Added a 3D Preview

index.html

@@ -161,6 +161,14 @@
             <span data-i18n="labels.symmetricDisplacement">Symmetric displacement ⓘ</span>
           </label>
         </div>
+        <div class="form-row">
+          <label class="checkbox-label" for="displacement-preview"
+            data-i18n-title="tooltips.displacementPreview"
+            title="Subdivides the mesh and displaces vertices in real-time so you can judge the actual depth. GPU-intensive on complex models.">
+            <input type="checkbox" id="displacement-preview" />
+            <span data-i18n="labels.displacementPreview">3D Preview ⓘ</span>
+          </label>
+        </div>
       </section>
 
       <!-- Transform -->

js/displacement.js

@@ -251,7 +251,7 @@ export function applyDisplacement(geometry, imageData, imgWidth, imgHeight, sett
     const isSealedBoundary = !isFaceExcluded && excludedPosSet && excludedPosSet.has(k);
     const mf         = maskedFracMap.get(k) || [0, 1];
     const maskedFrac = mf[1] > 0 ? mf[0] / mf[1] : 0;
-    const centeredGrey = settings.symmetricDisplacement ? (grey - 0.5) * 2.0 : grey;
+    const centeredGrey = settings.symmetricDisplacement ? (grey - 0.5) : grey;
     const disp = (isFaceExcluded || isSealedBoundary) ? 0 : (1 - maskedFrac) * centeredGrey * settings.amplitude;
 
     const newX = tmpPos.x + sn[0] * disp;

js/i18n.js

@@ -96,6 +96,11 @@ export const TRANSLATIONS = {
     'labels.symmetricDisplacement':  'Symmetric displacement \u24d8',
     'tooltips.symmetricDisplacement':'When on, 50% grey = no displacement; white pushes out, black pushes in. Keeps part volume roughly constant.',
 
+    // Displacement preview
+    'labels.displacementPreview':    '3D Preview \u24d8',
+    'tooltips.displacementPreview':  'Subdivides the mesh and displaces vertices in real-time so you can judge the actual depth. GPU-intensive on complex models.',
+    'progress.subdividingPreview':   'Preparing preview\u2026',
+
     // Amplitude overlap warning
     'warnings.amplitudeOverlap':     '\u26a0 Amplitude exceeds 10% of the smallest model dimension \u2014 geometry overlaps may occur in the exported STL.',
 
@@ -229,6 +234,11 @@ export const TRANSLATIONS = {
     'labels.symmetricDisplacement':  'Symmetrische Verschiebung \u24d8',
     'tooltips.symmetricDisplacement':'Wenn aktiv: 50% Grau = keine Verschiebung; Weiß nach außen, Schwarz nach innen. H\u00e4lt das Volumen des Teils in etwa konstant.',
 
+    // Displacement preview
+    'labels.displacementPreview':    '3D-Vorschau \u24d8',
+    'tooltips.displacementPreview':  'Unterteilt das Netz und verschiebt Punkte in Echtzeit, damit die tats\u00e4chliche Tiefe sichtbar wird. GPU-intensiv bei komplexen Modellen.',
+    'progress.subdividingPreview':   'Vorschau wird vorbereitet\u2026',
+
     // Amplitude overlap warning
     'warnings.amplitudeOverlap':     '\u26a0 Amplitude \u00fcberschreitet 10% der kleinsten Modellabmessung \u2014 beim Export k\u00f6nnen Geometrie\u00fcberschneidungen auftreten.',
 

js/main.js

@@ -1,5 +1,5 @@
 import * as THREE from 'three';
-import { initViewer, loadGeometry, setMeshMaterial, setWireframe,
+import { initViewer, loadGeometry, setMeshMaterial, setMeshGeometry, setWireframe,
          getControls, getCamera, getCurrentMesh,
          setExclusionOverlay, setHoverPreview, setViewerTheme } from './viewer.js';
 import { loadSTLFile, computeBounds, getTriangleCount }  from './stlLoader.js';
@@ -53,8 +53,13 @@ const settings = {
   mappingBlend:     1,
   seamBandWidth:    0.5,
   symmetricDisplacement: false,
+  useDisplacement: false,
 };
 
