Update from book source. No functional changes.

s/BumpEvalContext/NormalBumpEvalContext/
Factor Bump() into BumpMap() and NormalMap()

src/pbrt/base/material.h

@@ -64,10 +64,10 @@ class Material
     template <typename TextureEvaluator>
     PBRT_CPU_GPU inline bool CanEvaluateTextures(TextureEvaluator texEval) const;
 
-    PBRT_CPU_GPU inline FloatTexture GetDisplacement() const;
-
     PBRT_CPU_GPU inline const Image *GetNormalMap() const;
 
+    PBRT_CPU_GPU inline FloatTexture GetDisplacement() const;
+
     PBRT_CPU_GPU inline bool HasSubsurfaceScattering() const;
 };
 

src/pbrt/interaction.cpp

@@ -154,7 +154,9 @@ RayDifferential SurfaceInteraction::SpawnRay(const RayDifferential &rayi,
 BSDF SurfaceInteraction::GetBSDF(const RayDifferential &ray, SampledWavelengths &lambda,
                                  Camera camera, ScratchBuffer &scratchBuffer,
                                  Sampler sampler) {
+    // Estimate $(u,v)$ and position differentials at intersection point
     ComputeDifferentials(ray, camera, sampler.SamplesPerPixel());
+
     // Resolve _MixMaterial_ if necessary
     while (material.Is<MixMaterial>()) {
         MixMaterial *mix = material.CastOrNullptr<MixMaterial>();
@@ -165,14 +167,19 @@ BSDF SurfaceInteraction::GetBSDF(const RayDifferential &ray, SampledWavelengths
     if (!material)
         return {};
 
-    // Evaluate bump map and compute shading normal
+    // Evaluate normal or bump map, if present
     FloatTexture displacement = material.GetDisplacement();
     const Image *normalMap = material.GetNormalMap();
     if (displacement || normalMap) {
+        // Get shading $\dpdu$ and $\dpdv$ using normal or bump map
         Vector3f dpdu, dpdv;
-        Bump(UniversalTextureEvaluator(), displacement, normalMap, *this, &dpdu, &dpdv);
-        SetShadingGeometry(Normal3f(Normalize(Cross(dpdu, dpdv))), dpdu, dpdv,
-                           shading.dndu, shading.dndv, false);
+        if (normalMap)
+            NormalMap(normalMap, *this, &dpdu, &dpdv);
+        else
+            BumpMap(UniversalTextureEvaluator(), displacement, *this, &dpdu, &dpdv);
+
+        Normal3f ns(Normalize(Cross(dpdu, dpdv)));
+        SetShadingGeometry(ns, dpdu, dpdv, shading.dndu, shading.dndv, false);
     }
 
     // Return BSDF for surface interaction

src/pbrt/materials.cpp

@@ -30,12 +30,13 @@ std::string MaterialEvalContext::ToString() const {
                         TextureEvalContext::ToString(), wo, ns, dpdus);
 }
 
-std::string BumpEvalContext::ToString() const {
-    return StringPrintf("[ BumpEvalContext p: %s uv: %s shading.n: %s shading.dpdu: %s "
-                        "shading.dpdv: %s shading.dndu: %s shading.dndv: %s dudx: %f "
-                        "dudy: %f dvdx: %f dvdy: %f dpdx: %s dpdy: %s faceIndex: %d ]",
-                        p, uv, shading.n, shading.dpdu, shading.dpdv, shading.dndu,
-                        shading.dndv, dudx, dudy, dvdx, dvdy, dpdx, dpdy, faceIndex);
+std::string NormalBumpEvalContext::ToString() const {
+    return StringPrintf(
+        "[ NormalBumpEvalContext p: %s uv: %s shading.n: %s shading.dpdu: %s "
+        "shading.dpdv: %s shading.dndu: %s shading.dndv: %s dudx: %f "
+        "dudy: %f dvdx: %f dvdy: %f dpdx: %s dpdy: %s faceIndex: %d ]",
+        p, uv, shading.n, shading.dpdu, shading.dpdv, shading.dndu, shading.dndv, dudx,
+        dudy, dvdx, dvdy, dpdx, dpdy, faceIndex);
 }
 
