Fix T82336: Cycles standard attributes missing in displacement shaders

Standard attributes are not added to the attributes requests when
shaders only have displacement. This is because nodes are only
considering the case when the surface socket is connected.

To support this, added `Shader.has_surface_link()` which checks for both
cases (`has_surface` and `has_displacement`) and replaces all checks on
`Shader.has_surface`.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D12240

3 files changed, 20 insertions, 12 deletions

diff --git a/intern/cycles/render/graph.cpp b/intern/cycles/render/graph.cpp
index cdaa878e830..e9da48b624d 100644
--- a/intern/cycles/render/graph.cpp
+++ b/intern/cycles/render/graph.cpp
@@ -158,13 +158,13 @@ void ShaderNode::attributes(Shader *shader, AttributeRequestSet *attributes)
   foreach (ShaderInput *input, inputs) {
     if (!input->link) {
       if (input->flags() & SocketType::LINK_TEXTURE_GENERATED) {
-        if (shader->has_surface)
+        if (shader->has_surface_link())
           attributes->add(ATTR_STD_GENERATED);
         if (shader->has_volume)
           attributes->add(ATTR_STD_GENERATED_TRANSFORM);
       }
       else if (input->flags() & SocketType::LINK_TEXTURE_UV) {
-        if (shader->has_surface)
+        if (shader->has_surface_link())
           attributes->add(ATTR_STD_UV);
       }
     }
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index 42cba342bf8..795166bcf4c 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -350,7 +350,7 @@ void ImageTextureNode::attributes(Shader *shader, AttributeRequestSet *attribute
 #ifdef WITH_PTEX
   /* todo: avoid loading other texture coordinates when using ptex,
    * and hide texture coordinate socket in the UI */
-  if (shader->has_surface && string_endswith(filename, ".ptx")) {
+  if (shader->has_surface_link() && string_endswith(filename, ".ptx")) {
     /* ptex */
     attributes->add(ATTR_STD_PTEX_FACE_ID);
     attributes->add(ATTR_STD_PTEX_UV);
@@ -552,7 +552,7 @@ ImageParams EnvironmentTextureNode::image_params() const
 void EnvironmentTextureNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
 #ifdef WITH_PTEX
-  if (shader->has_surface && string_endswith(filename, ".ptx")) {
+  if (shader->has_surface_link() && string_endswith(filename, ".ptx")) {
     /* ptex */
     attributes->add(ATTR_STD_PTEX_FACE_ID);
     attributes->add(ATTR_STD_PTEX_UV);
@@ -2319,7 +2319,7 @@ AnisotropicBsdfNode::AnisotropicBsdfNode() : BsdfNode(get_node_type())
 
 void AnisotropicBsdfNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface) {
+  if (shader->has_surface_link()) {
     ShaderInput *tangent_in = input("Tangent");
 
     if (!tangent_in->link)
@@ -2843,7 +2843,7 @@ bool PrincipledBsdfNode::has_surface_bssrdf()
 
 void PrincipledBsdfNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface) {
+  if (shader->has_surface_link()) {
     ShaderInput *tangent_in = input("Tangent");
 
     if (!tangent_in->link)
@@ -3684,7 +3684,7 @@ GeometryNode::GeometryNode() : ShaderNode(get_node_type())
 
 void GeometryNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface) {
+  if (shader->has_surface_link()) {
     if (!output("Tangent")->links.empty()) {
       attributes->add(ATTR_STD_GENERATED);
     }
@@ -3830,7 +3830,7 @@ TextureCoordinateNode::TextureCoordinateNode() : ShaderNode(get_node_type())
 
 void TextureCoordinateNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface) {
+  if (shader->has_surface_link()) {
     if (!from_dupli) {
       if (!output("Generated")->links.empty())
         attributes->add(ATTR_STD_GENERATED);
@@ -4388,7 +4388,7 @@ HairInfoNode::HairInfoNode() : ShaderNode(get_node_type())
 
 void HairInfoNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface) {
+  if (shader->has_surface_link()) {
     ShaderOutput *intercept_out = output("Intercept");
 
     if (!intercept_out->links.empty())
@@ -6744,7 +6744,7 @@ NormalMapNode::NormalMapNode() : ShaderNode(get_node_type())
 
 void NormalMapNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface && space == NODE_NORMAL_MAP_TANGENT) {
+  if (shader->has_surface_link() && space == NODE_NORMAL_MAP_TANGENT) {
     if (attribute.empty()) {
       attributes->add(ATTR_STD_UV_TANGENT);
       attributes->add(ATTR_STD_UV_TANGENT_SIGN);
@@ -6838,7 +6838,7 @@ TangentNode::TangentNode() : ShaderNode(get_node_type())
 
 void TangentNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface) {
+  if (shader->has_surface_link()) {
     if (direction_type == NODE_TANGENT_UVMAP) {
       if (attribute.empty())
         attributes->add(ATTR_STD_UV_TANGENT);
@@ -7021,7 +7021,7 @@ void VectorDisplacementNode::constant_fold(const ConstantFolder &folder)
 
 void VectorDisplacementNode::attributes(Shader *shader, AttributeRequestSet *attributes)
 {
-  if (shader->has_surface && space == NODE_NORMAL_MAP_TANGENT) {
+  if (shader->has_surface_link() && space == NODE_NORMAL_MAP_TANGENT) {
     if (attribute.empty()) {
       attributes->add(ATTR_STD_UV_TANGENT);
       attributes->add(ATTR_STD_UV_TANGENT_SIGN);
diff --git a/intern/cycles/render/shader.h b/intern/cycles/render/shader.h
index 50c8bed4669..c65cac351a4 100644
--- a/intern/cycles/render/shader.h
+++ b/intern/cycles/render/shader.h
@@ -154,6 +154,14 @@ class Shader : public Node {
   void tag_update(Scene *scene);
   void tag_used(Scene *scene);
 
+  /* Return true when either of the surface or displacement socket of the output node is linked.
+   * This should be used to ensure that surface attributes are also requested even when only the
+   * displacement socket is linked. */
+  bool has_surface_link() const
+  {
+    return has_surface || has_displacement;
+  }
+
   bool need_update_geometry() const;
 };