From e0c7aaf5adff1920b94dfd37dd1d5ab0ccc8c43a Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brechtvanlommel@gmail.com>
Date: Fri, 29 Jul 2016 02:22:01 +0200
Subject: Fix Cycles OSL hair BSDF inconsistencies with SVM.

---
 intern/cycles/kernel/shaders/node_hair_bsdf.osl | 45 +++++++++++++------------
 tests/python/cycles_render_tests.py             |  2 ++
 2 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/intern/cycles/kernel/shaders/node_hair_bsdf.osl b/intern/cycles/kernel/shaders/node_hair_bsdf.osl
index c8cb88f0c0b..ef8f2fae894 100644
--- a/intern/cycles/kernel/shaders/node_hair_bsdf.osl
+++ b/intern/cycles/kernel/shaders/node_hair_bsdf.osl
@@ -24,34 +24,35 @@ shader node_hair_bsdf(
 	float Offset = 0.0,
 	float RoughnessU = 0.1,
 	float RoughnessV = 1.0,
-	normal Normal = Ng,
+	normal Tangent = normal(0, 0, 0),
 	output closure color BSDF = 0)
 {
-	float IsStrand;
 	float roughnessh = clamp(RoughnessU, 0.001, 1.0);
 	float roughnessv = clamp(RoughnessV, 0.001, 1.0);
-	getattribute("geom:is_curve", IsStrand);
+	float offset = -Offset;
 
-	if (!IsStrand) {
-		if (backfacing()) {
-			BSDF = transparent();
-		}
-		else {
-			if (component == "reflection")
-				BSDF = Color * hair_reflection(Normal, roughnessh, roughnessv, normalize(dPdv), 0.0);
-			else
-				BSDF = Color * hair_transmission(Normal, roughnessh, roughnessv, normalize(dPdv), 0.0);
-		}
+	normal T;
+	float IsCurve = 0;
+	getattribute("geom:is_curve", IsCurve);
+
+	if (isconnected(Tangent)) {
+		T = Tangent;
+	}
+	else if(!IsCurve) {
+		T = normalize(dPdv);
+		offset = 0.0;
+	}
+	else {
+		T = normalize(dPdu);
+	}
+
+	if (backfacing() && IsCurve) {
+		BSDF = transparent();
 	}
 	else {
-		if (backfacing()) {
-			BSDF = transparent();
-		}
-		else {
-			if (component == "reflection")
-				BSDF = Color * hair_reflection(Normal, roughnessh, roughnessv, dPdu, -Offset);
-			else
-				BSDF = Color * hair_transmission(Normal, roughnessh, roughnessv, dPdu, -Offset);
-		}
+		if (component == "reflection")
+			BSDF = Color * hair_reflection(Ng, roughnessh, roughnessv, T, offset);
+		else
+			BSDF = Color * hair_transmission(Ng, roughnessh, roughnessv, T, offset);
 	}
 }
diff --git a/tests/python/cycles_render_tests.py b/tests/python/cycles_render_tests.py
index 1434447416d..fb9a4b348b7 100755
--- a/tests/python/cycles_render_tests.py
+++ b/tests/python/cycles_render_tests.py
@@ -17,6 +17,8 @@ def render_file(filepath):
         "--factory-startup",
         filepath,
         "-E", "CYCLES",
+        # Run with OSL enabled
+        # "--python-expr", "import bpy; bpy.context.scene.cycles.shading_system = True",
         "-o", TEMP_FILE_MASK,
         "-F", "PNG",
         "-f", "1",
-- 
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