 // DielectricMaterial Method Definitions

src/pbrt/materials.h

@@ -38,12 +38,12 @@ struct MaterialEvalContext : public TextureEvalContext {
     Vector3f dpdus;
 };
 
-// BumpEvalContext Definition
-struct BumpEvalContext {
-    // BumpEvalContext Public Methods
-    BumpEvalContext() = default;
+// NormalBumpEvalContext Definition
+struct NormalBumpEvalContext {
+    // NormalBumpEvalContext Public Methods
+    NormalBumpEvalContext() = default;
     PBRT_CPU_GPU
-    BumpEvalContext(const SurfaceInteraction &si)
+    NormalBumpEvalContext(const SurfaceInteraction &si)
         : p(si.p()),
           uv(si.uv),
           n(si.n),
@@ -68,7 +68,7 @@ struct BumpEvalContext {
                                   faceIndex);
     }
 
-    // BumpEvalContext Public Members
+    // NormalBumpEvalContext Public Members
     Point3f p;
     Point2f uv;
     Normal3f n;
@@ -82,56 +82,59 @@ struct BumpEvalContext {
     int faceIndex = 0;
 };
 
-// Bump-mapping Function Definitions
+// Normal Mapping Function Definitions
+inline PBRT_CPU_GPU void NormalMap(const Image *normalMap,
+                                   const NormalBumpEvalContext &ctx, Vector3f *dpdu,
+                                   Vector3f *dpdv) {
+    // Get normalized normal vector from normal map
+    WrapMode2D wrap(WrapMode::Repeat);
+    Point2f uv(ctx.uv[0], 1 - ctx.uv[1]);
+    Vector3f ns(2 * normalMap->BilerpChannel(uv, 0, wrap) - 1,
+                2 * normalMap->BilerpChannel(uv, 1, wrap) - 1,
+                2 * normalMap->BilerpChannel(uv, 2, wrap) - 1);
+    ns = Normalize(ns);
+
+    // Transform tangent-space normal to rendering space
+    Frame frame = Frame::FromZ(ctx.shading.n);
+    ns = frame.FromLocal(ns);
+
+    // Find $\dpdu$ and $\dpdv$ that give shading normal
+    Float ulen = Length(ctx.shading.dpdu), vlen = Length(ctx.shading.dpdv);
+    *dpdu = Normalize(GramSchmidt(ctx.shading.dpdu, ns)) * ulen;
+    *dpdv = Normalize(Cross(ns, *dpdu)) * vlen;
+}
+
+// Bump Mapping Function Definitions
 template <typename TextureEvaluator>
-PBRT_CPU_GPU void Bump(TextureEvaluator texEval, FloatTexture displacement,
-                       const Image *normalMap, const BumpEvalContext &ctx, Vector3f *dpdu,
-                       Vector3f *dpdv) {
-    DCHECK(displacement || normalMap);
-    if (displacement) {
-        if (displacement)
-            DCHECK(texEval.CanEvaluate({displacement}, {}));
-        // Compute offset positions and evaluate displacement texture
-        TextureEvalContext shiftedCtx = ctx;
-        // Shift _shiftedCtx_ _du_ in the $u$ direction
-        Float du = .5f * (std::abs(ctx.dudx) + std::abs(ctx.dudy));
-        if (du == 0)
-            du = .0005f;
-        shiftedCtx.p = ctx.p + du * ctx.shading.dpdu;
-        shiftedCtx.uv = ctx.uv + Vector2f(du, 0.f);
-
-        Float uDisplace = texEval(displacement, shiftedCtx);
-        // Shift _shiftedCtx_ _dv_ in the $v$ direction
-        Float dv = .5f * (std::abs(ctx.dvdx) + std::abs(ctx.dvdy));
-        if (dv == 0)
-            dv = .0005f;
-        shiftedCtx.p = ctx.p + dv * ctx.shading.dpdv;
-        shiftedCtx.uv = ctx.uv + Vector2f(0.f, dv);
-
-        Float vDisplace = texEval(displacement, shiftedCtx);
-        Float displace = texEval(displacement, ctx);
-
-        // Compute bump-mapped differential geometry
