Cycles: Anisotropic BSDF enabled, with tangents now computed from the active UV map.

It's using the Ward BSDF currently, which has some energy loss so might be a bit
dark. More/better BSDF options can be implemented later.

Patch by Mike Farnsworth, some modifications by me. Currently it's not possible yet
to set a custom tangent, that will follow as part of per-bsdf normals patch.

intern/cycles/blender/blender_mesh.cpp

@@ -33,6 +33,28 @@ CCL_NAMESPACE_BEGIN
 
 /* Find/Add */
 
+static float3 tri_calc_tangent(float3 v0, float3 v1, float3 v2, float3 tx0, float3 tx1, float3 tx2)
+{
+	float3 duv1 = tx2 - tx0;
+	float3 duv2 = tx2 - tx1;
+	float3 dp1 = v2 - v0;
+	float3 dp2 = v2 - v1;
+	float det = duv1[0] * duv2[1] - duv1[1] * duv2[0];
+
+	if(det != 0.0f) {
+		return normalize(dp1 * duv2[1] - dp2 * duv1[1]);
+	}
+	else {
+		/* give back a sane default, using a valid edge as a fallback */
+		float3 edge = v1 - v0;
+
+		if(len(edge) == 0.0f)
+			edge = v2 - v0;
+
+		return normalize(edge);
+	}
+}
+
 static void create_mesh(Scene *scene, Mesh *mesh, BL::Mesh b_mesh, const vector<uint>& used_shaders)
 {
 	/* create vertices */
@@ -157,6 +179,67 @@ static void create_mesh(Scene *scene, Mesh *mesh, BL::Mesh b_mesh, const vector<
 			}
 		}
 	}
+
+	/* create texcoord-based tangent attributes */
+	{
+		BL::Mesh::tessface_uv_textures_iterator l;
+
+		for(b_mesh.tessface_uv_textures.begin(l); l != b_mesh.tessface_uv_textures.end(); ++l) {
+			AttributeStandard std = (l->active_render())? ATTR_STD_TANGENT: ATTR_STD_NONE;
+
+			if(!mesh->need_attribute(scene, std))
+				continue;
+
+			Attribute *attr = mesh->attributes.add(std, ustring("Tangent"));
+
+			/* compute average tangents per vertex */
+			float3 *tangents = attr->data_float3();
+			memset(tangents, 0, sizeof(float3)*mesh->verts.size());
+
+			BL::MeshTextureFaceLayer::data_iterator t;
+
+			size_t fi = 0; /* face index */
+			b_mesh.tessfaces.begin(f);
+			for(l->data.begin(t); t != l->data.end() && f != b_mesh.tessfaces.end(); ++t, ++fi, ++f) {
+				int4 vi = get_int4(f->vertices_raw());
+
+				float3 tx0 = get_float3(t->uv1());
+				float3 tx1 = get_float3(t->uv2());
+				float3 tx2 = get_float3(t->uv3());
+
+				float3 v0 = mesh->verts[vi[0]];
+				float3 v1 = mesh->verts[vi[1]];
+				float3 v2 = mesh->verts[vi[2]];
+
+				/* calculate tangent for the triangle;
+				 * get vertex positions, and find change in position with respect
+				 * to the texture coords in the first texture coord dimension */
+				float3 tangent0 = tri_calc_tangent(v0, v1, v2, tx0, tx1, tx2);
+
+				if(nverts[fi] == 4) {
+					/* quad tangent */
+					float3 tx3 = get_float3(t->uv4());
+					float3 v3 = mesh->verts[vi[3]];
+					float3 tangent1 = tri_calc_tangent(v0, v2, v3, tx0, tx2, tx3);
+
+					tangents[vi[0]] += 0.5f*(tangent0 + tangent1);
+					tangents[vi[1]] += tangent0;
+					tangents[vi[2]] += 0.5f*(tangent0 + tangent1);
+					tangents[vi[3]] += tangent1;
+				}
+				else {
+					/* triangle tangent */
+					tangents[vi[0]] += tangent0;
+					tangents[vi[1]] += tangent0;
+					tangents[vi[2]] += tangent0;
+				}
+			}
+
+			/* normalize tangent vectors */
+			for(int i = 0; i < mesh->verts.size(); i++)
+				tangents[i] = normalize(tangents[i]);
+		}
+	}
 }
 
