Function updateMaterial

js/previewMaterial.js:426–457

(material, displacementTexture, settings)

    if (layerCount > 1) bumpLayer(1, PN, w.y, dhx, dhy, coverSum);
    if (layerCount > 2) bumpLayer(2, PN, w.z, dhx, dhy, coverSum);
    if (layerCount > 3) bumpLayer(3, PN, w.w, dhx, dhy, coverSum);
    coverSum = clamp(coverSum, 0.0, 1.0);

    vec3 dp1 = dFdx(vViewPos);
    vec3 dp2 = dFdy(vViewPos);

    vec3 T = dp1 - dot(dp1, N) * N;
    vec3 B = dp2 - dot(dp2, N) * N;
    float lenT = length(T);
    float lenB = length(B);
    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);

    // 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  = useDisplacement == 1
      ? 2.0 / posScale
      : 6.0 / posScale;

    vec3 bumpVec = N - bumpStr * (dhx * T + dhy * B);
    vec3 bumpN = length(bumpVec) > 1e-6 ? normalize(bumpVec) : N;

    // On fully masked faces the bump derivatives are zero, so bumpN falls
    // back to the flat face normal → faceted/static look.  Blend toward
    // the smooth interpolated normal so masked areas get smooth shading.
    vec3 smoothN = normalize(vSmoothNormal) * (gl_FrontFacing ? 1.0 : -1.0);
    bumpN = mix(smoothN, bumpN, coverSum);

    // ── Shading ───────────────────────────────────────────────────────────
    // Compute lighting identically for ALL surfaces using the teal base so
    // that specular highlights, diffuse response, and view-dependent shading
    // are perfectly consistent everywhere.  Mask tinting is applied AFTER
    // lighting as a colour blend so masked areas keep the same glossy look.
    vec3 tealBase      = vec3(0.22, 0.68, 0.68);