Geometry Nodes: new Viewer node

This adds a viewer node similar to the one in the compositor.
The icon in the headers of nodes is removed because it served
the same purpose and is not necessary anymore.

Node outputs can be connected to the active viewer using
ctrl+shift+LMB, just like in the compositor. Right now this collides
with the shortcut used in the node wrangler addon, which will
be changed separately.

As of now, the viewed geometry is only visible in the spreadsheet.
Viewport visualization will be added separately.

There are a couple of benefits of using a viewer node compared
to the old approach with the icon in the node header:
* Better support for nodes that have more than one geometry output.
* It's more consistent with the compositor.
* If attributes become decoupled from geometry in the future,
  the viewer can have a separate input for the attribute to visualize.
* The viewer node could potentially have visualization settings.
* Allows to keep "visualization points" around by having multiple
  viewer nodes.
* Less visual clutter in node headers.

Differential Revision: https://developer.blender.org/D11470

4 files changed, 34 insertions, 0 deletions

diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index 77d2f043b64..49e40060c0f 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -206,6 +206,7 @@ set(SRC
   geometry/nodes/node_geo_switch.cc
   geometry/nodes/node_geo_transform.cc
   geometry/nodes/node_geo_triangulate.cc
+  geometry/nodes/node_geo_viewer.cc
   geometry/nodes/node_geo_volume_to_mesh.cc
   geometry/node_geometry_exec.cc
   geometry/node_geometry_tree.cc
diff --git a/source/blender/nodes/NOD_geometry.h b/source/blender/nodes/NOD_geometry.h
index 3e41c37ca75..5422eb6a5bf 100644
--- a/source/blender/nodes/NOD_geometry.h
+++ b/source/blender/nodes/NOD_geometry.h
@@ -95,6 +95,7 @@ void register_node_type_geo_subdivision_surface(void);
 void register_node_type_geo_switch(void);
 void register_node_type_geo_transform(void);
 void register_node_type_geo_triangulate(void);
+void register_node_type_geo_viewer(void);
 void register_node_type_geo_volume_to_mesh(void);
 
 #ifdef __cplusplus
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index f6063039bfc..1d906033128 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -333,6 +333,7 @@ DefNode(GeometryNode, GEO_NODE_SUBDIVISION_SURFACE, 0, "SUBDIVISION_SURFACE", Su
 DefNode(GeometryNode, GEO_NODE_SWITCH, def_geo_switch, "SWITCH", Switch, "Switch", "")
 DefNode(GeometryNode, GEO_NODE_TRANSFORM, 0, "TRANSFORM", Transform, "Transform", "")
 DefNode(GeometryNode, GEO_NODE_TRIANGULATE, def_geo_triangulate, "TRIANGULATE", Triangulate, "Triangulate", "")
+DefNode(GeometryNode, GEO_NODE_VIEWER, 0, "VIEWER", Viewer, "Viewer", "")
 DefNode(GeometryNode, GEO_NODE_VOLUME_TO_MESH, def_geo_volume_to_mesh, "VOLUME_TO_MESH", VolumeToMesh, "Volume to Mesh", "")
 
 /* undefine macros */
diff --git a/source/blender/nodes/geometry/nodes/node_geo_viewer.cc b/source/blender/nodes/geometry/nodes/node_geo_viewer.cc
new file mode 100644
index 00000000000..f0b91f49f52
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_viewer.cc
@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+
+#include "node_geometry_util.hh"
+
+static bNodeSocketTemplate geo_node_viewer_in[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {-1, ""},
+};
+
+void register_node_type_geo_viewer()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_VIEWER, "Viewer", NODE_CLASS_OUTPUT, 0);
+  node_type_socket_templates(&ntype, geo_node_viewer_in, nullptr);
+  nodeRegisterType(&ntype);
+}