 static void create_subd_mesh(Mesh *mesh, BL::Mesh b_mesh, PointerRNA *cmesh, const vector<uint>& used_shaders)

intern/cycles/blender/blender_shader.cpp

@@ -315,6 +315,10 @@ static ShaderNode *add_node(BL::BlendData b_data, BL::Scene b_scene, ShaderGraph
 			node = new HoldoutNode();
 			break;
 		}
+		case BL::ShaderNode::type_BSDF_ANISOTROPIC: {
+			node = new WardBsdfNode();
+			break;
+		}
 		case BL::ShaderNode::type_BSDF_DIFFUSE: {
 			node = new DiffuseBsdfNode();
 			break;

intern/cycles/kernel/kernel_montecarlo.h

@@ -72,7 +72,7 @@ __device void to_unit_disk(float *x, float *y)
 
 __device void make_orthonormals_tangent(const float3 N, const float3 T, float3 *a, float3 *b)
 {
-	*b = cross(N, T);
+	*b = normalize(cross(N, T));
 	*a = cross(*b, N);
 }
 

intern/cycles/kernel/kernel_shader.h

@@ -93,6 +93,7 @@ __device_inline void shader_setup_from_ray(KernelGlobals *kg, ShaderData *sd,
 #ifdef __DPDU__
 	/* dPdu/dPdv */
 	triangle_dPdudv(kg, &sd->dPdu, &sd->dPdv, sd->prim);
+	sd->T = make_float3(0.0f, 0.0f, 0.0f);
 #endif
 
 #ifdef __INSTANCING__
@@ -117,6 +118,7 @@ __device_inline void shader_setup_from_ray(KernelGlobals *kg, ShaderData *sd,
 #ifdef __DPDU__
 		sd->dPdu = -sd->dPdu;
 		sd->dPdv = -sd->dPdv;
+		sd->T = make_float3(0.0f, 0.0f, 0.0f);
 #endif
 	}
 
@@ -208,6 +210,8 @@ __device void shader_setup_from_sample(KernelGlobals *kg, ShaderData *sd,
 		}
 #endif
 	}
+
+   	sd->T = make_float3(0.0f, 0.0f, 0.0f);
 #endif
 
 	/* backfacing test */
@@ -293,6 +297,7 @@ __device_inline void shader_setup_from_background(KernelGlobals *kg, ShaderData
 	/* dPdu/dPdv */
 	sd->dPdu = make_float3(0.0f, 0.0f, 0.0f);
 	sd->dPdv = make_float3(0.0f, 0.0f, 0.0f);
+	sd->T = make_float3(0.0f, 0.0f, 0.0f);
 #endif
 
 #ifdef __RAY_DIFFERENTIALS__

intern/cycles/kernel/kernel_types.h

@@ -447,6 +447,9 @@ typedef struct ShaderData {
 	/* differential of P w.r.t. parametric coordinates. note that dPdu is
 	 * not readily suitable as a tangent for shading on triangles. */
 	float3 dPdu, dPdv;
+
+	/* tangent for shading */
+	float3 T;
 #endif
 
 #ifdef __MULTI_CLOSURE__

intern/cycles/kernel/svm/bsdf_ward.h

@@ -67,7 +67,7 @@ __device float3 bsdf_ward_eval_reflect(const ShaderData *sd, const ShaderClosure
 	float m_ax = sc->data0;
 	float m_ay = sc->data1;
 	float3 m_N = sd->N;
-	float3 m_T = normalize(sd->dPdu);
+	float3 m_T = sd->T;
 
 	float cosNO = dot(m_N, I);
 	float cosNI = dot(m_N, omega_in);
@@ -90,6 +90,7 @@ __device float3 bsdf_ward_eval_reflect(const ShaderData *sd, const ShaderClosure
 		*pdf = exp_val / denom;
 		return make_float3 (out, out, out);
 	}
+
 	return make_float3 (0, 0, 0);
 }
 
