From 1fd0f671dfcb77f813c0d6a36f2aa4e480b5ca8e Mon Sep 17 00:00:00 2001
From: Girish Ramesh <rgirish28@gmail.com>
Date: Wed, 2 May 2018 14:00:42 +0100
Subject: [PATCH] Fixed partial derivative NaN error for hair (#60)

---
 src/shapes/hair.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/shapes/hair.cpp b/src/shapes/hair.cpp
index 9106be9d..19a9c693 100644
--- a/src/shapes/hair.cpp
+++ b/src/shapes/hair.cpp
@@ -846,6 +846,7 @@ void HairShape::fillIntersectionRecord(const Ray &ray,
     its.p += its.geoFrame.n * (m_kdtree->getRadius() - std::sqrt(local.y*local.y+local.z*local.z));
 
     its.shFrame.n = its.geoFrame.n;
+    coordinateSystem(its.shFrame.n, its.dpdu, its.dpdv);
     its.hasUVPartials = false;
     its.instance = this;
     its.time = ray.time;