-        *dpdu = ctx.shading.dpdu + (uDisplace - displace) / du * Vector3f(ctx.shading.n) +
-                displace * Vector3f(ctx.shading.dndu);
-        *dpdv = ctx.shading.dpdv + (vDisplace - displace) / dv * Vector3f(ctx.shading.n) +
-                displace * Vector3f(ctx.shading.dndv);
-
-    } else {
-        // Sample normal map to compute shading normal
-        WrapMode2D wrap(WrapMode::Repeat);
-        Point2f uv(ctx.uv[0], 1 - ctx.uv[1]);
-        Vector3f ns(2 * normalMap->BilerpChannel(uv, 0, wrap) - 1,
-                    2 * normalMap->BilerpChannel(uv, 1, wrap) - 1,
-                    2 * normalMap->BilerpChannel(uv, 2, wrap) - 1);
-        ns = Normalize(ns);
-        Frame frame = Frame::FromZ(ctx.shading.n);
-        ns = frame.FromLocal(ns);
-
-        Float ulen = Length(ctx.shading.dpdu), vlen = Length(ctx.shading.dpdv);
-        *dpdu = Normalize(GramSchmidt(ctx.shading.dpdu, ns)) * ulen;
-        *dpdv = Normalize(Cross(ns, *dpdu)) * vlen;
-    }
+PBRT_CPU_GPU void BumpMap(TextureEvaluator texEval, FloatTexture displacement,
+                          const NormalBumpEvalContext &ctx, Vector3f *dpdu,
+                          Vector3f *dpdv) {
+    DCHECK(texEval.CanEvaluate({displacement}, {}));
+    // Compute offset positions and evaluate displacement texture
+    TextureEvalContext shiftedCtx = ctx;
+    // Shift _shiftedCtx_ _du_ in the $u$ direction
+    Float du = .5f * (std::abs(ctx.dudx) + std::abs(ctx.dudy));
+    if (du == 0)
+        du = .0005f;
+    shiftedCtx.p = ctx.p + du * ctx.shading.dpdu;
+    shiftedCtx.uv = ctx.uv + Vector2f(du, 0.f);
+
+    Float uDisplace = texEval(displacement, shiftedCtx);
+    // Shift _shiftedCtx_ _dv_ in the $v$ direction
+    Float dv = .5f * (std::abs(ctx.dvdx) + std::abs(ctx.dvdy));
+    if (dv == 0)
+        dv = .0005f;
+    shiftedCtx.p = ctx.p + dv * ctx.shading.dpdv;
+    shiftedCtx.uv = ctx.uv + Vector2f(0.f, dv);
+
+    Float vDisplace = texEval(displacement, shiftedCtx);
+    Float displace = texEval(displacement, ctx);
+
+    // Compute bump-mapped differential geometry
+    *dpdu = ctx.shading.dpdu + (uDisplace - displace) / du * Vector3f(ctx.shading.n) +
+            displace * Vector3f(ctx.shading.dndu);
+    *dpdv = ctx.shading.dpdv + (vDisplace - displace) / dv * Vector3f(ctx.shading.n) +
+            displace * Vector3f(ctx.shading.dndv);
 }
 
 // DielectricMaterial Definition
@@ -182,6 +185,8 @@ class DielectricMaterial {
         Float sampledEta = eta(lambda[0]);
         if (!eta.template Is<ConstantSpectrum>())
             lambda.TerminateSecondary();
+        // Handle edge case in case lambda[0] is beyond the wavelengths stored by the
+        // Spectrum.
         if (sampledEta == 0)
             sampledEta = 1;
 
@@ -203,8 +208,8 @@ class DielectricMaterial {
     FloatTexture displacement;
     Image *normalMap;
     FloatTexture uRoughness, vRoughness;
-    Spectrum eta;
     bool remapRoughness;
+    Spectrum eta;
 };
 
 // ThinDielectricMaterial Definition
@@ -226,6 +231,8 @@ class ThinDielectricMaterial {
         Float sampledEta = eta(lambda[0]);
         if (!eta.template Is<ConstantSpectrum>())
             lambda.TerminateSecondary();
+        // Handle edge case in case lambda[0] is beyond the wavelengths stored by the
+        // Spectrum.
         if (sampledEta == 0)
             sampledEta = 1;
 