@@ -108,7 +109,7 @@ __device int bsdf_ward_sample(const ShaderData *sd, const ShaderClosure *sc, flo
 	float m_ax = sc->data0;
 	float m_ay = sc->data1;
 	float3 m_N = sd->N;
-	float3 m_T = normalize(sd->dPdu);
+	float3 m_T = sd->T;
 
 	float cosNO = dot(m_N, sd->I);
 	if(cosNO > 0) {

intern/cycles/kernel/svm/svm.h

@@ -205,6 +205,14 @@ __device_noinline void svm_eval_nodes(KernelGlobals *kg, ShaderData *sd, ShaderT
 			case NODE_CLOSURE_WEIGHT:
 				svm_node_closure_weight(sd, stack, node.y);
 				break;
+#ifdef __DPDU__
+			case NODE_CLOSURE_SET_TANGENT:
+				svm_node_closure_set_tangent(sd, node.y, node.z, node.w);
+				break;
+			case NODE_CLOSURE_TANGENT:
+				svm_node_closure_tangent(sd, stack, node.y);
+				break;
+#endif
 			case NODE_EMISSION_WEIGHT:
 				svm_node_emission_weight(kg, sd, stack, node);
 				break;
@@ -261,14 +269,14 @@ __device_noinline void svm_eval_nodes(KernelGlobals *kg, ShaderData *sd, ShaderT
 				svm_node_camera(kg, sd, stack, node.y, node.z, node.w);
 				break;
 			case NODE_GEOMETRY:
-				svm_node_geometry(sd, stack, node.y, node.z);
+				svm_node_geometry(kg, sd, stack, node.y, node.z);
 				break;
 #ifdef __EXTRA_NODES__
 			case NODE_GEOMETRY_BUMP_DX:
-				svm_node_geometry_bump_dx(sd, stack, node.y, node.z);
+				svm_node_geometry_bump_dx(kg, sd, stack, node.y, node.z);
 				break;
 			case NODE_GEOMETRY_BUMP_DY:
-				svm_node_geometry_bump_dy(sd, stack, node.y, node.z);
+				svm_node_geometry_bump_dy(kg, sd, stack, node.y, node.z);
 				break;
 			case NODE_LIGHT_PATH:
 				svm_node_light_path(sd, stack, node.y, node.z, path_flag);

intern/cycles/kernel/svm/svm_closure.h

@@ -179,7 +179,7 @@ __device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *st
 			float roughness_u = param1;
 			float roughness_v = param2;
 
-			bsdf_ward_setup(sd, sc, normalize(sd->dPdu), roughness_u, roughness_v);
+			bsdf_ward_setup(sd, sc, normalize(sd->T), roughness_u, roughness_v);
 			break;
 		}
 #endif
@@ -425,5 +425,24 @@ __device void svm_node_add_closure(ShaderData *sd, float *stack, uint unused,
 #endif
 }
 
+#ifdef __DPDU__
+__device_inline void svm_node_closure_store_tangent(ShaderData *sd, float3 tangent)
+{
+	sd->T = normalize(tangent);
+}
+
+__device void svm_node_closure_set_tangent(ShaderData *sd, uint x, uint y, uint z)
+{
+	float3 tangent = make_float3(__int_as_float(x), __int_as_float(y), __int_as_float(z));
+	svm_node_closure_store_tangent(sd, tangent);
+}
+
+__device void svm_node_closure_tangent(ShaderData *sd, float *stack, uint tangent_offset)
+{
+	float3 tangent = stack_load_float3(stack, tangent_offset);
+	svm_node_closure_store_tangent(sd, tangent);
+}
+#endif
+
 CCL_NAMESPACE_END
 

intern/cycles/kernel/svm/svm_geometry.h

@@ -20,7 +20,7 @@ CCL_NAMESPACE_BEGIN
 
 /* Geometry Node */
 
-__device void svm_node_geometry(ShaderData *sd, float *stack, uint type, uint out_offset)
+__device void svm_node_geometry(KernelGlobals *kg, ShaderData *sd, float *stack, uint type, uint out_offset)
 {
 	float3 data;
 
