make intersection routines more robust vs NaNs

src/emitters/constant.cpp

@@ -196,7 +196,7 @@ public:
 		if (!m_sceneBSphere.rayIntersect(ray, nearT, farT))
 			return Spectrum(0.0f);
 
-		if (nearT >= 0 || farT <= 0)
+		if (!(nearT < 0 && farT > 0))
 			return Spectrum(0.0f);
 
 		dRec.p = ray(farT);

src/shapes/cylinder.cpp

@@ -145,11 +145,12 @@ public:
 		if (!solveQuadratic(A, B, C, nearT, farT))
 			return false;
 
-		if (nearT > maxt || farT < mint)
+		if (!(nearT <= maxt && farT >= mint)) /* NaN-aware conditionals */
 			return false;
 
 		const Float zPosNear = ray.o.z + ray.d.z * nearT;
 		const Float zPosFar = ray.o.z + ray.d.z * farT;
+
 		if (zPosNear >= 0 && zPosNear <= m_length && nearT >= mint) {
 			t = nearT;
 		} else if (zPosFar >= 0 && zPosFar <= m_length) {

src/shapes/disk.cpp

@@ -136,7 +136,7 @@ public:
 		m_worldToObject.transformAffine(_ray, ray);
 		Float hit = -ray.o.z / ray.d.z;
 
-		if (hit < mint || hit > maxt)
+		if (!(hit >= mint && hit <= maxt))
 			return false;
 
 		Point local = ray(hit);

src/shapes/hair.cpp

@@ -504,7 +504,7 @@ public:
 		if (!solveQuadraticDouble(A, B, C, nearT, farT))
 			return false;
 
-		if (nearT > maxt || farT < mint)
+		if (!(nearT <= maxt && farT >= mint)) /* NaN-aware conditionals */
 			return false;
 
 		/* Next check the intersection points against the miter planes */
@@ -523,7 +523,7 @@ public:
 			p = Point(rayO + rayD * nearT);
 			t = (Float) nearT;
 		} else if (dot(pointFar - v1, n1) >= 0 &&
-				dot(pointFar - v2, n2) <= 0) {
+		           dot(pointFar - v2, n2) <= 0) {
 			if (farT > maxt)
 				return false;
 			p = Point(rayO + rayD * nearT);

src/shapes/rectangle.cpp

@@ -127,7 +127,7 @@ public:
 		m_worldToObject.transformAffine(_ray, ray);
 		Float hit = -ray.o.z / ray.d.z;
 
-		if (hit < mint || hit > maxt)
+		if (!(hit >= mint && hit <= maxt))
 			return false;
 
 		Point local = ray(hit);

src/shapes/sphere.cpp

@@ -172,8 +172,9 @@ public:
 		if (!solveQuadraticDouble(A, B, C, nearT, farT))
 			return false;
 
-		if (nearT > maxt || farT < mint)
+		if (!(nearT <= maxt && farT >= mint)) /* NaN-aware conditionals */
 			return false;
+
 		if (nearT < mint) {
 			if (farT > maxt)
 				return false;