From e1ff84e0a984a89894f2c238014c91399fb14a98 Mon Sep 17 00:00:00 2001
From: Wenzel Jakob <wenzel@cs.cornell.edu>
Date: Fri, 12 Oct 2012 18:25:22 -0400
Subject: [PATCH] minor robustness improvements

---
 src/libbidir/mut_manifold.cpp |  2 ++
 src/librender/skdtree.cpp     |  5 +++++
 src/shapes/disk.cpp           | 23 ++++++++++++-----------
 src/shapes/rectangle.cpp      | 19 ++++++++++---------
 4 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/src/libbidir/mut_manifold.cpp b/src/libbidir/mut_manifold.cpp
index 36baf6a4..9fdc9493 100644
--- a/src/libbidir/mut_manifold.cpp
+++ b/src/libbidir/mut_manifold.cpp
@@ -669,6 +669,8 @@ Float ManifoldPerturbation::Q(const Path &source, const Path &proposal,
 			source.vertex(a)->pdf[mode] * m_probFactor * m_probFactor);
 
 		Float pdf = source.vertex(a+step)->perturbPositionPdf(proposal.vertex(a+step), stddev);
+		if (pdf == 0)
+			return 0.0f;
 
 		weight /= pdf;
 	}
diff --git a/src/librender/skdtree.cpp b/src/librender/skdtree.cpp
index 236b72c0..83fad551 100644
--- a/src/librender/skdtree.cpp
+++ b/src/librender/skdtree.cpp
@@ -128,6 +128,11 @@ bool ShapeKDTree::rayIntersect(const Ray &ray, Intersection &its) const {
 		if (EXPECT_TAKEN(maxt > mint)) {
 			if (rayIntersectHavran<false>(ray, mint, maxt, its.t, temp)) {
 				fillIntersectionRecord<true>(ray, temp, its);
+				if (std::isnan(its.t)) {
+					cout << ray.toString() << endl;
+					cout << its.toString() << endl;
+					Log(EError, "Whaat?!");
+				}
 				return true;
 			}
 		}
diff --git a/src/shapes/disk.cpp b/src/shapes/disk.cpp
index 343ea8db..35c74894 100644
--- a/src/shapes/disk.cpp
+++ b/src/shapes/disk.cpp
@@ -134,25 +134,26 @@ public:
 	inline bool rayIntersect(const Ray &_ray, Float mint, Float maxt, Float &t, void *temp) const {
 		Ray ray;
 		m_worldToObject.transformAffine(_ray, ray);
-		Float hit = -ray.o.z/ray.d.z;
+		Float hit = -ray.o.z / ray.d.z;
 
 		if (hit < mint || hit > maxt)
 			return false;
 
 		Point local = ray(hit);
 
-		if (local.x * local.x + local.y * local.y > 1)
+		if (local.x * local.x + local.y * local.y <= 1) {
+			t = hit;
+
+			if (temp) {
+				Float *data = static_cast<Float *>(temp);
+				data[0] = local.x;
+				data[1] = local.y;
+			}
+
+			return true;
+		} else {
 			return false;
-
-		t = hit;
-
-		if (temp) {
-			Float *data = static_cast<Float *>(temp);
-			data[0] = local.x;
-			data[1] = local.y;
 		}
-
-		return true;
 	}
 
 	bool rayIntersect(const Ray &ray, Float mint, Float maxt) const {
diff --git a/src/shapes/rectangle.cpp b/src/shapes/rectangle.cpp
index c4055818..1389b5e5 100644
--- a/src/shapes/rectangle.cpp
+++ b/src/shapes/rectangle.cpp
@@ -125,25 +125,26 @@ public:
 	inline bool rayIntersect(const Ray &_ray, Float mint, Float maxt, Float &t, void *temp) const {
 		Ray ray;
 		m_worldToObject.transformAffine(_ray, ray);
-		Float hit = -ray.o.z/ray.d.z;
+		Float hit = -ray.o.z / ray.d.z;
 
 		if (hit < mint || hit > maxt)
 			return false;
 
 		Point local = ray(hit);
 
-		if (std::abs(local.x) > 1 || std::abs(local.y) > 1)
-			return false;
+		if (std::abs(local.x) <= 1 && std::abs(local.y) <= 1) {
+			t = hit;
 
-		t = hit;
+			if (temp) {
+				Float *data = static_cast<Float *>(temp);
+				data[0] = local.x;
+				data[1] = local.y;
+			}
 
-		if (temp) {
-			Float *data = static_cast<Float *>(temp);
-			data[0] = local.x;
-			data[1] = local.y;
+			return true;
 		}
 
-		return true;
+		return false;
 	}
 
 	bool rayIntersect(const Ray &ray, Float mint, Float maxt) const {