+// ── Displacement preview state ────────────────────────────────────────────────
+let dispPreviewGeometry  = null;   // subdivided geometry with smoothNormal attribute
+let dispPreviewBusy      = false;  // true while async subdivision is running
+
 // ── DOM refs ──────────────────────────────────────────────────────────────────
 
 const canvas         = document.getElementById('viewport');
@@ -104,6 +109,7 @@ const seamBlendVal           = document.getElementById('seam-blend-val');
 const seamBandWidthSlider    = document.getElementById('seam-band-width');
 const seamBandWidthVal       = document.getElementById('seam-band-width-val');
 const symmetricDispToggle    = document.getElementById('symmetric-displacement');
+const dispPreviewToggle      = document.getElementById('displacement-preview');
 
 // ── Exclusion panel DOM refs ──────────────────────────────────────────────────
 const exclBrushBtn        = document.getElementById('excl-brush-btn');
@@ -322,6 +328,10 @@ function wireEvents() {
     updatePreview();
   });
 
+  dispPreviewToggle.addEventListener('change', () => {
+    toggleDisplacementPreview(dispPreviewToggle.checked);
+  });
+
   // ── Export ──
   exportBtn.addEventListener('click', () => {
     if (sessionStorage.getItem('stlt-no-sponsor') === '1') {
@@ -695,6 +705,11 @@ function loadDefaultCube() {
   loadGeometry(geo);
   dropHint.classList.add('hidden');
 
+  // Reset displacement preview
+  if (dispPreviewGeometry) { dispPreviewGeometry.dispose(); dispPreviewGeometry = null; }
+  settings.useDisplacement = false;
+  dispPreviewToggle.checked = false;
+
   // Reset exclusion state
   excludedFaces     = new Set();
   exclusionTool     = null;
@@ -763,6 +778,11 @@ async function handleSTL(file) {
     loadGeometry(geometry);
     dropHint.classList.add('hidden');
 
+    // Reset displacement preview for the new mesh
+    if (dispPreviewGeometry) { dispPreviewGeometry.dispose(); dispPreviewGeometry = null; }
+    settings.useDisplacement = false;
+    dispPreviewToggle.checked = false;
+
     // Reset exclusion state for the new mesh
     excludedFaces     = new Set();
     exclusionTool     = null;
@@ -842,9 +862,14 @@ function updatePreview() {
     return;
   }
 
+  // Choose geometry: subdivided preview (with smoothNormal attribute) or original
+  const activeGeo = (settings.useDisplacement && dispPreviewGeometry)
+    ? dispPreviewGeometry
+    : currentGeometry;
+
   if (!previewMaterial) {
     previewMaterial = createPreviewMaterial(activeMapEntry.texture, fullSettings);
-    loadGeometry(currentGeometry, previewMaterial);
+    loadGeometry(activeGeo, previewMaterial);
   } else {
     updateMaterial(previewMaterial, activeMapEntry.texture, fullSettings);
   }
@@ -852,6 +877,138 @@ function updatePreview() {
   exportBtn.disabled = false;
 }
 
