CNCKitchen · alan-polk · Apr 10, 2026
diff --git a/index.html b/index.html
@@ -193,6 +193,19 @@ <h2 data-i18n="sections.displacement">Displacement</h2>
       <section class="panel-section">
         <h2 data-i18n="sections.transform">Transform</h2>
 
+        <div class="form-row">
+          <label class="checkbox-label" for="fixed-world-texture"
+            data-i18n-title="tooltips.fixedWorldTexture"
+            title="Normalize UVs with a fixed length in millimetres instead of the part’s largest size, so the same settings yield similar physical texture size on different meshes.">
+            <input type="checkbox" id="fixed-world-texture" />
+            <span data-i18n="labels.fixedWorldTexture">Fixed texture scale (world mm)</span>
+          </label>
+        </div>
+        <div class="form-row" id="reference-extent-row" style="display:none">
+          <label for="reference-extent-mm" data-i18n="labels.referenceExtentMm" data-i18n-title="tooltips.referenceExtentMm" title="Millimetres used to normalize UV coordinates (before Scale U/V). Same value across parts for consistent pattern size.">Reference extent (mm)</label>
+          <input type="number" class="val" id="reference-extent-mm" value="200" min="0.1" max="10000" step="0.1" data-wheel-decimals="1" />
+        </div>
+
         <div class="form-row slider-row">
           <label for="scale-u" data-i18n="labels.scaleU">Scale U</label>
           <input type="range" id="scale-u" min="0" max="1000" step="1" value="435" />

diff --git a/js/displacement.js b/js/displacement.js
@@ -1,5 +1,5 @@
 import * as THREE from 'three';
-import { computeUV, getDominantCubicAxis, getCubicBlendWeights } from './mapping.js';
+import { computeUV, getDominantCubicAxis, getCubicBlendWeights, getReferenceExtent } from './mapping.js';
 
 /**
  * Apply displacement to every vertex of a non-indexed BufferGeometry.
@@ -320,7 +320,7 @@ export function applyDisplacement(geometry, imageData, imgWidth, imgHeight, sett
       const zaX = zoneAreaX[vid], zaY = zoneAreaY[vid], zaZ = zoneAreaZ[vid];
       const total = zaX + zaY + zaZ;
       if (total > 0) {
-        const md = Math.max(bounds.size.x, bounds.size.y, bounds.size.z, 1e-6);
+        const md = getReferenceExtent(settings, bounds);
         const rotRad = (settings.rotation ?? 0) * Math.PI / 180;
         let grey = 0;
         if (zaX > 0) { // X-dominant zone → YZ projection

diff --git a/js/i18n/de.js b/js/i18n/de.js
@@ -24,6 +24,10 @@ export default {
   "projection.planarXZ": "Planar XZ",
   "projection.planarYZ": "Planar YZ",
   "sections.transform": "Transformation",
+  "labels.fixedWorldTexture": "Feste Texturskalierung (mm)",
+  "tooltips.fixedWorldTexture": "Wenn aktiv, wird der UV-Abstand mit einer festen Länge in Millimetern statt der größten Bemaßung des Teils normiert — dieselben Einstellungen wirken auf verschiedenen Meshes ähnlich groß. Zylinder- und Kugelmodus nutzen weiterhin mesh-basierte Radien.",
+  "labels.referenceExtentMm": "Referenzmaß (mm)",
+  "tooltips.referenceExtentMm": "Millimetre zur Normierung der UV-Koordinaten pro Achse (vor Skalierung U/V). Gleicher Wert auf mehreren Teilen für einheitliche Mustergröße.",
   "labels.scaleU": "Skalierung U",
   "labels.scaleV": "Skalierung V",
   "labels.offsetU": "Versatz U",

