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Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…ncy-labs#6748) Step 1 of the RFC. crates/develop holds the skin: panels drawn in charts of their own, bends anchored at their virtual sharps (a hem at its tangent lines), and rips. develop() lays the panels out through the bends, returns each bend's zone and what each panel loses to its setbacks, and reports a bend that closes a loop instead of forcing it. crates/doc/src/sheet_skin.rs builds the skin of a sheet body from the flat-first model and checks that developing it gives the sheet's flat. With SOLIDCRAFT_SKIN_REPORT set to a file, every sheet body that is built is checked: all 412 distinct bodies the engine's 221 sheet tests build lay out to the same flat, with no area between the two (trays, torn and slanted corners, hems, returns, folds, path flanges, flanges on a flange's side edge, converted parts). A skin with a wrong K-factor is caught. Nothing users see changes. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A panel can now lie on a cylinder or a cone: a roll, whose radius is its geometry where a bend's is a value of the joint. Each panel goes onto its neutral surface before it is laid out, so a roll flattens the way a bend of its radius would. On a cylinder, lengths round it scale by the neutral radius over the skin's: lines stay lines, and a circular arc becomes exact elliptical conics. On a cone, distances from the apex shift along the rulings: rulings and arcs about the apex stay exact, anything else is followed by chords within 0.1 um. A seam joins panels edge to edge with no zone, as where a roll meets a flat panel. A rip cuts each side by its own amount and is not followed: panels it keeps apart are laid out as pieces of their own, side by side, and a ring of seams or bends is reported until a rip opens it. Every flat segment says which segment of its panel it came from. The sheet model's 412 bodies still lay out from their skins to today's flat. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…abs#6748) A bend's zone now names its near and far edges and its ends, and a trim names the line along which it leaves the panel's material, so every edge of a development is something in the skin: a panel's own segment, a zone's edge or end, or a cut. The flat is joined from those pieces by the planar booleans, which do not yet say which input edge each output edge came from. Until they do, sheet_flat_lineage.rs recovers it after the join, from the line or arc each edge lies on, and counts the edges in tangency-labs#7990's classes. Over the 437 sheet states the engine's sheet tests build: 3722 exact, 1080 merged, 255 sources split into pieces, none found by geometry alone. The round-trip tests now fail on any edge that resolves to nothing. Every workaround for the planar booleans starts "Until the kernel's planar booleans", so they can all be found and removed together. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…itted (tangency-labs#6748) A panel now keeps its region in its own surface's parameters: a plane's coordinates, a cylinder's length along and angle round its axis, a cone's distance from its apex and angle round its axis. Flattening maps those parameters to the flat, so the surface's flow (its parameter lines) and anything drawn in its parameters carry to the flat exactly. A cone's rulings and its circles round the axis are straight lines in its parameters and flatten exactly, to lines and to arcs about the apex. A free-form panel lies on a spline surface. Its flat map is a planar spline over the surface's own breaks: linear along a straight direction, where a development is exactly linear, and cubic along a curved one, refined until the strain left is under 1e-7. It is fitted to the neutral surface's metric, I - 2hII + h^2 III, so the thickness and K-factor are in the fit rather than applied after it; a grid on the neutral surface unfolded triangle by triangle is the starting guess. A straight line of the parameters flattens to exact Bezier pieces, one per knot span; a stretch the fit cannot avoid is reported with the flat, never forced. A quarter cylinder written as a rational spline flattens to within 4e-9 mm of its neutral arc (strain 9e-8); a strip bent along a cubic to within 5e-10 mm of its neutral curve's length (strain 1.7e-8); a saddle reports 1.8% stretch. The sheet model's 437 states still lay out to the same flat as today's. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
