1 files changed, 98 insertions, 0 deletions
diff --git a/source/blender/nodes/geometry/nodes/node_geo_material_assign.cc b/source/blender/nodes/geometry/nodes/node_geo_material_assign.cc
new file mode 100644
index 00000000000..8c245afd3d2
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_material_assign.cc
@@ -0,0 +1,98 @@
+/*
+ * 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_assign_in[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {SOCK_MATERIAL, N_("Material")},
+    {SOCK_STRING, N_("Selection")},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_material_assign_out[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {-1, ""},
+};
+
+namespace blender::nodes {
+
+static void assign_material_to_faces(Mesh &mesh, const VArray<bool> &face_mask, Material *material)
+{
+  int new_material_index = -1;
+  for (const int i : IndexRange(mesh.totcol)) {
+    Material *other_material = mesh.mat[i];
+    if (other_material == material) {
+      new_material_index = i;
+      break;
+    }
+  }
+  if (new_material_index == -1) {
+    /* Append a new material index. */
+    new_material_index = mesh.totcol;
+    BKE_id_material_eval_assign(&mesh.id, new_material_index + 1, material);
+  }
+
+  mesh.mpoly = (MPoly *)CustomData_duplicate_referenced_layer(&mesh.pdata, CD_MPOLY, mesh.totpoly);
+  for (const int i : IndexRange(mesh.totpoly)) {
+    if (face_mask[i]) {
+      MPoly &poly = mesh.mpoly[i];
+      poly.mat_nr = new_material_index;
+    }
+  }
+}
+
+static void geo_node_material_assign_exec(GeoNodeExecParams params)
+{
+  Material *material = params.extract_input<Material *>("Material");
+  const std::string mask_name = params.extract_input<std::string>("Selection");
+
+  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) {
+      GVArray_Typed<bool> face_mask = mesh_component.attribute_get_for_read<bool>(
+          mask_name, ATTR_DOMAIN_FACE, true);
+      assign_material_to_faces(*mesh, face_mask, material);
+    }
+  }
+
+  params.set_output("Geometry", std::move(geometry_set));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_material_assign()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_MATERIAL_ASSIGN, "Material Assign", NODE_CLASS_GEOMETRY, 0);
+  node_type_socket_templates(&ntype, geo_node_material_assign_in, geo_node_material_assign_out);
+  ntype.geometry_node_execute = blender::nodes::geo_node_material_assign_exec;
+  nodeRegisterType(&ntype);
+}