@@ -28,7 +28,16 @@ __device void svm_node_geometry(ShaderData *sd, float *stack, uint type, uint ou
 		case NODE_GEOM_P: data = sd->P; break;
 		case NODE_GEOM_N: data = sd->N; break;
 #ifdef __DPDU__
-		case NODE_GEOM_T: data = normalize(sd->dPdu); break;
+		case NODE_GEOM_T: {
+			int attr_offset = find_attribute(kg, sd, ATTR_STD_TANGENT);
+
+			if(attr_offset == ATTR_STD_NOT_FOUND)
+				data = normalize(sd->dPdu);
+			else
+				data = triangle_attribute_float3(kg, sd, ATTR_ELEMENT_VERTEX, attr_offset, NULL, NULL);
+
+			break;
+		}
 #endif
 		case NODE_GEOM_I: data = sd->I; break;
 		case NODE_GEOM_Ng: data = sd->Ng; break;
@@ -40,7 +49,7 @@ __device void svm_node_geometry(ShaderData *sd, float *stack, uint type, uint ou
 	stack_store_float3(stack, out_offset, data);
 }
 
-__device void svm_node_geometry_bump_dx(ShaderData *sd, float *stack, uint type, uint out_offset)
+__device void svm_node_geometry_bump_dx(KernelGlobals *kg, ShaderData *sd, float *stack, uint type, uint out_offset)
 {
 #ifdef __RAY_DIFFERENTIALS__
 	float3 data;
@@ -48,16 +57,16 @@ __device void svm_node_geometry_bump_dx(ShaderData *sd, float *stack, uint type,
 	switch(type) {
 		case NODE_GEOM_P: data = sd->P + sd->dP.dx; break;
 		case NODE_GEOM_uv: data = make_float3(sd->u + sd->du.dx, sd->v + sd->dv.dx, 0.0f); break;
-		default: svm_node_geometry(sd, stack, type, out_offset); return;
+		default: svm_node_geometry(kg, sd, stack, type, out_offset); return;
 	}
 
 	stack_store_float3(stack, out_offset, data);
 #else
-	svm_node_geometry(sd, stack, type, out_offset);
+	svm_node_geometry(kg, sd, stack, type, out_offset);
 #endif
 }
 
-__device void svm_node_geometry_bump_dy(ShaderData *sd, float *stack, uint type, uint out_offset)
+__device void svm_node_geometry_bump_dy(KernelGlobals *kg, ShaderData *sd, float *stack, uint type, uint out_offset)
 {
 #ifdef __RAY_DIFFERENTIALS__
 	float3 data;
@@ -65,12 +74,12 @@ __device void svm_node_geometry_bump_dy(ShaderData *sd, float *stack, uint type,
 	switch(type) {
 		case NODE_GEOM_P: data = sd->P + sd->dP.dy; break;
 		case NODE_GEOM_uv: data = make_float3(sd->u + sd->du.dy, sd->v + sd->dv.dy, 0.0f); break;
-		default: svm_node_geometry(sd, stack, type, out_offset); return;
+		default: svm_node_geometry(kg, sd, stack, type, out_offset); return;
 	}
 
 	stack_store_float3(stack, out_offset, data);
 #else
-	svm_node_geometry(sd, stack, type, out_offset);
+	svm_node_geometry(kg, sd, stack, type, out_offset);
 #endif
 }
 

intern/cycles/kernel/svm/svm_types.h

@@ -92,7 +92,9 @@ typedef enum NodeType {
 	NODE_LIGHT_FALLOFF,
 	NODE_OBJECT_INFO,
 	NODE_PARTICLE_INFO,
-	NODE_TEX_BRICK
+	NODE_TEX_BRICK,
+	NODE_CLOSURE_SET_TANGENT,
+	NODE_CLOSURE_TANGENT,
 } NodeType;
 
 typedef enum NodeAttributeType {

intern/cycles/render/attribute.cpp

@@ -162,6 +162,8 @@ Attribute *AttributeSet::add(AttributeStandard std, ustring name)
 		attr = add(name, TypeDesc::TypeNormal, Attribute::FACE);
 	else if(std == ATTR_STD_UV)
 		attr = add(name, TypeDesc::TypePoint, Attribute::CORNER);
+	else if(std == ATTR_STD_TANGENT)
+		attr = add(name, TypeDesc::TypeVector, Attribute::VERTEX);
 	else if(std == ATTR_STD_GENERATED)
 		attr = add(name, TypeDesc::TypePoint, Attribute::VERTEX);
 	else if(std == ATTR_STD_POSITION_UNDEFORMED)

