1 files changed, 47 insertions, 0 deletions
diff --git a/source/blender/compositor/intern/COM_NodeOperation.cc b/source/blender/compositor/intern/COM_NodeOperation.cc
index 1b87cdf72fb..3bbd1b22d60 100644
--- a/source/blender/compositor/intern/COM_NodeOperation.cc
+++ b/source/blender/compositor/intern/COM_NodeOperation.cc
@@ -41,6 +41,53 @@ NodeOperation::NodeOperation()
   this->m_btree = nullptr;
 }
 
+/**
+ * Generate a hash that identifies the operation result in the current execution.
+ * Requires `hash_output_params` to be implemented, otherwise `std::nullopt` is returned.
+ * If the operation parameters or its linked inputs change, the hash must be re-generated.
+ */
+std::optional<NodeOperationHash> NodeOperation::generate_hash()
+{
+  params_hash_ = get_default_hash_2(m_width, m_height);
+
+  /* Hash subclasses params. */
+  is_hash_output_params_implemented_ = true;
+  hash_output_params();
+  if (!is_hash_output_params_implemented_) {
+    return std::nullopt;
+  }
+
+  hash_param(getOutputSocket()->getDataType());
+  NodeOperationHash hash;
+  hash.params_hash_ = params_hash_;
+
+  hash.parents_hash_ = 0;
+  for (NodeOperationInput &socket : m_inputs) {
+    if (!socket.isConnected()) {
+      continue;
+    }
+
+    NodeOperation &input = socket.getLink()->getOperation();
+    const bool is_constant = input.get_flags().is_constant_operation;
+    combine_hashes(hash.parents_hash_, get_default_hash(is_constant));
+    if (is_constant) {
+      const float *elem = ((ConstantOperation *)&input)->get_constant_elem();
+      const int num_channels = COM_data_type_num_channels(socket.getDataType());
+      for (const int i : IndexRange(num_channels)) {
+        combine_hashes(hash.parents_hash_, get_default_hash(elem[i]));
+      }
+    }
+    else {
+      combine_hashes(hash.parents_hash_, get_default_hash(input.get_id()));
+    }
+  }
+
+  hash.type_hash_ = typeid(*this).hash_code();
+  hash.operation_ = this;
+
+  return hash;
+}
+
 NodeOperationOutput *NodeOperation::getOutputSocket(unsigned int index)
 {
   return &m_outputs[index];