VectorPaint hinged boxes in three poses: keep the hinge fixed as the lid changes direction

English translation of the Chinese original, translated on 2026-11-07. Original publication dates, attribution, code and version notes are retained.

Three hinged-box states should share a body and hinge, not three roughly similar boxes. Build simplified side views of closed, diagonal and upright lids, checking their origin and length manually. This calculates no hinges, collision or bending and establishes no physical packaging load safety.

Fix the body and one rear hinge

Create a 1200 by 800 pixel canvas and one source state. The body side rectangle runs (300,500) to (700,700), with upper-left hinge A. Left means rear and right front in this side view. The closed lid runs horizontally from A to the upper right, length 400 pixels. Identify body/lid/pivot; coordinates are illustrative, not physical packaging dimensions. Save the complete source and preserve body position/display size across copied states instead of shrinking a box to fit a lid.

Separate lid and rim in the closed state

Closed lid/rim may coincide; temporary colour or an explicitly explanatory offset can distinguish ownership without inventing two materials. Keep A clear and the front end at the body’s upper-front corner. Any thickness is simplified, not calculated folds/seals. Hide the lid to inspect a complete body source, then restore instead of deleting rim sources to conceal gaps. If labelled, decide whether text moves with the lid or remains an external annotation, consistently across poses.

Keep A and lid length in the diagonal pose

Copy without moving the body and put the lid end upper-right of A, retaining its root. For rotation, verify the actual pivot rather than assuming the selection-box centre. Otherwise locate the end on a radius-400 circle around A and redraw the lid. Label this manual pose without unverified angular precision. Do not shorten a diagonal lid for appearance; its drawing length stays equal to the closed state. Keep the circle as a draft reference, not a physical box part.

Return to the same pivot for the upright state

The upright lid runs A→(300,100), still length 400 with unchanged body. Compare pivots/labels before direction; an upright line does not establish a real hinge assembly. These independent images provide no animation or physical angle stops. If arranged in a row, translate each complete state into its frame without internal rescaling and relabel its A. Aligning lid tips alone destroys body/pivot comparability.

Establish stacking and cavity before shading

Start with an unfilled body wireframe and solid lid, identifying any cavity as explanatory. A filled body needs explicit rear occlusion, not claims that covered sources were deleted. Hide highlights to inspect body/lid/A in all poses. Repair the lid-root endpoints; do not conceal connection gaps beneath a large black pivot circle. No latch, spring or insert is included; additions need their own attachments/stacking. A lid line implies none of those mechanisms. Colour distinguishes poses without replacing geometric consistency.

Update all lid sources after changing body length

Extend the body front by 100 in a copy. If the lid must still cover the opening, length changes 400→500. Update closed first, then diagonal/upright through a new-radius reference with pivot fixed. Do not leave the other poses at 400 under the same-box claim. Retaining an old lid is a different explicitly stated design, no longer full coverage. Name tests and compare at one scale; copies do not update related states automatically. This tests diagram maintenance, not physical packaging feasibility.

Retain three states and the nonsimulation scope in output

Save body, length references and all poses. Inspect pivots, ends and labels in exports. For crowded small strokes, add a separate explanatory detail rather than changing relationships. Test backgrounds; white fill is not an automatic cavity. Name hinged side-view states, revision and size and exclude a 500-length test from the 400 set. Explain independent poses for editable recipients. Physical production needs materials/joints/dimensions; this provides no collision or safety validation.

Check pivot and selection for a drifting lid root

A drifting A needs pivot/reference-circle checks, not moving the body to chase it. Measure upright length A-to-end rather than whole-image height. Different bodies suggest scaling/selection, not a title problem. A short closed lid needs body-length/coverage review, not a thick extension patch. Recheck fixed body, common pivot, lid length and pose labels to compare one object’s poses instead of three merely similar boxes.