intern/cycles/render/graph.cpp

@@ -468,6 +468,12 @@ void ShaderGraph::default_inputs(bool do_osl)
 
 					connect(geom->output("Position"), input);
 				}
+				else if(input->default_value == ShaderInput::TANGENT) {
+					if(!geom)
+						geom = new GeometryNode();
+
+					connect(geom->output("Tangent"), input);
+				}
 			}
 		}
 	}

intern/cycles/render/graph.h

@@ -112,6 +112,7 @@ public:
 		INCOMING,
 		NORMAL,
 		POSITION,
+		TANGENT,
 		NONE
 	};
 

intern/cycles/render/nodes.cpp

@@ -1221,12 +1221,35 @@ WardBsdfNode::WardBsdfNode()
 {
 	closure = CLOSURE_BSDF_WARD_ID;
 
+	add_input("Tangent", SHADER_SOCKET_VECTOR, ShaderInput::TANGENT);
+
 	add_input("Roughness U", SHADER_SOCKET_FLOAT, 0.2f);
 	add_input("Roughness V", SHADER_SOCKET_FLOAT, 0.2f);
 }
 
+void WardBsdfNode::attributes(AttributeRequestSet *attributes)
+{
+	ShaderInput *tangent_in = input("Tangent");
+
+	if(!tangent_in->link)
+		attributes->add(ATTR_STD_TANGENT);
+
+	ShaderNode::attributes(attributes);
+}
+
 void WardBsdfNode::compile(SVMCompiler& compiler)
 {
+	ShaderInput *tangent_in = input("Tangent");
+
+	if(tangent_in->link) {
+		int attr = compiler.attribute(ATTR_STD_TANGENT);
+		compiler.stack_assign(tangent_in);
+		compiler.add_node(NODE_ATTR, attr, tangent_in->stack_offset, NODE_ATTR_FLOAT3);
+		compiler.add_node(NODE_CLOSURE_TANGENT, tangent_in->stack_offset);
+	}
+	else
+		compiler.add_node(NODE_CLOSURE_SET_TANGENT, tangent_in->value);
+
 	BsdfNode::compile(compiler, input("Roughness U"), input("Roughness V"));
 }
 
@@ -1566,6 +1589,14 @@ GeometryNode::GeometryNode()
 	add_output("Backfacing", SHADER_SOCKET_FLOAT);
 }
 
+void GeometryNode::attributes(AttributeRequestSet *attributes)
+{
+	if(!output("Tangent")->links.empty())
+		attributes->add(ATTR_STD_TANGENT);
+
+	ShaderNode::attributes(attributes);
+}
+
 void GeometryNode::compile(SVMCompiler& compiler)
 {
 	ShaderOutput *out;

intern/cycles/render/nodes.h

@@ -201,6 +201,7 @@ public:
 class WardBsdfNode : public BsdfNode {
 public:
 	SHADER_NODE_CLASS(WardBsdfNode)
+	void attributes(AttributeRequestSet *attributes);
 };
 
 class DiffuseBsdfNode : public BsdfNode {
@@ -278,6 +279,7 @@ public:
 class GeometryNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(GeometryNode)
+	void attributes(AttributeRequestSet *attributes);
 };
 
 class TextureCoordinateNode : public ShaderNode {

intern/cycles/util/util_types.h

@@ -449,6 +449,7 @@ typedef enum AttributeStandard {
 	ATTR_STD_VERTEX_NORMAL,
 	ATTR_STD_FACE_NORMAL,
 	ATTR_STD_UV,
+	ATTR_STD_TANGENT,
 	ATTR_STD_GENERATED,
 	ATTR_STD_POSITION_UNDEFORMED,
 	ATTR_STD_POSITION_UNDISPLACED,

source/blender/blenkernel/intern/node.c

@@ -2248,6 +2248,7 @@ static void registerShaderNodes(bNodeTreeType *ttype)
 	register_node_type_sh_particle_info(ttype);
 