+// ── Displacement preview ──────────────────────────────────────────────────────
+
+/**
+ * Compute area-weighted smooth normals for a non-indexed geometry and store
+ * them as a `smoothNormal` vec3 attribute.  Every copy of the same position
+ * gets the same averaged normal so vertex-shader displacement is watertight.
+ */
+function addSmoothNormals(geometry) {
+  const pos   = geometry.attributes.position.array;
+  const count = geometry.attributes.position.count;
+
+  const QUANT = 1e4;
+  const key = (x, y, z) =>
+    `${Math.round(x * QUANT)}_${Math.round(y * QUANT)}_${Math.round(z * QUANT)}`;
+
+  // Accumulate area-weighted face normals per unique position
+  const nrmMap = new Map();
+  const vA = new THREE.Vector3(), vB = new THREE.Vector3(), vC = new THREE.Vector3();
+  const e1 = new THREE.Vector3(), e2 = new THREE.Vector3(), fn = new THREE.Vector3();
+
+  for (let i = 0; i < count; i += 3) {
+    vA.set(pos[i * 3], pos[i * 3 + 1], pos[i * 3 + 2]);
+    vB.set(pos[(i + 1) * 3], pos[(i + 1) * 3 + 1], pos[(i + 1) * 3 + 2]);
+    vC.set(pos[(i + 2) * 3], pos[(i + 2) * 3 + 1], pos[(i + 2) * 3 + 2]);
+    e1.subVectors(vB, vA);
+    e2.subVectors(vC, vA);
+    fn.crossVectors(e1, e2); // length = 2 × triangle area
+    const area = fn.length();
+    if (area < 1e-12) continue;
+    fn.divideScalar(area); // unit face normal
+    for (const v of [vA, vB, vC]) {
+      const k = key(v.x, v.y, v.z);
+      const prev = nrmMap.get(k);
+      if (prev) {
+        prev[0] += fn.x * area;
+        prev[1] += fn.y * area;
+        prev[2] += fn.z * area;
+      } else {
+        nrmMap.set(k, [fn.x * area, fn.y * area, fn.z * area]);
+      }
+    }
+  }
+
+  // Normalize accumulated normals
+  for (const n of nrmMap.values()) {
+    const len = Math.sqrt(n[0] * n[0] + n[1] * n[1] + n[2] * n[2]);
+    if (len > 1e-12) { n[0] /= len; n[1] /= len; n[2] /= len; }
+  }
+
+  // Write smoothNormal attribute
+  const sn = new Float32Array(count * 3);
+  for (let i = 0; i < count; i++) {
+    const k = key(pos[i * 3], pos[i * 3 + 1], pos[i * 3 + 2]);
+    const n = nrmMap.get(k);
+    if (n) { sn[i * 3] = n[0]; sn[i * 3 + 1] = n[1]; sn[i * 3 + 2] = n[2]; }
+    else   { sn[i * 3] = 0; sn[i * 3 + 1] = 0; sn[i * 3 + 2] = 1; }
+  }
+  geometry.setAttribute('smoothNormal', new THREE.Float32BufferAttribute(sn, 3));
+}
+
+/**
+ * Toggle displacement preview on/off.
+ * When enabled: subdivides the current geometry to a moderate resolution,
+ * computes smooth normals, and switches the viewer to the subdivided
+ * geometry with vertex-shader displacement.
+ * When disabled: reverts to the original geometry with bump-only preview.
+ */
+async function toggleDisplacementPreview(enable) {
+  settings.useDisplacement = enable;
+
+  if (!enable) {
+    // Revert to original geometry with bump-only shading.
+    if (currentGeometry && previewMaterial) {
+      updateMaterial(previewMaterial, activeMapEntry?.texture, { ...settings, bounds: currentBounds });
+      setMeshGeometry(currentGeometry);
+    }
+    // Dispose the subdivided preview geometry (no longer on the mesh)
+    if (dispPreviewGeometry) {
+      dispPreviewGeometry.dispose();
+      dispPreviewGeometry = null;
+    }
+    return;
+  }
+
+  // Need a model and texture to subdivide
+  if (!currentGeometry || !currentBounds || !activeMapEntry) {
+    dispPreviewToggle.checked = false;
+    settings.useDisplacement = false;
+    return;
+  }
+
+  if (dispPreviewBusy) return;
+  dispPreviewBusy = true;
+
+  try {
+    // Choose a preview edge length: coarser than export for performance.
+    // Target ~maxDim/80 so a 50 mm cube gets ~0.6 mm edges → ~100 k triangles.
+    const maxDim = Math.max(currentBounds.size.x, currentBounds.size.y, currentBounds.size.z);
+    const previewEdge = Math.max(0.1, maxDim / 80);
+
+    await yieldFrame();
+
+    const { geometry: subdivided } = await subdivide(
+      currentGeometry, previewEdge, null, null
+    );
+
+    addSmoothNormals(subdivided);
+
+    // Dispose previous preview geometry if any
+    if (dispPreviewGeometry) dispPreviewGeometry.dispose();
+    dispPreviewGeometry = subdivided;
+
+    // Force material recreation so it binds the new geometry with smoothNormal
+    if (previewMaterial) {
+      previewMaterial.dispose();
+      previewMaterial = null;
+    }
+    const fullSettings = { ...settings, bounds: currentBounds };
+    previewMaterial = createPreviewMaterial(activeMapEntry.texture, fullSettings);
+    setMeshGeometry(dispPreviewGeometry);
+    setMeshMaterial(previewMaterial);
+
+
+  } catch (err) {
+    console.error('Displacement preview failed:', err);
+    dispPreviewToggle.checked = false;
+    settings.useDisplacement = false;
+  } finally {
+    dispPreviewBusy = false;
+  }
+}
+
 // ── Export pipeline ───────────────────────────────────────────────────────────
 
