extended the chi2-tester with some extra checks for BSDF::pdf() and BSDF::eval()

data/tests/test_bsdf.xml

@@ -2,22 +2,6 @@
 	 to be tested for consistency. This is done
 	 using the testcase 'test_chisquare' -->
 <scene>
-	<!-- Test the rough dielectric model with the anisotropic
-		 Ashikhmin-Shirley microfacet distribution -->
-	<bsdf type="roughdielectric">
-		<string name="distribution" value="as"/>
-		<float name="alphaU" value=".1"/>
-		<float name="alphaV" value=".3"/>
-		<float name="intIOR" value="1.5"/>
-		<float name="extIOR" value="1.0"/>
-	</bsdf>
-
-	<!-- Test the dielectric model -->
-	<bsdf type="dielectric">
-		<string name="intIOR" value="water"/>
-		<string name="extIOR" value="air"/>
-	</bsdf>
-
 	<!-- Test the diffuse model -->
 	<bsdf type="diffuse"/>
 
@@ -40,6 +24,27 @@
 	<!-- Test the conductor model -->
 	<bsdf type="conductor"/>
 
+	<!-- Test the dielectric model -->
+	<bsdf type="dielectric">
+		<string name="intIOR" value="water"/>
+		<string name="extIOR" value="air"/>
+	</bsdf>
+
+	<!-- Test a mixture of degenerate materials -->
+	<bsdf type="mixture">
+		<string name="weights" value=".8 .2"/>
+		<bsdf type="dielectric"/>
+		<bsdf type="conductor"/>
+	</bsdf>
+	
+	<!-- Test a mixture of degenerate and
+		 non-degenerate materials -->
+	<bsdf type="mixture">
+		<string name="weights" value=".8 .2"/>
+		<bsdf type="dielectric"/>
+		<bsdf type="diffuse"/>
+	</bsdf>
+
 	<!-- Test the rough glass model with the 
 		 Beckmann microfacet distribution -->
 	<bsdf type="roughdielectric">

src/bsdfs/conductor.cpp

@@ -265,6 +265,7 @@ public:
 	std::string toString() const {
 		std::ostringstream oss;
 		oss << "SmoothConductor[" << endl
+			<< "  name = \"" << getName() << "\"," << endl
 			<< "  eta = " << m_eta.toString() << "," << endl
 			<< "  k = " << m_k.toString() << "," << endl
 			<< "  specularReflectance = " << indent(m_specularReflectance->toString()) << endl

src/bsdfs/dielectric.cpp

@@ -477,6 +477,7 @@ public:
 	std::string toString() const {
 		std::ostringstream oss;
 		oss << "SmoothDielectric[" << endl
+			<< "  name = \"" << getName() << "\"," << endl
 			<< "  intIOR = " << m_intIOR << "," << endl 
 			<< "  extIOR = " << m_extIOR << "," << endl
 			<< "  specularReflectance = " << indent(m_specularReflectance->toString()) << "," << endl

src/bsdfs/difftrans.cpp

@@ -129,6 +129,7 @@ public:
 	std::string toString() const {
 		std::ostringstream oss;
 		oss << "DiffuseTransmitter[" << endl
+			<< "  name = \"" << getName() << "\"," << endl
 			<< "  transmittance = " << indent(m_transmittance->toString()) << endl
 			<< "]";
 		return oss.str();

src/bsdfs/mixture.cpp

@@ -37,7 +37,6 @@ public:
 			Log(EError, "No weights were supplied!");
 		m_weights.resize(weights.size());
 
-		Float totalWeight = 0;
 		char *end_ptr = NULL;
 		for (size_t i=0; i<weights.size(); ++i) {
 			Float weight = (Float) strtod(weights[i].c_str(), &end_ptr);
@@ -46,13 +45,7 @@ public:
 			if (weight < 0)
 				SLog(EError, "Invalid BRDF weight!");
 			m_weights[i] = weight;
-			totalWeight += weight;
 		}
-
-		if (totalWeight > 1)
-			Log(EWarn, "Energy conservation is violated!");
-		if (totalWeight == 0)
-			Log(EError, "Combined weight must be > 0!");
 	}
 