diff --git a/js/i18n/en.js b/js/i18n/en.js
@@ -24,6 +24,10 @@ export default {
   "projection.planarXZ": "Planar XZ",
   "projection.planarYZ": "Planar YZ",
   "sections.transform": "Transform",
+  "labels.fixedWorldTexture": "Fixed texture scale (world mm)",
+  "tooltips.fixedWorldTexture": "When enabled, UV spacing uses a fixed length in millimetres instead of the part’s largest dimension, so the same settings look similar in physical size on different meshes. Cylindrical and spherical modes still use mesh-based radii.",
+  "labels.referenceExtentMm": "Reference extent (mm)",
+  "tooltips.referenceExtentMm": "Millimetres used to normalize UV coordinates along each axis (before Scale U/V). Use the same value across parts for consistent pattern size.",
   "labels.scaleU": "Scale U",
   "labels.scaleV": "Scale V",
   "labels.offsetU": "Offset U",

diff --git a/js/main.js b/js/main.js
@@ -76,6 +76,10 @@ const settings = {
   boundaryFalloff:  0,
   symmetricDisplacement: false,
   useDisplacement: false,
+  /** When true, UV normalization uses referenceExtentMm instead of each mesh's largest bbox edge. */
+  fixedWorldTextureScale: false,
+  /** Millimetres: one normalized UV span along an axis (before Scale U/V). */
+  referenceExtentMm: 200,
 };
 
 // ── Canvas filter support (Safari / iOS WebView don't support ctx.filter) ────
@@ -234,6 +238,15 @@ const boundaryFalloffSlider    = document.getElementById('boundary-falloff');
 const boundaryFalloffVal       = document.getElementById('boundary-falloff-val');
 const symmetricDispToggle    = document.getElementById('symmetric-displacement');
 const dispPreviewToggle      = document.getElementById('displacement-preview');
+const fixedWorldTextureToggle = document.getElementById('fixed-world-texture');
+const referenceExtentRow      = document.getElementById('reference-extent-row');
+const referenceExtentMmVal    = document.getElementById('reference-extent-mm');
+
+function refreshReferenceExtentUi() {
+  if (referenceExtentRow) {
+    referenceExtentRow.style.display = settings.fixedWorldTextureScale ? '' : 'none';
+  }
+}
 
 // ── Exclusion panel DOM refs ──────────────────────────────────────────────────
 const exclBrushBtn        = document.getElementById('excl-brush-btn');
@@ -374,6 +387,7 @@ document.getElementById('theme-toggle').addEventListener('click', () => {
 });
 
 wireEvents();
+refreshReferenceExtentUi();
 // Sync scale number inputs with the slider's initial position
 scaleUVal.value = posToScale(parseFloat(scaleUSlider.value));
 scaleVVal.value = posToScale(parseFloat(scaleVSlider.value));
@@ -580,6 +594,31 @@ function wireEvents() {
     }
   });
 
+  if (fixedWorldTextureToggle) {
+    fixedWorldTextureToggle.addEventListener('change', () => {
+      settings.fixedWorldTextureScale = fixedWorldTextureToggle.checked;
+      refreshReferenceExtentUi();
+      clearTimeout(previewDebounce); previewDebounce = setTimeout(updatePreview, 80);
+    });
+  }
+
+  function applyReferenceExtentFromInput() {
+    if (!referenceExtentMmVal) return;
+    let v = parseFloat(referenceExtentMmVal.value);
+    if (!Number.isFinite(v)) v = settings.referenceExtentMm;
+    v = Math.max(0.1, Math.min(10000, v));
+    settings.referenceExtentMm = v;
+    referenceExtentMmVal.value = v;
+    clearTimeout(previewDebounce); previewDebounce = setTimeout(updatePreview, 80);
+  }
+  if (referenceExtentMmVal) {
+    referenceExtentMmVal.addEventListener('change', applyReferenceExtentFromInput);
+    addFineWheelSupport(referenceExtentMmVal, (v) => {
+      referenceExtentMmVal.value = v;
+      applyReferenceExtentFromInput();
+    });
+  }
+
   linkSlider(offsetUSlider,   offsetUVal,   v => { settings.offsetU   = v; return v.toFixed(2); });
   linkSlider(offsetVSlider,   offsetVVal,   v => { settings.offsetV   = v; return v.toFixed(2); });
   linkSlider(rotationSlider,  rotationVal,  v => { settings.rotation  = v; return Math.round(v); });