 	register_node_type_sh_background(ttype);
+	register_node_type_sh_bsdf_anisotropic(ttype);
 	register_node_type_sh_bsdf_diffuse(ttype);
 	register_node_type_sh_bsdf_glossy(ttype);
 	register_node_type_sh_bsdf_glass(ttype);

source/blender/makesrna/intern/rna_nodetree_types.h

@@ -67,6 +67,7 @@ DefNode( ShaderNode,     SH_NODE_ADD_SHADER,         0,                      "AD
 DefNode( ShaderNode,     SH_NODE_ATTRIBUTE,          def_sh_attribute,       "ATTRIBUTE",          Attribute,        "Attribute",         ""       )
 DefNode( ShaderNode,     SH_NODE_BACKGROUND,         0,                      "BACKGROUND",         Background,       "Background",        ""       )
 DefNode( ShaderNode,     SH_NODE_HOLDOUT,            0,                      "HOLDOUT",            Holdout,          "Holdout",           ""       )
+DefNode( ShaderNode,     SH_NODE_BSDF_ANISOTROPIC,   0,                      "BSDF_ANISOTROPIC",   BsdfAnisotropic,  "Anisotropic Bsdf",  ""       )
 DefNode( ShaderNode,     SH_NODE_BSDF_DIFFUSE,       0,                      "BSDF_DIFFUSE",       BsdfDiffuse,      "Diffuse Bsdf",      ""       )
 DefNode( ShaderNode,     SH_NODE_BSDF_GLOSSY,        def_glossy,             "BSDF_GLOSSY",        BsdfGlossy,       "Glossy Bsdf",       ""       )
 DefNode( ShaderNode,     SH_NODE_BSDF_GLASS,         def_glossy,             "BSDF_GLASS",         BsdfGlass,        "Glass Bsdf",        ""       )

source/blender/nodes/CMakeLists.txt

@@ -146,7 +146,7 @@ set(SRC
 	shader/nodes/node_shader_vectMath.c
 	shader/nodes/node_shader_attribute.c
 	shader/nodes/node_shader_background.c
-	# shader/nodes/node_shader_bsdf_anisotropic.c  # XXX, why not included?
+	shader/nodes/node_shader_bsdf_anisotropic.c
 	shader/nodes/node_shader_bsdf_diffuse.c
 	shader/nodes/node_shader_bsdf_glossy.c
 	shader/nodes/node_shader_bsdf_glass.c

source/blender/nodes/NOD_shader.h

@@ -88,6 +88,7 @@ void register_node_type_sh_bsdf_glass(struct bNodeTreeType *ttype);
 void register_node_type_sh_bsdf_translucent(struct bNodeTreeType *ttype);
 void register_node_type_sh_bsdf_transparent(struct bNodeTreeType *ttype);
 void register_node_type_sh_bsdf_velvet(struct bNodeTreeType *ttype);
+void register_node_type_sh_bsdf_anisotropic(struct bNodeTreeType *ttype);
 void register_node_type_sh_emission(struct bNodeTreeType *ttype);
 void register_node_type_sh_holdout(struct bNodeTreeType *ttype);
 void register_node_type_sh_volume_transparent(struct bNodeTreeType *ttype);

source/blender/nodes/shader/nodes/node_shader_bsdf_anisotropic.c

@@ -51,7 +51,7 @@ void register_node_type_sh_bsdf_anisotropic(bNodeTreeType *ttype)
 {
 	static bNodeType ntype;
 
-	node_type_base(ttype, &ntype, SH_NODE_BSDF_ANISOTROPIC, "Glossy Anisotropic BSDF", NODE_CLASS_SHADER, 0);
+	node_type_base(ttype, &ntype, SH_NODE_BSDF_ANISOTROPIC, "Anisotropic BSDF", NODE_CLASS_SHADER, 0);
 	node_type_compatibility(&ntype, NODE_NEW_SHADING);
 	node_type_socket_templates(&ntype, sh_node_bsdf_anisotropic_in, sh_node_bsdf_anisotropic_out);
 	node_type_size(&ntype, 150, 60, 200);