from the model itself, in numbers. None of them changes your design unless you say so.

You ask for these in chat. There are no buttons for variants or collision checks in the editor. The editor's own tool for a quick number is Measure.

variants

A variant is a named set of changes: new parameter values, edited steps, or edits to a model's program. A pixie can try up to 8 at once. Each is evaluated in the background, and nothing is written to the canvas, to your node, or to anyone's open tab. You get back one digest per variant: did it evaluate, what are the measurements, which steps warned.

Ask in plain words:

try the tray at 150, 162 and 175 wide and tell me which still passes the fit check

The pixie builds the variants, waits for the digests and reports. A variant that fails says why. Results are kept for seven days.

When you pick one, say so: "promote the 162 version". The pixie applies that variant's changes to the real node as a single batch, through the same path as any edit. It re-applies them to the node as it is now. If you changed the node in the meantime, the pixie sees that the batch was built on an older revision and tells you.

what it costs

Variants run on a render machine, not in your tab. Busy seconds are billed like any other machine job, to your organisation. If your organisation has no credit while billing is enforced, the batch is refused. A variant may wait up to 30 minutes in the queue and run up to 10 minutes.

collision checks

Ask: "does the board clear the case, and does anything collide when the lid opens?" The pixie runs an exact check on your placed parts, in a connected tab.

How it counts:

• Touching is contact, not a collision. A part resting on another, or a flush fit, is fine.
• Crossing is a collision. The check reports the pair and roughly how deep.
• A part wholly inside another is found too.
• Depth under 0.1 mm is ignored, which is the tolerance for curved surfaces drawn as flat triangles. The pixie can change it.
• Clearance: ask for near-misses under a distance, for example "anything closer than 0.5 mm".
• Across motion: the check can run on several poses, or sample a whole animation, up to 24 poses.

Intended fits (a screw in its insert, a button in its hole) can be named and skipped once, or stored on the model as expected contacts — up to 64 pairs — and then listed as skipped, never hidden.

Printed circuit board decals (copper, silk, pads) never collide; only the board and its parts do. Spaces are skipped, because their wall faces are not closed solids.

asking for numbers

The model answers in numbers a pixie can quote:

ask	answer
volume, mass, centre of mass	exact for solid CAD; approximate for a mesh
area of a face, length of an edge	from the face or edge you point at, or one found by direction ("the top face")
holes	a table of diameters, depths, positions and counts
distance between two parts	exact for CAD, flagged approximate for meshes
bounds of each part	min and max in millimetres
a section	the outline loops at a plane, with area and any holes
is the solid valid	yes, or what is wrong
a point inside or outside	ray test

A pixie asks up to 16 questions at a time. The answers come from the model as it stands now, and say whether that revision is still current.

To measure by hand, use Measure (hotkey <kbd>I</kbd>) and click edges, faces or holes: one edge gives a length, a circle its diameter and centre, a face its area, and two picks give the natural relation between them (a gap between parallel faces, hole centre to centre).

Packaging and spaces report their own measures with each step: sheet size, fit checks, room area and volume, capacity and sightlines. See packaging and spaces.

limits & good to know

• Variants: up to 8 per batch.
• Questions: up to 16 per request.
• Collision poses: up to 24 per check.
• Expected contacts: up to 64 pairs.
• Collision checks run in a connected tab. Number questions can also be answered by a render machine when no tab is open. Neither changes the model.
• Variants work with any parameter. A model with no parameters can still change step settings.

related

• assembly and motion
• electronics: check a board against its enclosure
• overview