From c4045a10662127f2b322aaf47d6f56ebe198b2be Mon Sep 17 00:00:00 2001
From: Wenzel Jakob <wenzel@cs.cornell.edu>
Date: Thu, 31 Jan 2013 21:19:28 -0500
Subject: [PATCH] further restricted roughness range to prevent numerical
 overflow issues on single precision

---
 src/bsdfs/microfacet.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/bsdfs/microfacet.h b/src/bsdfs/microfacet.h
index 16799e97..9fbf7538 100644
--- a/src/bsdfs/microfacet.h
+++ b/src/bsdfs/microfacet.h
@@ -84,7 +84,11 @@ public:
 	 * (For lower roughness values, please switch to the smooth BSDF variants)
 	 */
 	Float transformRoughness(Float value) const {
-		value = std::max(value, (Float) 1e-5f);
+		#if defined(SINGLE_PRECISION)
+			value = std::max(value, (Float) 1e-3f);
+		#else
+			value = std::max(value, (Float) 1e-5f);
+		#endif
 		if (m_type == EPhong || m_type == EAshikhminShirley)
 			value = std::max(2 / (value * value) - 2, (Float) 0.1f);
 		return value;