 /**

js/previewMaterial.js

@@ -11,38 +11,17 @@ export const MODE_CUBIC       = 6;
 
 // ── GLSL source ──────────────────────────────────────────────────────────────
 //
-// Preview strategy: NO vertex displacement.
-// All UV projection is done in the fragment shader so the underlying mesh
-// geometry is never modified.  The displacement map is visualised via
-// per-fragment bump mapping (perturbing the shading normal from screen-space
-// height derivatives).  `amplitude` scales the bump intensity only.
-
-const vertexShader = /* glsl */`
-  precision highp float;
-
-  varying vec3 vModelPos;    // model-space position  → UV computation in fragment
-  varying vec3 vModelNormal; // model-space normal    → stable UV blending (triplanar/cubic)
-  varying vec3 vViewPos;     // view-space position   → TBN & specular
-  varying vec3 vNormal;      // view-space normal     → lighting
-
-  void main() {
-    vModelPos = position;
-    // Guard against degenerate zero-length normals (non-manifold / multi-body STLs
-    // can produce averaged-to-zero normals at shared vertices between opposing bodies).
-    // normalize(vec3(0)) is undefined in GLSL and produces NaN on most GPUs,
-    // which then turns the entire fragment black.
-    vec3 safeN   = length(normal) > 1e-6 ? normalize(normal) : vec3(0.0, 0.0, 1.0);
-    vModelNormal = safeN;
-    vec4 mvPos   = modelViewMatrix * vec4(position, 1.0);
-    vViewPos     = mvPos.xyz;
-    vNormal      = normalize(normalMatrix * safeN);
-    gl_Position  = projectionMatrix * mvPos;
-  }
-`;
-
-const fragmentShader = /* glsl */`
-  precision highp float;
+// Preview strategy, two modes:
+//   1. Bump-only (default):  UV projection & bump mapping in the fragment shader.
+//      The underlying geometry is never modified; amplitude scales bump intensity.
+//   2. Displacement preview: The vertex shader samples the same displacement
+//      texture and physically moves each vertex along its smooth normal.
+//      Fragment shader adds reduced bump mapping for sub-vertex detail.
+//
+// The shared GLSL block below is included in BOTH shaders so UV math,
+// projection modes, and texture sampling stay identical.
 
+const sharedGLSL = /* glsl */`
   uniform sampler2D displacementMap;
   uniform int       mappingMode;
   uniform vec2      scaleUV;
@@ -52,16 +31,12 @@ const fragmentShader = /* glsl */`
   uniform vec3      boundsMin;
   uniform vec3      boundsSize;
   uniform vec3      boundsCenter;
-  uniform float     bottomAngleLimit; // degrees from horizontal; 0 = disabled
-  uniform float     topAngleLimit;    // degrees from horizontal; 0 = disabled
-  uniform float     mappingBlend;     // 0 = sharp seams, 1 = fully blended
-  uniform float     seamBandWidth;    // width of the blend zone near cube-face seams
-  uniform int       symmetricDisplacement; // 1 = remap [0,1]→[-1,1] so 50% grey = no disp
-
-  varying vec3 vModelPos;
-  varying vec3 vModelNormal;
-  varying vec3 vViewPos;
-  varying vec3 vNormal;
+  uniform float     bottomAngleLimit;
+  uniform float     topAngleLimit;
+  uniform float     mappingBlend;
+  uniform float     seamBandWidth;
+  uniform int       symmetricDisplacement;
+  uniform int       useDisplacement;
 
   const float PI     = 3.14159265358979;
   const float TWO_PI = 6.28318530717959;
@@ -108,7 +83,6 @@ const fragmentShader = /* glsl */`
   // Sample after applying scale + tiling
   float sampleMap(vec2 rawUV) {
     vec2 uv = rawUV / scaleUV + offsetUV;
-    // rotate around tile centre
     float c = cos(rotation); float s = sin(rotation);
     uv -= 0.5;
     uv  = vec2(c * uv.x - s * uv.y, s * uv.x + c * uv.y);
@@ -116,24 +90,14 @@ const fragmentShader = /* glsl */`
     return texture2D(displacementMap, uv).r;
   }
 
