diff --git a/src/game/systems/painting-system.cpp b/src/game/systems/painting-system.cpp
index cc07ac1..de64691 100644
--- a/src/game/systems/painting-system.cpp
+++ b/src/game/systems/painting-system.cpp
@@ -180,8 +180,7 @@ void painting_system::update(double t, double dt)
 				
 				/// @TODO: smooth normals in middle of segment
 				
-				float3 tangents[12];
-				float3 bitangents[12];
+				float4 tangents[12];
 				for (int i = 0; i < 4; ++i)
 				{
 					const float3& a = tangent_positions[i * 3];
@@ -204,13 +203,12 @@ void painting_system::update(double t, double dt)
 					tangent = math::normalize(tangent_rotation * tangent);
 					bitangent = math::normalize(tangent_rotation * bitangent);
 					
-					tangents[i * 3] = tangent;
-					tangents[i * 3 + 1] = tangent;
-					tangents[i * 3 + 2] = tangent;
+					// Calculate sign of bitangent
+					float bitangent_sign = (math::dot(math::cross(surface_normal, tangent), bitangent) < 0.0f) ? -1.0f : 1.0f;
 					
-					bitangents[i * 3] = bitangent;
-					bitangents[i * 3 + 1] = bitangent;
-					bitangents[i * 3 + 2] = bitangent;
+					tangents[i * 3] = {tangent.x, tangent.y, tangent.z, bitangent_sign};
+					tangents[i * 3 + 1] = {tangent.x, tangent.y, tangent.z, bitangent_sign};
+					tangents[i * 3 + 2] = {tangent.x, tangent.y, tangent.z, bitangent_sign};
 				}
 				
 				float vertex_data[13 * 12];
@@ -232,7 +230,7 @@ void painting_system::update(double t, double dt)
 					*(v++) = tangents[i].x;
 					*(v++) = tangents[i].y;
 					*(v++) = tangents[i].z;
-					*(v++) = 0.0f;
+					*(v++) = tangents[i].w;
 				}
 				
 				std::size_t segment_size = sizeof(float) * vertex_size * 6;
diff --git a/src/resources/model-loader.cpp b/src/resources/model-loader.cpp
index 87529ed..d3427a2 100644
--- a/src/resources/model-loader.cpp
+++ b/src/resources/model-loader.cpp
@@ -356,13 +356,6 @@ model* resource_loader<model>::load(resource_manager* resource_manager, PHYSFS_F
 }
 */
 
-static struct attribute_data
-{
-	std::string type;
-	std::size_t size;
-	std::vector<float> data;
-};
-
 template <>
 model* resource_loader<model>::load(resource_manager* resource_manager, PHYSFS_File* file)
 {
@@ -519,8 +512,6 @@ model* resource_loader<model>::load(resource_manager* resource_manager, PHYSFS_F
 			if (auto size_node = material_node.value().find("size"); size_node != material_node.value().end())
 				group_size = size_node.value().get<std::size_t>();
 			
-			std::cout << "MATERIAL: " << group_name << std::endl;
-			
 			group_material = resource_manager->load<material>(group_name + ".mtl");
 			
 			model_group* model_group = model->add_group(group_name);