tangency-labs#6748) Convert to Sheet Metal can now go through the skin: sheet.convert with skin: true makes a new feature, sheet_skin_convert. No face is fixed. Every face of a solid, or of one side of a shell or a plate, becomes a panel of the sheet, less the faces the user skips. A cylinder or a cone is a roll that keeps its modeled radius, joined by seams where the sheet runs on smoothly. Every sharp edge between two faces of the sheet is cut open, as today's Convert cuts it, until the user picks it as a bend. A ring of bends is refused, naming its edges. A solid's material lies inside its faces, or outside them with direction: outside; a shell or a plate keeps its own thickness. The body stays as modeled, and the model keeps the converted body's flat pattern (saved in the model cache as skins), which sheet.flat_pattern shows. The flat is drawn in the plane of the sheet's largest face. The Convert dialog has a Through the skin switch: with it on, the inputs are the body, the bend edges and the faces to skip, with the material's side. Edit Feature brings them all back. Tested against today's Convert: a channel with modeled corners converts with no picks to the flat today's Convert makes from those corners as bends, a shelled tray and a solid block with their floor edges picked match it too, and a square tube opens where a corner is left unpicked. The same block with its material outside is a tray T bigger all round, and its flat is 4T longer each way. A block the size of the tray's cavity, with its material outside, is the same metal as the tray; its flat matches but at the corners, where its bend zones run the length of the drawn edge rather than of the metal. That is fixed next. Changes a default: no. The switch is off by default and today's Convert is unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…gency-labs#6748) Converted through the skin, a bend's zone used to run the whole length of its drawn edge. Where a rip cuts the panels at a corner, that edge is the outside corner of the sheet when it is drawn from outside and the inside corner when it is drawn from inside with its material out, so one piece of metal unfolded two ways at its corners. Now a bend is cut square at the rip's own plane, the one halfway between the two ripped panels that already cuts their ends, so that none of its metal comes nearer than half the gap to it. At a 90 degree corner that is R + T + gap / sqrt 2 from the end of the edge drawn outside, and R + gap / sqrt 2 from the end of the edge drawn inside: the same place. Past a cut end the panels on either side stop at their tangent lines, the corner's relief, whatever their tail: a bend's zone ends can now be marked relieved, start and end apart. A base running on past a shorter flange's free end still keeps its edge. A tray shelled from a 100 x 60 x 30 box, the solid box itself, and a box the size of the tray's cavity converted with its material outside now unfold to the same flat, corners included, to 1e-6 mm2. The same box with its material outside is a different tray, T bigger all round, and its flat stays 4T longer each way. The corners differ from today's Convert, whose bend zones run on into the corner past the walls; the outlines' extents are unchanged. Changes a default: no. Only Convert through the skin, which is new, is affected. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…corners and all (tangency-labs#6748) Converted through the skin, a body used to stay the solid as modeled while the model kept its flat pattern: a block stayed a block. Now the body becomes the sheet metal part, sewn from the same pieces the flat pattern is joined from, so the two can't disagree. solidcraft-develop gains fold(), the other half of develop(). Each piece of the flat goes where the caller says its first panel lies, and every other panel where its bends and seams put it; a rip holds nothing. A bend's metal is the ring sector between its inside and outside radii, its flat zone wrapped onto it by the neutral arc. Any point of the flat, at any depth through the sheet, then has its place in space: on a plane, a roll (a cylinder or a cone, undone from its flat chart) or a bend. Rigid3 joins Rigid2. The solid is each piece's two faces, one on the skin and one a thickness into the material, and a wall along each edge no other piece shares. An edge folds to a line or an arc where it runs along or across a bend or a roll, and to a chain of cubic pieces within 1e-7 mm elsewhere. Convert places each piece by its first face, and checks that every other face folds back onto itself: a joint read wrong is an error, never a sheet in the wrong place. No sheet comes first. Every panel is a sheet meeting the others at bends and rips, and nothing about the result depends on which way a joint runs or which panel is larger. Reliefs are values of the skin, never drawn on a panel, so they move with the bends' radius and the sheet's thickness: - A bend's end can be notched (both panels stop at their tangent lines past it), slotted (the rule's bend relief, in whichever panel runs on past it), or torn tight against a plane: its metal kept off the plane by as much as at its two ends and, between, in proportion to its turn, so that a torn corner closes on the rip's plane all the way round the bend. The torn end is drawn in the flat as a cubic spline in the fewest even spans within a micron of that curve (a couple, on a tray), and folds to one smooth wall: the fold takes a run of free-form edges that join with no corner as one edge. A lap or a free-form rip will part the panels along other surfaces. - A corner relief belongs to the corner, the two bends meeting there, not to any sheet round it: a round or a four-sided relief centered where the bends' zones' center lines cross, cut from every piece of the flat it reaches. Convert reads the rule's corner relief, its size and its bend relief. Two bends standing on one panel and meeting at a corner of it end where their tangent lines on