Cache measurement snap candidates

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Stability: make the direct-view load gate settings-aware for preferred OBJ conversion and keep mobile direct-format reads on Obsidian vault APIs instead of desktop Node path helpers.
 - UI: upgrade measurement calibration so users can scale the loaded model uniformly from the latest ruler distance, keep overlays anchored in model space, apply locked model-size scaling from one known axis, and verify the workflow through preview automation.
 - UI: make distance measurement lock the selected object by default and snap endpoints to mesh vertices or visible crease/perimeter triangle edges, filtering coplanar face diagonals and preferring edge projection outside the corner radius, with first-click target selection when needed and Alt/Option-click preserving the older free surface pick as a backup.
+- Performance: cache selected-target measurement snap candidates while measuring so hover previews do not repeatedly rebuild vertex and edge lists for the same object.
 - UI: restyle distance measurements as orthographic drawing-style dimension callouts with extension lines, arrowheads, and compact drafting labels instead of thick freehand ruler lines.
 - UI: remove the preview canvas native hover tooltip while preserving keyboard shortcut metadata for accessibility.
 - UI: clarify render scale versus measurement scale by showing render resolution as percentages, syncing the toolbar to the active renderer budget, and applying the configured scale to `3dgrid`.

src/render/babylon/scene.ts

@@ -116,6 +116,7 @@ import {
   setMeasurementCanvasActive,
   snapMeasurementPointToGeometry,
   unscaleMeasurementPointToBase,
+  type MeasurementGeometrySnapInput,
   type MeasurementSnapEdgeCandidate,
   type MeasurementSnapVertexCandidate,
   type MeasurementReading,
@@ -312,6 +313,8 @@ export class BabylonModelPreview implements WorkbenchPreview {
   private measurementMarkerPoints: Vector3[] = [];
   private measurementTargetNode: BabylonSelectablePartNode | null = null;
   private measurementTargetMeshes: AbstractMesh[] = [];
+  private measurementSnapInputCache: MeasurementGeometrySnapInput | null = null;
+  private measurementSnapInputCacheTargetId: number | null = null;
   private measurementSnapKind: MeasurementSnapKind | null = null;
   private readonly measurementObservers = new Set<() => void>();
   private pendingPoint: Vector3 | null = null;
@@ -1079,6 +1082,7 @@ export class BabylonModelPreview implements WorkbenchPreview {
 
   setMeasurementScale(scale: MeasurementScale): void {
     this.measurementScale = sanitizeMeasurementScale(scale);
+    this.invalidateMeasurementSnapInputCache();
     this.applyMeasurementModelScale();
     this.updateMeasurementOverlayPositions();
     this.updateMeasurementLabels();
@@ -1167,6 +1171,7 @@ export class BabylonModelPreview implements WorkbenchPreview {
     this.measurementBaseRootScaling = new Vector3(1, 1, 1);
     this.measurementBaseBounds = null;
     this.measurementMarkerPoints = [];
+    this.invalidateMeasurementSnapInputCache();
   }
 
   private applyMeasurementModelScale(): void {
@@ -1878,6 +1883,7 @@ export class BabylonModelPreview implements WorkbenchPreview {
 
   private setMeasurementTargetNode(node: BabylonSelectablePartNode | null, notify = true): void {
     this.clearMeasurementTargetVisual(false);
+    this.invalidateMeasurementSnapInputCache();
     const target = node && !isBabylonNodeDisposed(node) ? this.findSelectableNode(node) : null;
     if (!target || isBabylonNodeDisposed(target)) {
       this.measurementTargetNode = null;
@@ -1940,6 +1946,11 @@ export class BabylonModelPreview implements WorkbenchPreview {
     }
   }
 
+  private invalidateMeasurementSnapInputCache(): void {
+    this.measurementSnapInputCache = null;
+    this.measurementSnapInputCacheTargetId = null;
+  }
+
   private getMeasurementTargetName(): string | null {
     const target = this.measurementTargetNode;
     if (!target || isBabylonNodeDisposed(target)) return null;
@@ -1977,14 +1988,12 @@ export class BabylonModelPreview implements WorkbenchPreview {
     return toBabylonVector3(snapped.point);
   }
 
-  private createMeasurementGeometrySnapInput(): {
-    vertices: MeasurementSnapVertexCandidate[];
-    edges: MeasurementSnapEdgeCandidate[];
-    targetId?: string;
-    vertexRadius: number;
-  } | null {
+  private createMeasurementGeometrySnapInput(): MeasurementGeometrySnapInput | null {
     const target = this.measurementTargetNode;
     if (!this.rootMesh || !target || isBabylonNodeDisposed(target)) return null;
+    if (this.measurementSnapInputCache && this.measurementSnapInputCacheTargetId === target.uniqueId) {
+      return this.measurementSnapInputCache;
+    }
     const meshes = this.getMeasurementTargetMeshes(target);
     if (meshes.length === 0) return null;
 
