Cycles: add update flags to Node and SocketType

Those flags are meant for detecting which socket has changed, so in the
future we can have more granular updates.

`Node` now stores an `update_flags` member which is modified every time
a socket is changed though `Node::set`. The flags are or-able bits
stored in `SocketType` instances. Each `SocketType` stores a unique bit
out of 64, for the 64 bits of an uint64_t; the bit
corresponds to the index of the socket in the `Node`'s sockets array +
1, so the socket at index 5 will have the 6th bit set as its flag. This
limits us to 64 sockets per Node, which should be plenty for the current
set of `Nodes` that we have.

This does not change the behavior of other parts of Cycles.

This is part of T79131.

Reviewed By: brecht

Maniphest Tasks: T79131

Differential Revision: https://developer.blender.org/D8644

4 files changed, 91 insertions, 18 deletions

diff --git a/intern/cycles/graph/node.cpp b/intern/cycles/graph/node.cpp
index 37387053d97..4d32d52aa83 100644
--- a/intern/cycles/graph/node.cpp
+++ b/intern/cycles/graph/node.cpp
@@ -35,6 +35,7 @@ Node::Node(const NodeType *type_, ustring name_) : name(name_), type(type_)
   assert(type);
 
   owner = nullptr;
+  socket_modified = ~0;
 
   /* assign non-empty name, convenient for debugging */
   if (name.empty()) {
@@ -74,37 +75,37 @@ static bool is_socket_array_float3(const SocketType &socket)
 void Node::set(const SocketType &input, bool value)
 {
   assert(input.type == SocketType::BOOLEAN);
-  get_socket_value<bool>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, int value)
 {
   assert((input.type == SocketType::INT || input.type == SocketType::ENUM));
-  get_socket_value<int>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, uint value)
 {
   assert(input.type == SocketType::UINT);
-  get_socket_value<uint>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, float value)
 {
   assert(input.type == SocketType::FLOAT);
-  get_socket_value<float>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, float2 value)
 {
   assert(input.type == SocketType::FLOAT);
-  get_socket_value<float2>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, float3 value)
 {
   assert(is_socket_float3(input));
-  get_socket_value<float3>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, const char *value)
@@ -115,12 +116,12 @@ void Node::set(const SocketType &input, const char *value)
 void Node::set(const SocketType &input, ustring value)
 {
   if (input.type == SocketType::STRING) {
-    get_socket_value<ustring>(this, input) = value;
+    set_if_different(input, value);
   }
   else if (input.type == SocketType::ENUM) {
     const NodeEnum &enm = *input.enum_values;
     if (enm.exists(value)) {
-      get_socket_value<int>(this, input) = enm[value];
+      set_if_different(input, enm[value]);
     }
     else {
       assert(0);
@@ -134,62 +135,62 @@ void Node::set(const SocketType &input, ustring value)
 void Node::set(const SocketType &input, const Transform &value)
 {
   assert(input.type == SocketType::TRANSFORM);
-  get_socket_value<Transform>(this, input) = value;
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, Node *value)
 {
   assert(input.type == SocketType::NODE);
-  get_socket_value<Node *>(this, input) = value;
+  set_if_different(input, value);
 }
 
 /* set array values */
 void Node::set(const SocketType &input, array<bool> &value)
 {
   assert(input.type == SocketType::BOOLEAN_ARRAY);
-  get_socket_value<array<bool>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<int> &value)
 {
   assert(input.type == SocketType::INT_ARRAY);
-  get_socket_value<array<int>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<float> &value)
 {
   assert(input.type == SocketType::FLOAT_ARRAY);
-  get_socket_value<array<float>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<float2> &value)
 {
   assert(input.type == SocketType::FLOAT_ARRAY);
-  get_socket_value<array<float2>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<float3> &value)
 {
   assert(is_socket_array_float3(input));
-  get_socket_value<array<float3>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<ustring> &value)
 {
   assert(input.type == SocketType::STRING_ARRAY);
-  get_socket_value<array<ustring>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<Transform> &value)
 {
   assert(input.type == SocketType::TRANSFORM_ARRAY);
-  get_socket_value<array<Transform>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 void Node::set(const SocketType &input, array<Node *> &value)
 {
   assert(input.type == SocketType::TRANSFORM_ARRAY);
-  get_socket_value<array<Node *>>(this, input).steal_data(value);
+  set_if_different(input, value);
 }
 