it cross, notched, with the corner's relief, or torn tight against the plane of the rip between their other panels. A bend that a rip cuts beside ends where its metal reaches the rip's plane; a wall standing on part of another panel's edge bends only where it stands. A relief that doesn't fit is left out with a note. This replaces the gap/sqrt 2 the last commit cut off each bend at a corner: two notched bends meet along a line and pucker into the open corner. The sheet's side of a plate now takes a wall whose outside runs on in one plane with the plate's edge, and never a face whose face behind is the sheet's. Checked, solid against solid: a shelled tray, a block drawn from outside and the tray's cavity drawn from inside with its material out fold to one solid and one flat for every corner relief; notched, that is today's Convert of the shelled tray within 1e-9 of its volume, and the block with its material outside today's Convert of a tray T bigger all round. A tray whose walls outsize its floor gets the same four corner reliefs as a shallow one. A torn edge, folded, keeps its metal off the rip's plane by its share of the gap within a micron, through the whole thickness. An icosahedron bent along a spanning tree of its faces bends its triangles' whole edges, gets a round relief at each of the ten corners where two bends meet on a face, and folds. A plate with a wall on part of an edge folds to today's, bend relief included. A square tube with three corners bent, and a channel whose modeled rolls today's Convert bends, fold to today's solids within 2e-12. Changes a default: no. Only Convert through the skin, which is new, is affected. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…at they are, no primary face (tangency-labs#6748) WORK IN PROGRESS. This is a checkpoint, not a finished feature: - The legacy infrastructure is not ripped out yet: the fixed-face Convert and the "skin" switch are still in place, and saved documents are not upgraded. - Convert still reads the body's display tessellation for its faces' outlines, the edges between them, the sheet's thickness and the faces' areas. Rips along curved edges off a plane follow its facets. Every such place is marked "Until the kernel ... (tangency-labs#1597)". - Landing the whole feature needs the kernel swap (tangency-labs#1597): exact B-rep topology and curves for every face, faces whole across a revolve, edges whole round any sweep. It also needs the topological naming stability work, so that sheet features can hold on to the flat's edges. What is in: - Rips are one operation. A rip carries its edge on each panel (as points, and exactly where the body knows it), the sheet's turn along it, and a lap. The cut at each point comes from the lap for the turn there, measured square to the edge with the panel's own surface metric, so a rip between two planes, round a roll's rim or between free-form panels is the same computation. - Each panel's flat outline is built directly: every ripped stretch is replaced by its cut, and each cut is joined to the edge beside it where they cross, by carrying them on to where they meet (within a miter limit), or by a square step. Nothing is cut away by overlapping strips, so no edge is left in pieces, and every edge of the flat says what it is: the panel's own edge or a given rip's cut (EdgeFrom). The flat lineage reads that instead of guessing. - Edges the kernel knows exactly in a plane (lines, arcs) are cut back exactly: a half round's rim stays one arc. - A half-turn roll was laid a whole turn away from its seam (an angle read as 2 pi instead of 0): angles are now unwrapped from the middle of the panel's span. This was the mangled tombstone. - There is no primary face: the walk starts on the largest face of any shape, a shell's thickness is measured between the exact surfaces, and each piece roots on its largest face. A cylinder or cone with no flat face converts. A ring of smooth seams (a tube) opens at the seam the walk did not cross; a ring of bends is still the user's to open. - The folded solid splits an arc only past three quarters of a turn, as the kernel's profiles do. Tests: a tombstone drawn from outside and from inside agrees and keeps its rims whole; a half pipe and a whole pipe drawn as surfaces roll out to their exact widths; rip, join and exact-arc tests in develop. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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This work continues on |
h0witzer
changed the title
This was referenced Nov 1, 2026
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Thanks for this! I'm closing older PRs that have gone quiet or drifted from main, since a lot has changed in the last couple of weeks. If you'd still like this in, please open a fresh PR against current main; happy to review it. |
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Change
Part of #6748: this is step 1, so merging it does not close the RFC.
Step 1 adds a development module that develops a surface of panels and joints into a flat region with exact curves:
It goes in new files only. Nothing users see changes.
Changes a default: no
Validation
To come:
Integration status
The claim commit is on upstream
mainat 545232b.🤖 Generated with Claude Code