-  // Height at this fragment for all projection modes.
-  // Uses vModelPos / vModelNormal (model-space) so UV is stable as the camera orbits.
-  float getHeight() {
-    vec3 pos = vModelPos;
-    vec3 MN  = vModelNormal;  // smooth interpolated normal → shading only
+  // Compute displacement height at a world-space point.
+  // projN  = face-stable projection normal (for axis selection)
+  // blendN = smooth / interpolated normal  (for blend weights)
+  float computeHeightAtPoint(vec3 pos, vec3 projN, vec3 blendN) {
     vec3 rel = pos - boundsCenter;
     float maxDim = max(boundsSize.x, max(boundsSize.y, boundsSize.z));
     float md = max(maxDim, 1e-4);
 
-    // Face-stable projection normal: cross product of screen-space position
-    // derivatives is CONSTANT within a triangle (unlike the interpolated
-    // vModelNormal), eliminating within-face texture z-fighting at seam
-    // boundaries in cubic / triplanar mapping. Falls back to MN if degenerate.
-    vec3 _dpx = dFdx(vModelPos);
-    vec3 _dpy = dFdy(vModelPos);
-    vec3 _fN  = cross(_dpx, _dpy);
-    vec3 PN   = length(_fN) > 1e-10 ? normalize(_fN) : MN;
-
     if (mappingMode == 0) {
       return sampleMap(vec2((pos.x - boundsMin.x) / md, (pos.y - boundsMin.y) / md));
 
@@ -144,62 +108,119 @@ const fragmentShader = /* glsl */`
       return sampleMap(vec2((pos.y - boundsMin.y) / md, (pos.z - boundsMin.z) / md));
 
     } else if (mappingMode == 3) {
-      // Cylindrical around Z axis (Z is up) with blendable side↔cap transition.
       float r = max(boundsSize.x, boundsSize.y) * 0.5;
       float C = TWO_PI * max(r, 1e-4);
       float hSide = sampleMap(vec2(atan(rel.y, rel.x) / TWO_PI + 0.5,
                                    (pos.z - boundsMin.z) / C));
       if (mappingBlend < 0.001) return hSide;
       float blendHalf = mappingBlend * 0.20;
-      float capW = smoothstep(0.7 - blendHalf, 0.7 + blendHalf, abs(vModelNormal.z));
+      float capW = smoothstep(0.7 - blendHalf, 0.7 + blendHalf, abs(blendN.z));
       float hCap  = sampleMap(vec2(rel.x / C + 0.5, rel.y / C + 0.5));
       return mix(hSide, hCap, capW);
 
     } else if (mappingMode == 4) {
-      // Spherical — Z is up
       float r     = length(rel);
       float phi   = acos(clamp(rel.z / max(r, 1e-4), -1.0, 1.0));
       float theta = atan(rel.y, rel.x);
       return sampleMap(vec2(theta / TWO_PI + 0.5, phi / PI));
 
     } else if (mappingMode == 5) {
-      // Triplanar – smooth blend using face-stable projection normal (constant per triangle)
-      vec3 blend = abs(PN);
+      vec3 blend = abs(projN);
       blend = pow(blend, vec3(4.0));
       blend /= dot(blend, vec3(1.0)) + 1e-4;
-
       float hXY = sampleMap(vec2((pos.x - boundsMin.x) / md, (pos.y - boundsMin.y) / md));
       float hXZ = sampleMap(vec2((pos.x - boundsMin.x) / md, (pos.z - boundsMin.z) / md));
       float hYZ = sampleMap(vec2((pos.y - boundsMin.y) / md, (pos.z - boundsMin.z) / md));
-
       return hXY * blend.z + hXZ * blend.y + hYZ * blend.x;
 