 	MixtureBSDF(Stream *stream, InstanceManager *manager) 
@@ -91,6 +84,27 @@ public:
 			Log(EError, "BSDF count mismatch: " SIZE_T_FMT " bsdfs, but specified " SIZE_T_FMT " weights",
 				m_bsdfs.size(), m_bsdfs.size());
 
+		Float totalWeight = 0;
+		for (size_t i=0; i<m_weights.size(); ++i)
+			totalWeight += m_weights[i];
+
+		if (totalWeight <= 0)
+			Log(EError, "The weights must sum to a value greater than zero!");
+
+		if (m_ensureEnergyConservation && totalWeight > 1) {
+			std::ostringstream oss;
+			Float scale = 1.0f / totalWeight;
+			oss << "The BSDF" << endl << toString() << endl
+				<< "potentially violates energy conservation, since the weights "
+				<< "sum to " << totalWeight << ", which is greater than one! "
+				<< "They will be re-scaled to avoid potential issues. Specify "
+				<< "the parameter ensureEnergyConservation=false to prevent "
+				<< "this from happening.";
+			Log(EWarn, "%s", oss.str().c_str());
+			for (size_t i=0; i<m_weights.size(); ++i)
+				m_weights[i] *= scale;
+		}
+
 		for (size_t i=0; i<m_bsdfs.size(); ++i)
 			componentCount += m_bsdfs[i]->getComponentCount();
 
@@ -239,6 +253,7 @@ public:
 	std::string toString() const {
 		std::ostringstream oss;
 		oss << "MixtureBSDF[" << endl
+			<< "  name = \"" << getName() << "\"," << endl
 			<< "  weights = {";
 		for (size_t i=0; i<m_bsdfs.size(); ++i) {
 			oss << " " << m_weights[i];