diff --git a/js/mapping.js b/js/mapping.js
@@ -13,6 +13,21 @@ export const MODE_TRIPLANAR   = 5;
 export const MODE_CUBIC       = 6;
 
 const TWO_PI = Math.PI * 2;
+
+/**
+ * Millimetres used to normalize planar / triplanar / cubic UV coordinates.
+ * Default (fixed off): each mesh's largest bounding-box edge — pattern scales with part size.
+ * Fixed world scale: user `referenceExtentMm` — same profile yields similar physical pattern size on any mesh.
+ */
+export function getReferenceExtent(settings, bounds) {
+  const maxDim = Math.max(bounds.size.x, bounds.size.y, bounds.size.z);
+  const md = Math.max(maxDim, 1e-6);
+  if (settings.fixedWorldTextureScale) {
+    const ref = Number(settings.referenceExtentMm);
+    if (Number.isFinite(ref) && ref > 0) return ref;
+  }
+  return md;
+}
 const CUBIC_AXIS_EPSILON = 1e-4;
 
 export function getDominantCubicAxis(normal) {
@@ -114,8 +129,7 @@ export function computeUV(pos, normal, mode, settings, bounds) {
   const rotRad = (settings.rotation ?? 0) * Math.PI / 180;
   const cosR = Math.cos(rotRad);
   const sinR = Math.sin(rotRad);
-  const maxDim = Math.max(size.x, size.y, size.z);
-  const md     = Math.max(maxDim, 1e-6);
+  const md = getReferenceExtent(settings, bounds);
 
   let u = 0, v = 0;
 

diff --git a/js/previewMaterial.js b/js/previewMaterial.js
@@ -39,6 +39,8 @@ const sharedGLSL = /* glsl */`
   uniform int       symmetricDisplacement;
   uniform int       useDisplacement;
   uniform vec2      textureAspect;
+  uniform int       useFixedReference;
+  uniform float     referenceExtentMm;
 
   const float PI     = 3.14159265358979;
   const float TWO_PI = 6.28318530717959;
@@ -99,6 +101,9 @@ const sharedGLSL = /* glsl */`
     vec3 rel = pos - boundsCenter;
     float maxDim = max(boundsSize.x, max(boundsSize.y, boundsSize.z));
     float md = max(maxDim, 1e-4);
+    if (useFixedReference > 0) {
+      md = max(referenceExtentMm, 1e-4);
+    }
 
     if (mappingMode == 0) {
       return sampleMap(vec2((pos.x - boundsMin.x) / md, (pos.y - boundsMin.y) / md));
@@ -435,6 +440,8 @@ export function updateMaterial(material, displacementTexture, settings) {
   u.useDisplacement.value         = settings.useDisplacement         ? 1 : 0;
   u.textureAspect.value.set(settings.textureAspectU ?? 1, settings.textureAspectV ?? 1);
   u.boundaryFalloffDist.value       = settings.boundaryFalloff           ?? 0.0;
+  u.useFixedReference.value         = settings.fixedWorldTextureScale ? 1 : 0;
+  u.referenceExtentMm.value         = Math.max(Number(settings.referenceExtentMm) || 200, 1e-4);
 }
 
 // ── Internal ──────────────────────────────────────────────────────────────────
@@ -467,6 +474,8 @@ function buildUniforms(tex, settings) {
     boundaryEdgeCount:        { value: 0 },
     boundaryEdgeTexWidth:     { value: 1.0 },
     boundaryFalloffDist:        { value: settings.boundaryFalloff ?? 0.0 },
+    useFixedReference:          { value: settings.fixedWorldTextureScale ? 1 : 0 },
+    referenceExtentMm:          { value: Math.max(Number(settings.referenceExtentMm) || 200, 1e-4) },
   };
 }