Nodes: Generate multi-function network from node tree

This adds new callbacks to `bNodeSocketType` and `bNodeType`.
Those are used to generate a multi-function network from a node
tree. Later, this network is evaluated on e.g. particle data.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D8169

1 files changed, 32 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index bdcbe2129c8..acd4c75befd 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -101,6 +101,30 @@ typedef struct bNodeSocketTemplate {
   char identifier[64];      /* generated from name */
 } bNodeSocketTemplate;
 
+/* Use `void *` for callbacks that require C++. This is rather ugly, but works well for now. This
+ * would not be necessary if we would use bNodeSocketType and bNodeType only in C++ code.
+ * However, achieving this requires quite a few changes currently. */
+#ifdef __cplusplus
+namespace blender {
+namespace bke {
+class SocketMFNetworkBuilder;
+class NodeMFNetworkBuilder;
+}  // namespace bke
+namespace fn {
+class MFDataType;
+}
+}  // namespace blender
+
+using NodeExpandInMFNetworkFunction = void (*)(blender::bke::NodeMFNetworkBuilder &builder);
+using SocketGetMFDataTypeFunction = blender::fn::MFDataType (*)();
+using SocketExpandInMFNetworkFunction = void (*)(blender::bke::SocketMFNetworkBuilder &builder);
+
+#else
+typedef void *NodeExpandInMFNetworkFunction;
+typedef void *SocketGetMFDataTypeFunction;
+typedef void *SocketExpandInMFNetworkFunction;
+#endif
+
 /**
  * \brief Defines a socket type.
  *
@@ -153,6 +177,11 @@ typedef struct bNodeSocketType {
 
   /* Callback to free the socket type. */
   void (*free_self)(struct bNodeSocketType *stype);
+
+  /* Returns the multi-function data type of this socket type. */
+  SocketGetMFDataTypeFunction get_mf_data_type;
+  /* Expands the socket into a multi-function node that outputs the socket value. */
+  SocketExpandInMFNetworkFunction expand_in_mf_network;
 } bNodeSocketType;
 
 typedef void *(*NodeInitExecFunction)(struct bNodeExecContext *context,
@@ -267,6 +296,9 @@ typedef struct bNodeType {
   /* gpu */
   NodeGPUExecFunction gpufunc;
 
+  /* Expands the bNode into nodes in a multi-function network, which will be evaluated later on. */
+  NodeExpandInMFNetworkFunction expand_in_mf_network;
+
   /* RNA integration */
   ExtensionRNA rna_ext;
 } bNodeType;