VectorPaint compass states: share a hinge and preserve needle/pencil identities

English translation of the Chinese original, translated on 2026-11-12. Original publication dates, attribution, code and version notes are retained.

Compass legs resemble an inverted V, but changing their spread must not move the hinge or swap needle and pencil. Use two invented static views to check component identity and direction. This uses no automatic compass tool and gives no manufacturing or repair instructions; a drawn arc is not evidence of simulated physical motion.

Define the shared frontal view

Use an 1800×1200 landscape canvas with a wider left state and narrower right state. Keep the needle leg on each drawing’s left and pencil leg on its right; do not mirror the second view. Staedtler’s compass information identifies the instrument category, while lengths, hinge appearance and colours are invented here rather than universal. Label static opening states, without precise radius readings, angle readings or instrument grades. Do not invent branding.

Place hinge before the leg axes

Start each view with one hinge centre and two pale axes descending from it. Equal simplified leg lengths aid comparison: change directions rather than secretly shortening a leg to obtain a preferred tip separation. Each drawing has one shared connection; their side-by-side placement translates the whole instrument, so their absolute canvas coordinates differ. Group needle leg, pencil leg and head separately. If rotation is visual, reposition against references and state its approximate nature. Assume no hidden pivot command or mechanical-constraint feature.

Keep the needle tip on its leg axis

Build a narrow body along the left axis, tapering to a needle tip near its extension. Connect the proximal end to the head rather than floating a thin needle beside it. Preserve detail in the enlarged drawing; a small delivery icon may exaggerate thickness for visibility without claiming a real diameter. For a doubled tip, inspect overlapping strokes and highlights rather than adding points for technical appearance. No piercing, pressing or calibration is performed: sharp parts exist only in the illustration, identifying components without asserting safety.

Give holder and lead distinct segments

At the right leg’s end, draw a wider holder followed by a thinner lead or drawing tip; the whole leg is not black lead. Align it with the leg axis, with its root appropriately occluded by the holder rather than piercing a sidewall. Keep the same simplified end structure in both states, including the narrower one. Omitting screws is acceptable; drawn screws are surface hints, not invented adjustment mechanisms. Both tips remain below the hinge, with background separating the legs rather than a shadow filling the V into a solid triangle.

Copy identities before changing spread

Change directions in a copy of the complete first view, retaining whole leg groups and checking needle-left/pencil-right. Keep the head’s frontal position while returning proximal ends to its hinge region; arbitrary rotations about separate bounding boxes may leave gaps. If a common pivot cannot be guaranteed, retain hinge and axes as references, then align each rotated leg’s proximal end to the centre and distal end to its target axis. It remains a diagram. Tips need not stay at one place across the two views: this compares opening structure, not the full action of drawing around a fixed needle. Temporarily label needle/pencil legs A/B in the first view and retain those labels in the narrower view. A remains needle and B pencil; metal colour alone may conceal swapped ends.

Do not turn tip separation into a measured radius

A pale line between tips can indicate wider versus narrower opening, but its illustrated length is not a millimetre radius. Actual use involves contact, posture, lead and paper conditions not measured here. Equal simplified legs suggest approximate visual symmetry, not a guarantee about real instruments. A whole circle through the hinge proves no opening accuracy. Any imagined circular track belongs to a labelled checking copy, not an automatic result. Compare tip separation only; derive no precision, stability or durability rating.

Use a swapped-identity copy for troubleshooting

In a separate narrower-state copy, deliberately put a needle on the right and pencil on the left and label the identity swap. It may still resemble a compass, but correspondence with the first view fails. Restore the ends or whole leg identities rather than merely relabelling. For a drifting head, return to the shared hinge reference; for legs emerging from unrelated head edges, inspect their proximal joins. Keep the erroneous copy separate from delivery layers. Hide shadows and highlights first so bright lines do not create a third leg or false tip.

Accept three components and two tips in both states

Save the original and open the export. In each state, identify head, needle leg and pencil leg, then check distinct tips and connected background gaps. At intended size, repair a lost lead locally rather than thickening both legs. Retain the viewing convention; hide ordinary drawn axes before delivery and check native reference displays against actual exports. Keep two valid states, the swapped example and shared-hinge explanation. No physical compass was used or roundness measured. Two coherent states demonstrate neither kinematic simulation nor automatic component constraints.