     } else {
-      // Cubic (box) – use smooth normals for blend weights so high blend values
-      // can hide seams, but fall back to the face-stable triangle normal when
-      // the triangle sits on an ambiguous near-45° tie.
       float hYZ = sampleMap(vec2((pos.y - boundsMin.y) / md, (pos.z - boundsMin.z) / md));
       float hXZ = sampleMap(vec2((pos.x - boundsMin.x) / md, (pos.z - boundsMin.z) / md));
       float hXY = sampleMap(vec2((pos.x - boundsMin.x) / md, (pos.y - boundsMin.y) / md));
-      vec3 blendN = vModelNormal;
-      vec3 absFaceN = abs(PN);
+      vec3 bN = blendN;
+      vec3 absFaceN = abs(projN);
       float facePrimary = max(absFaceN.x, max(absFaceN.y, absFaceN.z));
-      float faceSecondary = absFaceN.x + absFaceN.y + absFaceN.z - facePrimary - min(absFaceN.x, min(absFaceN.y, absFaceN.z));
-      if (facePrimary - faceSecondary <= CUBIC_AXIS_EPSILON) blendN = PN;
-      vec3 wts = cubicBlendWeights(blendN);
+      float faceSecondary = absFaceN.x + absFaceN.y + absFaceN.z - facePrimary
+                          - min(absFaceN.x, min(absFaceN.y, absFaceN.z));
+      if (facePrimary - faceSecondary <= CUBIC_AXIS_EPSILON) bN = projN;
+      vec3 wts = cubicBlendWeights(bN);
       return hYZ * wts.x + hXZ * wts.y + hXY * wts.z;
     }
   }
+`;
+
+const vertexShader = /* glsl */`
+  precision highp float;
+  ${sharedGLSL}
+
+  attribute vec3 smoothNormal;
+
+  varying vec3 vModelPos;    // ORIGINAL model-space position → UV computation in fragment
+  varying vec3 vModelNormal; // model-space face normal       → stable UV blending
+  varying vec3 vViewPos;     // view-space position (possibly displaced) → TBN & specular
+  varying vec3 vNormal;      // view-space normal → lighting
+
+  void main() {
+    vec3 safeN = length(normal) > 1e-6 ? normalize(normal) : vec3(0.0, 0.0, 1.0);
+    vec3 pos = position;
+
+    if (useDisplacement == 1) {
+      // Sample displacement texture using the same UV math as the fragment shader
+      float h = computeHeightAtPoint(position, safeN, safeN);
+      if (symmetricDisplacement == 1) h = h - 0.5;
+
+      // Surface angle masking (same logic as fragment shader)
+      float surfaceAngle = degrees(acos(clamp(abs(safeN.z), 0.0, 1.0)));
+      float maskBlend = 1.0;
+      float FADE = 15.0;
+      if (safeN.z <  0.0 && bottomAngleLimit >= 1.0)
+        maskBlend = min(maskBlend, smoothstep(bottomAngleLimit, bottomAngleLimit + FADE, surfaceAngle));
+      if (safeN.z >= 0.0 && topAngleLimit >= 1.0)
+        maskBlend = min(maskBlend, smoothstep(topAngleLimit, topAngleLimit + FADE, surfaceAngle));
+      h = mix(0.0, h, maskBlend);
+
+      // Displace along smooth normal so all copies of the same position
+      // arrive at the same point (watertight, no cracks).
+      vec3 sN = length(smoothNormal) > 1e-6 ? normalize(smoothNormal) : safeN;
+      pos = position + sN * h * amplitude;
+    }
+
+    // Always pass the ORIGINAL position for UV computation in the fragment shader.
+    vModelPos    = position;
+    vModelNormal = safeN;
+    vec4 mvPos   = modelViewMatrix * vec4(pos, 1.0);
+    vViewPos     = mvPos.xyz;
+    vNormal      = normalize(normalMatrix * safeN);
+    gl_Position  = projectionMatrix * mvPos;
+  }
+`;
+
+const fragmentShader = /* glsl */`
+  precision highp float;
+  ${sharedGLSL}
+
+  varying vec3 vModelPos;
+  varying vec3 vModelNormal;
+  varying vec3 vViewPos;
+  varying vec3 vNormal;
+
+  // Fragment-only wrapper: compute face-stable projection normal via dFdx
+  // then delegate to the shared height function.
+  float getHeight() {
+    vec3 _dpx = dFdx(vModelPos);
+    vec3 _dpy = dFdy(vModelPos);
+    vec3 _fN  = cross(_dpx, _dpy);
+    vec3 PN   = length(_fN) > 1e-10 ? normalize(_fN) : vModelNormal;
+    return computeHeightAtPoint(vModelPos, PN, vModelNormal);
+  }
 
   void main() {
     // Flip normal for back faces so flipped-winding geometry still lights correctly.
     vec3 N = normalize(vNormal) * (gl_FrontFacing ? 1.0 : -1.0);
     float h = getHeight();
-    if (symmetricDisplacement == 1) h = h * 2.0 - 1.0; // remap [0,1]→[-1,1]: 0.5 grey = zero
+    if (symmetricDisplacement == 1) h = h - 0.5;
 
