Geometry Nodes: Add 'Signed Distance' input node

Adds an input node Signed Distance that can
be used to refer to the distance-grid of an SDF volume.
Right now it's experimental and can be enabled by enabling
"New Volume Nodes" in the preferences.

It returns a float AttributeFieldInput called 'distance' which
can tell Volume nodes which grid to get.

See #103248.

scripts/startup/bl_ui/node_add_menu_geometry.py

@@ -614,6 +614,7 @@ class NODE_MT_category_GEO_VOLUME(Menu):
             node_add_menu.add_node_type(layout, "GeometryNodeMeanFilterSDFVolume")
             node_add_menu.add_node_type(layout, "GeometryNodeOffsetSDFVolume")
             node_add_menu.add_node_type(layout, "GeometryNodeSDFVolumeSphere")
+            node_add_menu.add_node_type(layout, "GeometryNodeInputSignedDistance")
         node_add_menu.draw_assets_for_catalog(layout, self.bl_label)
 
 

source/blender/blenkernel/BKE_node.h

@@ -1587,6 +1587,7 @@ void BKE_nodetree_remove_layer_n(struct bNodeTree *ntree, struct Scene *scene, i
 /* Function nodes use the range starting at 1200. */
 #define GEO_NODE_SIMULATION_INPUT 2100
 #define GEO_NODE_SIMULATION_OUTPUT 2101
+#define GEO_NODE_INPUT_SIGNED_DISTANCE 2102
 
 /** \} */
 

source/blender/nodes/NOD_static_types.h

@@ -349,6 +349,7 @@ DefNode(GeometryNode, GEO_NODE_INPUT_RADIUS, 0, "INPUT_RADIUS", InputRadius, "Ra
 DefNode(GeometryNode, GEO_NODE_INPUT_SCENE_TIME, 0, "INPUT_SCENE_TIME", InputSceneTime, "Scene Time", "Retrieve the current time in the scene's animation in units of seconds or frames")
 DefNode(GeometryNode, GEO_NODE_INPUT_SHADE_SMOOTH, 0, "INPUT_SHADE_SMOOTH", InputShadeSmooth, "Is Shade Smooth", "Retrieve whether each face is marked for smooth shading")
 DefNode(GeometryNode, GEO_NODE_INPUT_SHORTEST_EDGE_PATHS, 0, "SHORTEST_EDGE_PATHS", InputShortestEdgePaths, "Shortest Edge Paths", "")
+DefNode(GeometryNode, GEO_NODE_INPUT_SIGNED_DISTANCE, 0, "SIGNED_DISTANCE", InputSignedDistance, "Signed Distance", "Retrieve the signed distance field grid called 'distance' from a volume")
 DefNode(GeometryNode, GEO_NODE_INPUT_SPLINE_CYCLIC, 0, "INPUT_SPLINE_CYCLIC",InputSplineCyclic, "Is Spline Cyclic", "Retrieve whether each spline endpoint connects to the beginning")
 DefNode(GeometryNode, GEO_NODE_INPUT_SPLINE_LENGTH, 0, "SPLINE_LENGTH", SplineLength, "Spline Length", "Retrieve the total length of each spline, as a distance or as a number of points")
 DefNode(GeometryNode, GEO_NODE_INPUT_SPLINE_RESOLUTION, 0, "INPUT_SPLINE_RESOLUTION", InputSplineResolution, "Spline Resolution", "Retrieve the number of evaluated points that will be generated for every control point on curves")

source/blender/nodes/geometry/CMakeLists.txt

@@ -102,6 +102,7 @@ set(SRC
   nodes/node_geo_input_scene_time.cc
   nodes/node_geo_input_shade_smooth.cc
   nodes/node_geo_input_shortest_edge_paths.cc
+  nodes/node_geo_input_signed_distance.cc
   nodes/node_geo_input_spline_cyclic.cc
   nodes/node_geo_input_spline_length.cc
   nodes/node_geo_input_spline_resolution.cc

source/blender/nodes/geometry/node_geometry_register.cc

@@ -86,6 +86,7 @@ void register_geometry_nodes()
   register_node_type_geo_input_scene_time();
   register_node_type_geo_input_shade_smooth();
   register_node_type_geo_input_shortest_edge_paths();
+  register_node_type_geo_input_signed_distance();
   register_node_type_geo_input_spline_cyclic();
   register_node_type_geo_input_spline_length();
   register_node_type_geo_input_spline_resolution();

source/blender/nodes/geometry/node_geometry_register.hh

@@ -83,6 +83,7 @@ void register_node_type_geo_input_radius();
 void register_node_type_geo_input_scene_time();
 void register_node_type_geo_input_shade_smooth();
 void register_node_type_geo_input_shortest_edge_paths();
+void register_node_type_geo_input_signed_distance();
 void register_node_type_geo_input_spline_cyclic();
 void register_node_type_geo_input_spline_length();
 void register_node_type_geo_input_spline_resolution();

source/blender/nodes/geometry/nodes/node_geo_input_signed_distance.cc

@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "NOD_add_node_search.hh"
+#include "NOD_socket_search_link.hh"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_input_signed_distance_cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_output<decl::Float>(N_("Signed Distance")).field_source();
+}
+
+static void search_node_add_ops(GatherAddNodeSearchParams &params)
+{
+  if (U.experimental.use_new_volume_nodes) {
+    blender::nodes::search_node_add_ops_for_basic_node(params);
+  }
+}
+
+static void search_link_ops(GatherLinkSearchOpParams &params)
+{
+  if (U.experimental.use_new_volume_nodes) {
+    blender::nodes::search_link_ops_for_basic_node(params);
+  }
+}
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  Field<float> signed_distance_field{AttributeFieldInput::Create<float>("distance")};
+  params.set_output("Signed Distance", std::move(signed_distance_field));
+}
+
+}  // namespace blender::nodes::node_geo_input_signed_distance_cc
+
+void register_node_type_geo_input_signed_distance()
+{
+  namespace file_ns = blender::nodes::node_geo_input_signed_distance_cc;
+
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_INPUT_SIGNED_DISTANCE, "Signed Distance", NODE_CLASS_INPUT);
+  ntype.geometry_node_execute = file_ns::node_geo_exec;
+  ntype.declare = file_ns::node_declare;
+  ntype.gather_add_node_search_ops = file_ns::search_node_add_ops;
+  ntype.gather_link_search_ops = file_ns::search_link_ops;
+  nodeRegisterType(&ntype);
+}