src/librender/bsdf.cpp

@@ -90,24 +90,26 @@ Texture *BSDF::ensureEnergyConservation(Texture *texture,
 static std::string typeMaskToString(unsigned int typeMask) {
 	std::ostringstream oss;
 	oss << "{ ";
-	if (typeMask & BSDF::EAll) { oss << "all "; typeMask &= ~BSDF::EAll; }
+	#define isset(mask) (typeMask & mask) == mask
-	if (typeMask & BSDF::ESmooth) { oss << "smooth "; typeMask &= ~BSDF::ESmooth; }
+	if (isset(BSDF::EAll)) { oss << "all "; typeMask &= ~BSDF::EAll; }
-	if (typeMask & BSDF::EDiffuse) { oss << "diffuse "; typeMask &= ~BSDF::EDiffuse; }
+	if (isset(BSDF::ESmooth)) { oss << "smooth "; typeMask &= ~BSDF::ESmooth; }
-	if (typeMask & BSDF::EGlossy) { oss << "glossy "; typeMask &= ~BSDF::EGlossy; }
+	if (isset(BSDF::EDiffuse)) { oss << "diffuse "; typeMask &= ~BSDF::EDiffuse; }
-	if (typeMask & BSDF::EDelta) { oss << "delta"; typeMask &= ~BSDF::EDelta; }
+	if (isset(BSDF::EGlossy)) { oss << "glossy "; typeMask &= ~BSDF::EGlossy; }
-	if (typeMask & BSDF::EDelta1D) { oss << "delta1D "; typeMask &= ~BSDF::EDelta1D; }
+	if (isset(BSDF::EDelta)) { oss << "delta"; typeMask &= ~BSDF::EDelta; }
-	if (typeMask & BSDF::EDiffuseReflection) { oss << "diffuseReflection "; typeMask &= ~BSDF::EDiffuseReflection; }
+	if (isset(BSDF::EDelta1D)) { oss << "delta1D "; typeMask &= ~BSDF::EDelta1D; }
-	if (typeMask & BSDF::EDiffuseTransmission) { oss << "diffuseTransmission "; typeMask &= ~BSDF::EDiffuseTransmission; }
+	if (isset(BSDF::EDiffuseReflection)) { oss << "diffuseReflection "; typeMask &= ~BSDF::EDiffuseReflection; }
-	if (typeMask & BSDF::EGlossyReflection) { oss << "glossyReflection "; typeMask &= ~BSDF::EGlossyReflection; }
+	if (isset(BSDF::EDiffuseTransmission)) { oss << "diffuseTransmission "; typeMask &= ~BSDF::EDiffuseTransmission; }
-	if (typeMask & BSDF::EGlossyTransmission) { oss << "glossyTransmission "; typeMask &= ~BSDF::EGlossyTransmission; }
+	if (isset(BSDF::EGlossyReflection)) { oss << "glossyReflection "; typeMask &= ~BSDF::EGlossyReflection; }
-	if (typeMask & BSDF::EDeltaReflection) { oss << "deltaReflection "; typeMask &= ~BSDF::EDeltaReflection; }
+	if (isset(BSDF::EGlossyTransmission)) { oss << "glossyTransmission "; typeMask &= ~BSDF::EGlossyTransmission; }
-	if (typeMask & BSDF::EDeltaTransmission) { oss << "deltaTransmission "; typeMask &= ~BSDF::EDeltaTransmission; }
+	if (isset(BSDF::EDeltaReflection)) { oss << "deltaReflection "; typeMask &= ~BSDF::EDeltaReflection; }
-	if (typeMask & BSDF::EDelta1DReflection) { oss << "delta1DReflection "; typeMask &= ~BSDF::EDelta1DReflection; }
+	if (isset(BSDF::EDeltaTransmission)) { oss << "deltaTransmission "; typeMask &= ~BSDF::EDeltaTransmission; }
-	if (typeMask & BSDF::EDelta1DTransmission) { oss << "delta1DTransmission "; typeMask &= ~BSDF::EDelta1DTransmission; }
+	if (isset(BSDF::EDelta1DReflection)) { oss << "delta1DReflection "; typeMask &= ~BSDF::EDelta1DReflection; }
-	if (typeMask & BSDF::EAnisotropic) { oss << "anisotropic "; typeMask &= ~BSDF::EAnisotropic; }
+	if (isset(BSDF::EDelta1DTransmission)) { oss << "delta1DTransmission "; typeMask &= ~BSDF::EDelta1DTransmission; }
-	if (typeMask & BSDF::EFrontSide) { oss << "frontSide "; typeMask &= ~BSDF::EFrontSide; }
+	if (isset(BSDF::EAnisotropic)) { oss << "anisotropic "; typeMask &= ~BSDF::EAnisotropic; }
-	if (typeMask & BSDF::EBackSide) { oss << "backSide "; typeMask &= ~BSDF::EBackSide; }
+	if (isset(BSDF::EFrontSide)) { oss << "frontSide "; typeMask &= ~BSDF::EFrontSide; }
-	if (typeMask & BSDF::ECanUseSampler) { oss << "canUseSampler "; typeMask &= ~BSDF::ECanUseSampler; }
+	if (isset(BSDF::EBackSide)) { oss << "backSide "; typeMask &= ~BSDF::EBackSide; }
+	if (isset(BSDF::ECanUseSampler)) { oss << "canUseSampler "; typeMask &= ~BSDF::ECanUseSampler; }
+	#undef isset
 	oss << "}";
 	return oss.str();
 }

src/tests/test_chisquare.cpp

@@ -112,7 +112,7 @@ public:
 				enableFPExceptions();
 			#endif
 	
-			Float pdfVal;
+			Float pdfVal, pdfVal2;
 	
 			/* Only make the sampler available to the BSDF when requested
 			   by the testcase. This allows testing both sampling variants
@@ -123,42 +123,48 @@ public:
 			if (m_passSamplerToBSDF)
 				bRec.sampler = m_fakeSampler;
 
-			/* Check the various sampling routines for agreement amongst each other */
+			/* Check the various sampling routines for agreement 
+			   amongst each other */
 			m_fakeSampler->clear();
 			Spectrum f = m_bsdf->sample(bRec, pdfVal, sample);
 			m_fakeSampler->rewind();
 			Spectrum sampled = m_bsdf->sample(bRec, sample);
+			EMeasure measure = ESolidAngle;
+			if (!f.isZero())
+				measure = BSDF::getMeasure(bRec.sampledType);
+			Spectrum f2 = m_bsdf->eval(bRec, measure);
+			pdfVal2 = m_bsdf->pdf(bRec, measure);
 
