Geometry Nodes: new Material Replace node

This node can change all faces that use a specific material to use a
different material. Using this node is significantly more efficient
than creating a selection from all faces with a specific material
index and then using the Material Assign node.

Ref T88055.

Differential Revision: https://developer.blender.org/D11325

release/scripts/startup/nodeitems_builtins.py

@@ -528,6 +528,7 @@ geometry_node_categories = [
     ]),
     GeometryNodeCategory("GEO_MATERIAL", "Material", items=[
         NodeItem("GeometryNodeMaterialAssign"),
+        NodeItem("GeometryNodeMaterialReplace"),
     ]),
     GeometryNodeCategory("GEO_MESH", "Mesh", items=[
         NodeItem("GeometryNodeBoolean"),

source/blender/blenkernel/BKE_node.h

@@ -1425,6 +1425,7 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_ATTRIBUTE_VECTOR_ROTATE 1048
 #define GEO_NODE_MATERIAL_ASSIGN 1049
 #define GEO_NODE_INPUT_MATERIAL 1050
+#define GEO_NODE_MATERIAL_REPLACE 1051
 
 /** \} */
 

source/blender/blenkernel/intern/node.cc

@@ -5057,6 +5057,7 @@ static void registerGeometryNodes()
   register_node_type_geo_is_viewport();
   register_node_type_geo_join_geometry();
   register_node_type_geo_material_assign();
+  register_node_type_geo_material_replace();
   register_node_type_geo_mesh_primitive_circle();
   register_node_type_geo_mesh_primitive_cone();
   register_node_type_geo_mesh_primitive_cube();

source/blender/nodes/CMakeLists.txt

@@ -169,6 +169,7 @@ set(SRC
   geometry/nodes/node_geo_is_viewport.cc
   geometry/nodes/node_geo_join_geometry.cc
   geometry/nodes/node_geo_material_assign.cc
+  geometry/nodes/node_geo_material_replace.cc
   geometry/nodes/node_geo_mesh_primitive_circle.cc
   geometry/nodes/node_geo_mesh_primitive_cone.cc
   geometry/nodes/node_geo_mesh_primitive_cube.cc

source/blender/nodes/NOD_geometry.h

@@ -57,6 +57,7 @@ void register_node_type_geo_input_material(void);
 void register_node_type_geo_is_viewport(void);
 void register_node_type_geo_join_geometry(void);
 void register_node_type_geo_material_assign(void);
+void register_node_type_geo_material_replace(void);
 void register_node_type_geo_mesh_primitive_circle(void);
 void register_node_type_geo_mesh_primitive_cone(void);
 void register_node_type_geo_mesh_primitive_cube(void);

source/blender/nodes/NOD_static_types.h

@@ -296,6 +296,7 @@ DefNode(GeometryNode, GEO_NODE_INPUT_MATERIAL, def_geo_input_material, "INPUT_MA
 DefNode(GeometryNode, GEO_NODE_IS_VIEWPORT, 0, "IS_VIEWPORT", IsViewport, "Is Viewport", "")
 DefNode(GeometryNode, GEO_NODE_JOIN_GEOMETRY, 0, "JOIN_GEOMETRY", JoinGeometry, "Join Geometry", "")
 DefNode(GeometryNode, GEO_NODE_MATERIAL_ASSIGN, 0, "MATERIAL_ASSIGN", MaterialAssign, "Material Assign", "")
+DefNode(GeometryNode, GEO_NODE_MATERIAL_REPLACE, 0, "MATERIAL_REPLACE", MaterialReplace, "Material Replace", "")
 DefNode(GeometryNode, GEO_NODE_MESH_PRIMITIVE_CIRCLE, def_geo_mesh_circle, "MESH_PRIMITIVE_CIRCLE", MeshCircle, "Circle", "")
 DefNode(GeometryNode, GEO_NODE_MESH_PRIMITIVE_CONE, def_geo_mesh_cone, "MESH_PRIMITIVE_CONE", MeshCone, "Cone", "")
 DefNode(GeometryNode, GEO_NODE_MESH_PRIMITIVE_CUBE, 0, "MESH_PRIMITIVE_CUBE", MeshCube, "Cube", "")

source/blender/nodes/geometry/nodes/node_geo_material_replace.cc

@@ -0,0 +1,75 @@
+/*
+ * 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"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "BKE_material.h"
+
+static bNodeSocketTemplate geo_node_material_replace_in[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {SOCK_MATERIAL, N_("Old")},
+    {SOCK_MATERIAL, N_("New")},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_material_replace_out[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {-1, ""},
+};
+
+namespace blender::nodes {
+
+static void geo_node_material_replace_exec(GeoNodeExecParams params)
+{
+  Material *old_material = params.extract_input<Material *>("Old");
+  Material *new_material = params.extract_input<Material *>("New");
+
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Geometry");
+  geometry_set = geometry_set_realize_instances(geometry_set);
+
+  if (geometry_set.has<MeshComponent>()) {
+    MeshComponent &mesh_component = geometry_set.get_component_for_write<MeshComponent>();
+    Mesh *mesh = mesh_component.get_for_write();
+    if (mesh != nullptr) {
+      for (const int i : IndexRange(mesh->totcol)) {
+        if (mesh->mat[i] == old_material) {
+          mesh->mat[i] = new_material;
+        }
+      }
+    }
+  }
+
+  params.set_output("Geometry", std::move(geometry_set));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_material_replace()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(
+      &ntype, GEO_NODE_MATERIAL_REPLACE, "Material Replace", NODE_CLASS_GEOMETRY, 0);
+  node_type_socket_templates(&ntype, geo_node_material_replace_in, geo_node_material_replace_out);
+  ntype.geometry_node_execute = blender::nodes::geo_node_material_replace_exec;
+  nodeRegisterType(&ntype);
+}