37 R11: knife polylines, live symmetry, Smart unwrap core half (1.28)

CLAUDE.md

@@ -845,6 +845,19 @@ loadable play content. Everything a user does must be visible to connected peers
   0 welded edges used other than twice AND 0 directed edges walked twice the same way.
   CSG output (three-bvh-csg, `meshBooleanCore`) is full of T-junctions — closed to the
   eye, cracked to every welded-key tool — so `repairTJunctions` runs on every result.
+  37 R11 (1.28): the KNIFE is a polyline (`knifeCutCore`, pure): every corner on the mesh is
+  INSERTED as a vertex first (per welded edge when it sits on one), then each segment is a
+  straight cut on the previous result — a cut ending at an inserted vertex leaves through ONE
+  crossing and the one-crossing fan lands on that vertex, so no per-triangle cut graph is
+  needed. LIVE SYMMETRY (`meshToolParams.liveSymmetry`, local, not persisted) hooks the
+  OPERATOR boundary, never applyGeometrySnapshot/applyMeshGeo (restore paths): one-shot ops
+  record through `recordOp` (mirror on a microtask, after the op's own selection code, then
+  `entry.after` is rewritten — ONE undo entry), the adjust engine mirrors the pure result
+  (`mirrorAdjustResult`, side fixed per adjust), vertex-mode ops pass `op=true` to
+  commitMeshGeoTriple/Snapshot, and a vertex DRAG moves each vertex's mirror twin live
+  (meshEdit `liveTwins`; plane vertices are pinned to the plane). The source side is the side
+  the edit CHANGED (`editSide`), `symKeep` only breaks a tie. `mirrorTrisCore` is the shared
+  pure half of Symmetrize.
   Two traps live here. The LIVE PREVIEW (`liveGeometryUpdate`) swaps geometry every
   frame, so topology has to survive the preview or there is nothing left for the
   commit to carry — that was the real reason a rotated band still lost its quads after

src/components/Scene.svelte

@@ -56,11 +56,8 @@
 	import { startSnapEngine, setSnapPointer, beginSnapDrag, endSnapDrag, maybeSnapGizmo, snapAnchorPicking, snapAnchorClick, updateSnapAnchor } from '$lib/snapEngine';
 	import { meshPivotPicking, meshPivotClick, tickMeshPivotMarker } from '$lib/meshPivot';
 	import { editingObject, enterEditMode, exitEditMode, raycastHandles, clearVertexSelection, onProxyMoved, onProxyDragChanged, tickMeshEdit, selectVerticesInRect } from '$lib/meshEdit';
-	import { faceEditObject, enterFaceEdit, faceEditOp, commitArmedFaceOp, exitFaceEdit, highlightFaceByTriangle, attachFaceGizmo, detachFaceGizmo, onFaceGizmoMoved, onFaceGizmoDragChanged, autoApplyFaceOp, faceEditMulti, toggleFaceSelection, clearFaceSelection, pickFaceUnit, lookupEditable, faceEditSubmode, faceEditSelectedTris, setFaceSubmode, selectElementsInRect, pickEdge, pickEdgeAt, clearEdgeSelection, knifeCut, setFaceOp, knifePreview, cancelKnife, tickEditWireframe } from '$lib/faceEdit';
+	import { faceEditObject, enterFaceEdit, faceEditOp, commitArmedFaceOp, exitFaceEdit, highlightFaceByTriangle, attachFaceGizmo, detachFaceGizmo, onFaceGizmoMoved, onFaceGizmoDragChanged, autoApplyFaceOp, faceEditMulti, toggleFaceSelection, clearFaceSelection, pickFaceUnit, lookupEditable, faceEditSubmode, faceEditSelectedTris, setFaceSubmode, selectElementsInRect, pickEdge, pickEdgeAt, clearEdgeSelection, knifeClick, knifeHover, knifePreview, tickEditWireframe } from '$lib/faceEdit';
 	import { fireObjectClick } from '$lib/flowRuntime';
-	// M9b: the first click of a knife cut, in CSS pixels. This component is lang="ts", so
-	// the annotation is TS syntax — a JSDoc @type cast is ignored here (the documented trap).
-	let knifeFrom: number[] | null = null;
 	import { peerScenes } from '$lib/peerScenes';
 	import { initVRControls, updateVRControls, raycastMenu, radialStickSelection, raycastPanel, raycastPalette, raycastProps, raycastPrefabs, raycastKeyboard, raycastChat, raycastEdit, raycastSnap, raycastSettings, raycastApprove, placePrefabGhost, vrFaceTrigger, vrVertexTrigger, vrVertexGrabStart, vrVertexGrabEnd, beginStretchSliderDrag, endStretchSliderDrag, executeVRMenuAction, resetWorldRig, onInputSourcesChange, worldToContentPose, boxSelectStart, boxSelectEnd, boxSelectActive, applyVRFrameRate, shouldSendHands, onHandPinchStart, onHandPinchEnd, pinchMenuToggledAt, firePingIfArmed, vrModuleTriggerStart, vrModuleTriggerEnd, vrModuleSelectSwallowed, handSnapshot, vrGrabbedUuids, hapticKnock, hapticPulse, onVRSessionStart } from '$lib/vrControls';
 	// 30b (vr-play): the game in your hands — hover/press haptics (P1), the sweep (P4)
@@ -918,8 +915,8 @@
 			// 19-B: the element-snap search is cursor-based — track the pointer while a
 			// gizmo drag runs (this listener is on window, so mid-gesture moves arrive)
 			if ($TControls?.dragging) setSnapPointer(event.clientX, event.clientY);
-			// M9b: the knife's rubber band follows the pointer between the two clicks
-			if (knifeFrom) $knifePreview = { from: knifeFrom, to: [event.clientX, event.clientY] };
+			// M9b: the knife's rubber band follows the pointer while a cut is pending
+			if ($knifePreview) knifeHover([event.clientX, event.clientY]);
 			if (marqueeStart) {
 				$marqueeRect = {
 					x0: Math.min(marqueeStart[0], event.clientX),
@@ -1140,21 +1137,12 @@
 			// face edit mode (135 desktop): a click highlights the face under it,
 			// and 163 attaches the transform gizmo to it (drag = move/rotate/scale)
 			if ($faceEditObject) {
-				// M9b KNIFE: two clicks, anywhere — the cut is a SCREEN line, so it does not need
-				// to hit the mesh at all (that is the point: you cut across a silhouette). The
-				// first click only records; the second cuts and disarms.
+				// M9b KNIFE: clicks anywhere — the cut is a SCREEN line, so it does not need to hit
+				// the mesh at all (that is the point: you cut across a silhouette). The first click
+				// only records; 37 R11: an ADDITIVE click (the selection's add gesture) places a
+				// polyline corner, a plain one ends the cut, cuts and disarms.
 				if ($faceEditOp === 'knife') {
-					if (!knifeFrom) {
-						knifeFrom = [event.clientX, event.clientY];
-						$knifePreview = { from: knifeFrom, to: [event.clientX, event.clientY] };
-						showToast('Knife: click the far end of the cut (Esc cancels)');
-					} else {
-						const from = knifeFrom;
-						knifeFrom = null;
-						cancelKnife();
-						knifeCut(from, [event.clientX, event.clientY]);
-						setFaceOp('move'); // a one-shot tool: back to the default after a cut
-					}
+					knifeClick([event.clientX, event.clientY], event.ctrlKey || event.shiftKey || event.metaKey || $multiSelectMode);
 					return;
 				}
 				// A8: lookupEditable also finds the scene-root collider-edit proxy