-			if (f.isZero() || pdfVal == 0) {
+			if (f.isZero() || pdfVal == 0 || pdfVal2 == 0) {
-				if (!sampled.isZero()) 
+				if (!sampled.isZero())
-					Log(EWarn, "Inconsistency (1): f=%s, pdf=%f, sampled f/pdf=%s, bRec=%s",
+					Log(EWarn, "Inconsistency (1): f=%s, f2=%s, pdf=%f, pdf2=%f, sampled f/pdf=%s, bRec=%s, measure=%i",
-						f.toString().c_str(), pdfVal, sampled.toString().c_str(), bRec.toString().c_str());
+						f.toString().c_str(), f2.toString().c_str(), pdfVal, pdfVal2, sampled.toString().c_str(), bRec.toString().c_str(), measure);
 				#if defined(MTS_DEBUG_FP)
 					disableFPExceptions();
 				#endif
 				return boost::make_tuple(bRec.wo, 0.0f, ESolidAngle);
 			} else if (sampled.isZero()) {
-				if (!f.isZero() && pdfVal != 0)
+				if ((!f.isZero() && pdfVal != 0) || (!f2.isZero() && pdfVal2 != 0))
-					Log(EWarn, "Inconsistency (2): f=%s, pdf=%f, sampled f/pdf=%s, bRec=%s",
+					Log(EWarn, "Inconsistency (2): f=%s, f2=%s, pdf=%f, pdf2=%f, sampled f/pdf=%s, bRec=%s, measure=%i",
-						f.toString().c_str(), pdfVal, sampled.toString().c_str(), bRec.toString().c_str());
+						f.toString().c_str(), f2.toString().c_str(), pdfVal, pdfVal2, sampled.toString().c_str(), bRec.toString().c_str(), measure);
 				#if defined(MTS_DEBUG_FP)
 					disableFPExceptions();
 				#endif
 				return boost::make_tuple(bRec.wo, 0.0f, ESolidAngle);
 			}
 
-			Spectrum sampled2 = f/pdfVal;
+			Spectrum sampled2 = f/pdfVal, evaluated = f2/pdfVal2;
-			if (!sampled.isValid() || !sampled2.isValid()) {
+			if (!sampled.isValid() || !sampled2.isValid() || !evaluated.isValid()) {
-				Log(EWarn, "Ooops: f=%s, pdf=%f, sampled f/pdf=%s, bRec=%s",
+				Log(EWarn, "Ooops: f=%s, f2=%s, pdf=%f, pdf2=%f, sampled f/pdf=%s, bRec=%s, measure=%i",
-					f.toString().c_str(), pdfVal, sampled.toString().c_str(), bRec.toString().c_str());
+					f.toString().c_str(), f2.toString().c_str(), pdfVal, pdfVal2, sampled.toString().c_str(), bRec.toString().c_str(), measure);
 				return boost::make_tuple(bRec.wo, 0.0f, ESolidAngle);
 			}
 
 			bool mismatch = false;
 			for (int i=0; i<SPECTRUM_SAMPLES; ++i) {
-				Float a = sampled[i], b = sampled2[i];
+				Float a = sampled[i], b = sampled2[i], c = evaluated[i];
-				Float min = std::min(a, b);
+				Float min = std::min(std::min(a, b), c);
-				Float err = std::abs(a - b);
+				Float err = std::max(std::max(std::abs(a - b), std::abs(a - c)), std::abs(b - c));
 				m_largestWeight = std::max(m_largestWeight, a);
 
 				if (min < ERROR_REQ && err > ERROR_REQ) // absolute error threshold
@@ -168,15 +174,14 @@ public:
 			}
 
 			if (mismatch)
-				Log(EWarn, "Potential inconsistency (3): f/pdf=%s, sampled f/pdf=%s",
+				Log(EWarn, "Potential inconsistency (3): f/pdf=%s (method 1), f/pdf=%s (methdod 2), sampled f/pdf=%s",
-					sampled2.toString().c_str(), sampled.toString().c_str());
+					sampled2.toString().c_str(), evaluated.toString().c_str(), sampled.toString().c_str());
-			
+
 			#if defined(MTS_DEBUG_FP)
 				disableFPExceptions();
 			#endif
 
-			return boost::make_tuple(bRec.wo, 1.0f, 
+			return boost::make_tuple(bRec.wo, 1.0f, measure);
-				BSDF::getMeasure(bRec.sampledType));
 		}
  
 		Float pdf(const Vector &wo, EMeasure measure) {