@@ -2013,12 +2022,15 @@ export class BabylonModelPreview implements WorkbenchPreview {
     if (vertices.length === 0 && edges.length === 0) return null;
     const bounds = this.getMeasurementTargetBounds();
     const size = bounds ? getPreviewBoundsSize(bounds) : { x: 1, y: 1, z: 1 };
-    return {
+    const input = {
       vertices,
       edges,
       targetId,
       vertexRadius: Math.max(size.x, size.y, size.z, 0.001) * 0.045,
     };
+    this.measurementSnapInputCache = input;
+    this.measurementSnapInputCacheTargetId = target.uniqueId;
+    return input;
   }
 
   private getMeasurementTargetMeshes(target = this.measurementTargetNode): AbstractMesh[] {

src/render/three/scene.ts

@@ -112,6 +112,7 @@ import {
   setMeasurementCanvasActive,
   snapMeasurementPointToGeometry,
   unscaleMeasurementPointToBase,
+  type MeasurementGeometrySnapInput,
   type MeasurementSnapEdgeCandidate,
   type MeasurementSnapVertexCandidate,
   type MeasurementReading,
@@ -299,6 +300,8 @@ export class ThreeModelPreview implements WorkbenchPreview {
   private measurementMarkerPoints: Vector3[] = [];
   private measurementTargetObject: Object3D | null = null;
   private measurementTargetHelper: BoxHelper | null = null;
+  private measurementSnapInputCache: MeasurementGeometrySnapInput | null = null;
+  private measurementSnapInputCacheTarget: Object3D | null = null;
   private measurementSnapKind: MeasurementSnapKind | null = null;
   private readonly measurementObservers = new Set<() => void>();
   private pendingPoint: Vector3 | null = null;
@@ -938,6 +941,7 @@ export class ThreeModelPreview implements WorkbenchPreview {
 
   setMeasurementScale(scale: MeasurementScale): void {
     this.measurementScale = sanitizeMeasurementScale(scale);
+    this.invalidateMeasurementSnapInputCache();
     this.applyMeasurementModelScale();
     this.updateMeasurementOverlayPositions();
     this.updateMeasurementLabels();
@@ -1026,6 +1030,7 @@ export class ThreeModelPreview implements WorkbenchPreview {
     this.measurementBaseRootScale.set(1, 1, 1);
     this.measurementBaseBounds = null;
     this.measurementMarkerPoints = [];
+    this.invalidateMeasurementSnapInputCache();
   }
 
   private applyMeasurementModelScale(): void {
@@ -2607,6 +2612,7 @@ export class ThreeModelPreview implements WorkbenchPreview {
 
   private setMeasurementTargetObject(object: Object3D | null, notify = true): void {
     this.clearMeasurementTargetHelper(false);
+    this.invalidateMeasurementSnapInputCache();
     const target = object && this.isObjectInLoadedRoot(object) ? object : null;
     this.measurementTargetObject = target;
     this.setMeasurementSnapKind(null, false);
@@ -2633,6 +2639,11 @@ export class ThreeModelPreview implements WorkbenchPreview {
     this.measurementTargetHelper.update();
   }
 
+  private invalidateMeasurementSnapInputCache(): void {
+    this.measurementSnapInputCache = null;
+    this.measurementSnapInputCacheTarget = null;
+  }
+
   private setMeasurementSnapKind(kind: MeasurementSnapKind | null, notify = true): void {
     if (this.measurementSnapKind === kind) return;
     this.measurementSnapKind = kind;
@@ -2692,14 +2703,12 @@ export class ThreeModelPreview implements WorkbenchPreview {
     return new Vector3(snapped.point.x, snapped.point.y, snapped.point.z);
   }
 
-  private createMeasurementGeometrySnapInput(): {
-    vertices: MeasurementSnapVertexCandidate[];
-    edges: MeasurementSnapEdgeCandidate[];
-    targetId?: string;
-    vertexRadius: number;
-  } | null {
+  private createMeasurementGeometrySnapInput(): MeasurementGeometrySnapInput | null {
     const target = this.measurementTargetObject;
     if (!target || !this.isObjectInLoadedRoot(target)) return null;
+    if (this.measurementSnapInputCache && this.measurementSnapInputCacheTarget === target) {
+      return this.measurementSnapInputCache;
+    }
     const renderables = this.getMeasurementTargetRenderables();
     if (renderables.length === 0) return null;
     const vertices: MeasurementSnapVertexCandidate[] = [];
@@ -2726,12 +2735,15 @@ export class ThreeModelPreview implements WorkbenchPreview {
     if (vertices.length === 0 && edges.length === 0) return null;
     const bounds = this.getMeasurementTargetBounds();
     const size = bounds ? getPreviewBoundsSize(bounds) : { x: 1, y: 1, z: 1 };
-    return {
+    const input = {
       vertices,
       edges,
       targetId,
       vertexRadius: Math.max(size.x, size.y, size.z, 0.001) * 0.045,
     };
+    this.measurementSnapInputCache = input;
+    this.measurementSnapInputCacheTarget = target;
+    return input;
   }
 
   private getMeasurementTargetRenderables(): ThreeRenderableObject[] {