-    // ── Surface angle masking (FDM: suppress texture on near-horizontal faces) ────
-    // Use a 15° smoothstep fade above the threshold so the bump tapers gradually
-    // into the masked region rather than cutting off abruptly at the boundary edge.
+    // ── Surface angle masking ─────────────────────────────────────────────
     float surfaceAngle = degrees(acos(clamp(abs(vModelNormal.z), 0.0, 1.0)));
     float maskBlend = 1.0;
     float FADE = 15.0;
@@ -207,7 +228,7 @@ const fragmentShader = /* glsl */`
       maskBlend = min(maskBlend, smoothstep(bottomAngleLimit, bottomAngleLimit + FADE, surfaceAngle));
     if (vModelNormal.z >= 0.0 && topAngleLimit >= 1.0)
       maskBlend = min(maskBlend, smoothstep(topAngleLimit, topAngleLimit + FADE, surfaceAngle));
-    h = mix(0.0, h, maskBlend); // blend toward neutral (zero-gradient → no bump)
+    h = mix(0.0, h, maskBlend);
 
     // ── Bump mapping via screen-space height derivatives ──────────────────
     float dhx = dFdx(h);
@@ -223,10 +244,12 @@ const fragmentShader = /* glsl */`
     T = lenT > 1e-5 ? T / lenT : vec3(1.0, 0.0, 0.0);
     B = lenB > 1e-5 ? B / lenB : vec3(0.0, 1.0, 0.0);
 
-    // Bump strength normalised by screen-space position derivative so
-    // the effect is independent of zoom level.
+    // When vertex displacement is active, reduce bump strength: the macro shape
+    // is already physical; bump only adds sub-vertex fine detail.
     float posScale = max(length(dp1) + length(dp2), 1e-6);
-    float bumpStr  = amplitude * 6.0 / posScale;
+    float bumpStr  = useDisplacement == 1
+      ? amplitude * 2.0 / posScale
+      : amplitude * 6.0 / posScale;
 
     vec3 bumpVec = N - bumpStr * (dhx * T + dhy * B);
     vec3 bumpN = length(bumpVec) > 1e-6 ? normalize(bumpVec) : N;
@@ -293,6 +316,7 @@ export function updateMaterial(material, displacementTexture, settings) {
   u.mappingBlend.value            = settings.mappingBlend            ?? 0.0;
   u.seamBandWidth.value           = settings.seamBandWidth           ?? 0.35;
   u.symmetricDisplacement.value   = settings.symmetricDisplacement   ? 1 : 0;
+  u.useDisplacement.value         = settings.useDisplacement         ? 1 : 0;
 }
 
 // ── Internal ──────────────────────────────────────────────────────────────────
@@ -318,6 +342,7 @@ function buildUniforms(tex, settings) {
     mappingBlend:             { value: settings.mappingBlend            ?? 0.0 },
     seamBandWidth:            { value: settings.seamBandWidth            ?? 0.35 },
     symmetricDisplacement:    { value: settings.symmetricDisplacement   ? 1 : 0 },
+    useDisplacement:          { value: settings.useDisplacement         ? 1 : 0 },
   };
 }
 

js/viewer.js

@@ -300,6 +300,26 @@ export function setMeshMaterial(material) {
   });
 }
 
+/**
+ * Swap only the geometry on the current mesh, keeping material and camera.
+ * Rebuilds wireframe if visible.  Does NOT reset camera or grid.
+ * The caller is responsible for disposing old geometry if needed.
+ * @param {THREE.BufferGeometry} geometry
+ */
+export function setMeshGeometry(geometry) {
+  if (!currentMesh) return;
+  if (!geometry.attributes.normal) geometry.computeVertexNormals();
+  currentMesh.geometry = geometry;
+  // Rebuild wireframe overlay to match the new geometry
+  if (wireframeLines) {
+    meshGroup.remove(wireframeLines);
+    wireframeLines.geometry.dispose();
+    wireframeLines.material.dispose();
+    wireframeLines = null;
+  }
+  if (wireframeVisible) _buildWireframe(geometry);
+}
+
 /**
  * Get the grid object so callers can adjust position.
  */