 /* get values */
@@ -696,4 +697,56 @@ void Node::set_owner(const NodeOwner *owner_)
   owner = owner_;
 }
 
+bool Node::socket_is_modified(const SocketType &input) const
+{
+  return (socket_modified & input.modified_flag_bit) != 0;
+}
+
+bool Node::is_modified()
+{
+  return socket_modified != 0;
+}
+
+void Node::tag_modified()
+{
+  socket_modified = ~0u;
+}
+
+void Node::clear_modified()
+{
+  socket_modified = 0;
+}
+
+template<typename T> void Node::set_if_different(const SocketType &input, T value)
+{
+  if (get_socket_value<T>(this, input) == value) {
+    return;
+  }
+
+  get_socket_value<T>(this, input) = value;
+  socket_modified |= input.modified_flag_bit;
+}
+
+template<typename T> void Node::set_if_different(const SocketType &input, array<T> &value)
+{
+  if (!socket_is_modified(input)) {
+    if (get_socket_value<array<T>>(this, input) == value) {
+      return;
+    }
+  }
+
+  get_socket_value<array<T>>(this, input).steal_data(value);
+  socket_modified |= input.modified_flag_bit;
+}
+
+void Node::print_modified_sockets() const
+{
+  printf("Node : %s\n", name.c_str());
+  for (auto &socket : type->inputs) {
+    if (socket_is_modified(socket)) {
+      printf("-- socket modified : %s\n", socket.name.c_str());
+    }
+  }
+}
+
 CCL_NAMESPACE_END
diff --git a/intern/cycles/graph/node.h b/intern/cycles/graph/node.h
index 3c84dbdb4a7..16bd5e4358a 100644
--- a/intern/cycles/graph/node.h
+++ b/intern/cycles/graph/node.h
@@ -101,6 +101,15 @@ struct Node {
   /* Type testing, taking into account base classes. */
   bool is_a(const NodeType *type);
 
+  bool socket_is_modified(const SocketType &input) const;
+
+  bool is_modified();
+
+  void tag_modified();
+  void clear_modified();
+
+  void print_modified_sockets() const;
+
   ustring name;
   const NodeType *type;
 
@@ -109,6 +118,12 @@ struct Node {
 
  protected:
   const NodeOwner *owner;
+
+  SocketModifiedFlags socket_modified;
+
+  template<typename T> void set_if_different(const SocketType &input, T value);
+
+  template<typename T> void set_if_different(const SocketType &input, array<T> &value);
 };
 
 CCL_NAMESPACE_END
diff --git a/intern/cycles/graph/node_type.cpp b/intern/cycles/graph/node_type.cpp
index 0283ed7c817..0ec421023a2 100644
--- a/intern/cycles/graph/node_type.cpp
+++ b/intern/cycles/graph/node_type.cpp
@@ -167,6 +167,8 @@ void NodeType::register_input(ustring name,
   socket.enum_values = enum_values;
   socket.node_type = node_type;
   socket.flags = flags | extra_flags;
+  assert(inputs.size() < std::numeric_limits<SocketModifiedFlags>::digits);
+  socket.modified_flag_bit = (1ul << inputs.size());
   inputs.push_back(socket);
 }
 
diff --git a/intern/cycles/graph/node_type.h b/intern/cycles/graph/node_type.h
index a79d44b82f3..0d182945e16 100644
--- a/intern/cycles/graph/node_type.h
+++ b/intern/cycles/graph/node_type.h
@@ -28,6 +28,8 @@ CCL_NAMESPACE_BEGIN
 struct Node;
 struct NodeType;
 
+typedef uint64_t SocketModifiedFlags;
+
 /* Socket Type */
 
 struct SocketType {
@@ -88,6 +90,7 @@ struct SocketType {
   const NodeType **node_type;
   int flags;
   ustring ui_name;
+  SocketModifiedFlags modified_flag_bit;
 
   size_t size() const;
   bool is_array() const;