src/components/editors/UvEditor.svelte

@@ -1293,7 +1293,7 @@
 			tooltip: pickedTris
 				? 'Applies to the ' + pickedTris + ' face triangles selected in Edit Mesh'
 				: 'Applies to the whole mesh',
-			children: backends.map((backend) => ({
+			children: unwrapBackends().map((backend) => ({
 				label: backend.label,
 				action: () => runUnwrap(backend.key)
 			}))
@@ -1431,7 +1431,9 @@
 	}
 
 	let unwrapOpen = $state(false);
-	const backends = unwrapBackends();
+	// re-read whenever a menu opens: a module (37 R11's Smart unwrap) can register a backend
+	// while this editor is already mounted, and a list read once at mount never showed it
+	let backends = $state(unwrapBackends());
 
 	/** @param {string} key */
 	async function runUnwrap(key) {
@@ -1732,7 +1734,10 @@
 							? 'Generate new UVs for this mesh, or just the faces selected in Edit Mesh'
 							: editable.reason}
 						disabled={!editable.ok}
-						onclick={() => (unwrapOpen = !unwrapOpen)}
+						onclick={() => {
+							if (!unwrapOpen) backends = unwrapBackends();
+							unwrapOpen = !unwrapOpen;
+						}}
 					>Unwrap ▾</button>
 					{#if unwrapOpen}
 						<div id="uv-unwrap-menu" class="absolute left-0 top-full z-30 mt-1 w-44 rounded-sm border border-gray-600 bg-gray-800 py-1 shadow-lg">

