Geometry Nodes: improve geometry nodes evaluator internal api

This is a first step towards T87620.
It should not have any functional changes.

Goals of this refactor:
* Move the evaluator out of `MOD_nodes.cc`. That makes it easier to
  improve it in isolation.
* Extract core input/out parameter management out of `GeoNodeExecParams`.
  Managing this is the responsibility of the evaluator. This separation of
  concerns will be useful once we have lazy evaluation of certain inputs/outputs.

Differential Revision: https://developer.blender.org/D11085

1 files changed, 56 insertions, 0 deletions

diff --git a/source/blender/modifiers/intern/MOD_nodes_evaluator.hh b/source/blender/modifiers/intern/MOD_nodes_evaluator.hh
new file mode 100644
index 00000000000..3d9a03350f7
--- /dev/null
+++ b/source/blender/modifiers/intern/MOD_nodes_evaluator.hh
@@ -0,0 +1,56 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software  Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include "BLI_map.hh"
+
+#include "NOD_derived_node_tree.hh"
+#include "NOD_node_tree_multi_function.hh"
+
+#include "FN_generic_pointer.hh"
+
+#include "BKE_persistent_data_handle.hh"
+
+#include "DNA_modifier_types.h"
+
+namespace blender::modifiers::geometry_nodes {
+
+using namespace nodes::derived_node_tree_types;
+using bke::PersistentDataHandleMap;
+using fn::GMutablePointer;
+using fn::GPointer;
+
+using LogSocketValueFn = std::function<void(DSocket, Span<GPointer>)>;
+
+struct GeometryNodesEvaluationParams {
+  blender::LinearAllocator<> allocator;
+
+  Map<DOutputSocket, GMutablePointer> input_values;
+  Vector<DInputSocket> output_sockets;
+  nodes::MultiFunctionByNode *mf_by_node;
+  const PersistentDataHandleMap *handle_map;
+  const NodesModifierData *modifier_;
+  Depsgraph *depsgraph;
+  Object *self_object;
+  LogSocketValueFn log_socket_value_fn;
+
+  Vector<GMutablePointer> r_output_values;
+};
+
+void evaluate_geometry_nodes(GeometryNodesEvaluationParams &params);
+
+}  // namespace blender::modifiers::geometry_nodes