@@ -276,6 +283,18 @@ class MixMaterial {
         materials[1] = m[1];
     }
 
+    template <typename TextureEvaluator>
+    PBRT_CPU_GPU Material ChooseMaterial(TextureEvaluator texEval,
+                                         MaterialEvalContext ctx) const {
+        Float amt = texEval(amount, ctx);
+        if (amt <= 0)
+            return materials[0];
+        if (amt >= 1)
+            return materials[1];
+        Float u = HashFloat(ctx.p, ctx.wo, materials[0], materials[1]);
+        return (amt < u) ? materials[0] : materials[1];
+    }
+
     PBRT_CPU_GPU
     Material GetMaterial(int i) const { return materials[i]; }
 
@@ -318,19 +337,6 @@ class MixMaterial {
         return texEval.CanEvaluate({amount}, {});
     }
 
-    template <typename TextureEvaluator>
-    PBRT_CPU_GPU Material ChooseMaterial(TextureEvaluator texEval,
-                                         MaterialEvalContext ctx) const {
-        Float amt = texEval(amount, ctx);
-        if (amt <= 0)
-            return materials[0];
-        if (amt >= 1)
-            return materials[1];
-
-        Float u = HashFloat(ctx.p, ctx.wo, materials[0], materials[1]);
-        return (amt < u) ? materials[0] : materials[1];
-    }
-
     template <typename TextureEvaluator>
     PBRT_CPU_GPU BSDF GetBSDF(TextureEvaluator texEval, MaterialEvalContext ctx,
                               SampledWavelengths &lambda, void *bxdf) const {

src/pbrt/wavefront/surfscatter.cpp

@@ -99,13 +99,23 @@ void WavefrontPathIntegrator::EvaluateMaterialAndBSDF(MaterialEvalQueue *evalQue
             Vector3f dpdus = w.dpdus;
             FloatTexture displacement = w.material->GetDisplacement();
             const Image *normalMap = w.material->GetNormalMap();
-            if (displacement || normalMap) {
-                // Call _Bump()_ to find shading geometry
+            if (normalMap) {
+                // Call _NormalMap()_ to find shading geometry
+                NormalBumpEvalContext bctx =
+                    w.GetNormalBumpEvalContext(dudx, dudy, dvdx, dvdy);
+                Vector3f dpdvs;
+                NormalMap(normalMap, bctx, &dpdus, &dpdvs);
+                ns = Normal3f(Normalize(Cross(dpdus, dpdvs)));
+                ns = FaceForward(ns, w.n);
+
+            } else if (displacement) {
+                // Call _BumpMap()_ to find shading geometry
                 if (displacement)
                     DCHECK(texEval.CanEvaluate({displacement}, {}));
-                BumpEvalContext bctx = w.GetBumpEvalContext(dudx, dudy, dvdx, dvdy);
+                NormalBumpEvalContext bctx =
+                    w.GetNormalBumpEvalContext(dudx, dudy, dvdx, dvdy);
                 Vector3f dpdvs;
-                Bump(texEval, displacement, normalMap, bctx, &dpdus, &dpdvs);
+                BumpMap(texEval, displacement, bctx, &dpdus, &dpdvs);
                 ns = Normal3f(Normalize(Cross(dpdus, dpdvs)));
                 ns = FaceForward(ns, w.n);
             }

src/pbrt/wavefront/workitems.h

@@ -280,9 +280,9 @@ template <typename ConcreteMaterial>
 struct MaterialEvalWorkItem {
     // MaterialEvalWorkItem Public Methods
     PBRT_CPU_GPU
-    BumpEvalContext GetBumpEvalContext(Float dudx, Float dudy, Float dvdx,
-                                       Float dvdy) const {
-        BumpEvalContext ctx;
+    NormalBumpEvalContext GetNormalBumpEvalContext(Float dudx, Float dudy, Float dvdx,
+                                                   Float dvdy) const {
+        NormalBumpEvalContext ctx;
         ctx.p = Point3f(pi);
         ctx.uv = uv;
         ctx.dudx = dudx;