src/components/menu/KnifeOverlay.svelte

@@ -12,6 +12,16 @@
 
 {#if $knifePreview}
 	<svg class="knife-overlay" width="100%" height="100%" aria-hidden="true">
+		<!-- 37 R11: the corners placed so far (a polyline cut), then the live segment -->
+		{#if $knifePreview.points.length > 1}
+			<polyline
+				class="knife-placed"
+				points={$knifePreview.points.map((p) => p[0] + ',' + p[1]).join(' ')}
+				fill="none"
+				stroke="#ff7a1a"
+				stroke-width="1.5"
+			/>
+		{/if}
 		<line
 			x1={$knifePreview.from[0]}
 			y1={$knifePreview.from[1]}
@@ -21,7 +31,9 @@
 			stroke-width="1.5"
 			stroke-dasharray="6 4"
 		/>
-		<circle cx={$knifePreview.from[0]} cy={$knifePreview.from[1]} r="3.5" fill="#ff7a1a" />
+		{#each $knifePreview.points as point, i (i)}
+			<circle cx={point[0]} cy={point[1]} r="3.5" fill="#ff7a1a" />
+		{/each}
 		<circle
 			cx={$knifePreview.to[0]}
 			cy={$knifePreview.to[1]}

src/components/menu/MeshEditPopup.svelte

@@ -37,6 +37,7 @@
 		mergeDistance,
 		symAxis,
 		symKeep,
+		liveSymmetry,
 		optionsFocus,
 		focusTool,
 		hasOptions,
@@ -238,7 +239,7 @@
 		{ op: 'move', label: 'Move', hint: 'G', oneShot: false, param: false, icon: 'move', desc: 'seat the gizmo on the selection and drag it' },
 		{ op: 'extrude', label: 'Extrude', hint: 'E', oneShot: false, param: false, icon: 'extrude', desc: 'pull the face out along its normal' },
 		{ op: 'inset', label: 'Inset', hint: 'I', oneShot: false, param: false, icon: 'inset', desc: 'shrink a copy inside a stitched ring' },
-		{ op: 'knife', label: 'Knife', hint: 'K', oneShot: false, param: false, icon: 'knife', desc: 'cut across the mesh: click one end of the line, then the other' }
+		{ op: 'knife', label: 'Knife', hint: 'K', oneShot: false, param: false, icon: 'knife', desc: 'cut across the mesh: click one end of the line, then the other (Shift+click adds corners)' }
 	];
 	const ACTION_OPS = [
 		{ op: 'bevel', label: 'Bevel', hint: '', oneShot: true, param: true, icon: 'bevel', desc: "chamfer the selected face's border" },
@@ -1447,6 +1448,28 @@
 						})}>Symmetrize</button
 				>
 			</div>
+			<!-- 37 R11: LIVE symmetry — every edit mirrored, vertex drags move their twin -->
+			<label
+				class="tbx-row flex items-center gap-1 text-xs text-gray-300"
+				title="While on, every edit is mirrored across the axis above, from the side you edited — and dragging a vertex moves its mirror twin with it. Symmetrize first if the mesh is not symmetric yet."
+			>
+				<input
+					id="mesh-sym-live"
+					class="tbx-check"
+					type="checkbox"
+					checked={$liveSymmetry}
+					onchange={(e) => {
+						liveSymmetry.set(e.currentTarget.checked);
+						if (e.currentTarget.checked)
+							showToast(
+								'Live symmetry on: edits are mirrored across ' +
+									$symAxis.toUpperCase() +
+									'. Symmetrize first if the mesh is not symmetric yet.'
+							);
+					}}
+				/>
+				live symmetry
+			</label>
 		</ToolboxSection>
 
 		<ToolboxSection key="display" label="Display" open={true} id="mesh-sec-display">

src/components/menu/MeshToolOptions.svelte

@@ -22,7 +22,10 @@
 	import {
 		faceEditAmount,
 		faceAutoApply,
-		opAdjustState
+		opAdjustState,
+		knifePreview,
+		knifeFinish,
+		knifeDropCorner
 	} from '$lib/faceEdit';
 	import { proportionalRadius } from '$lib/meshEdit';
 	// 19-A P4: scrubbing the radius previews the falloff RING at the current
@@ -693,6 +696,26 @@
 {:else if focus === 'knife'}
 	<span class="tbx-label">Knife options</span>
 	<div class="tbx-row text-xs text-gray-400">
-		Click one end of the cut, then the other. Esc drops a pending cut.
+		Click one end of the cut, then the other. Shift+click places a corner and keeps going
+		(a polyline); Enter ends at the last corner, Backspace takes one back, Esc drops the cut.
 	</div>
+	<!-- 37 R11: touch has no Enter/Backspace — the same two actions as buttons -->
+	{#if $knifePreview}
+		<div id="knife-pending" class="tbx-row text-xs text-gray-300">
+			<span>{$knifePreview.points.length} {$knifePreview.points.length === 1 ? 'point' : 'points'}</span>
+			<button
+				id="knife-undo-corner"
+				class="tbx-cmd"
+				title="Take the last point back (Backspace)"
+				onclick={() => knifeDropCorner()}>Back</button
+			>
+			<button
+				id="knife-finish"
+				class="tbx-primary"
+				disabled={$knifePreview.points.length < 2}
+				title="Cut through the points placed so far (Enter)"
+				onclick={() => knifeFinish()}>Cut</button
+			>
+		</div>
+	{/if}
 {/if}