Geometry Nodes: Triangulate Node - Add Selection Input

This adds a selection field input to the node, faces that are selected and
meet the minimum vertex count threshold will be triangulated.

Differential Revision: https://developer.blender.org/D13804

1 files changed, 50 insertions, 13 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_triangulate.cc b/source/blender/nodes/geometry/nodes/node_geo_triangulate.cc
index 998e4d58bf3..e78c4d7bc35 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_triangulate.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_triangulate.cc
@@ -14,24 +14,25 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "BKE_customdata.h"
+#include "BKE_mesh.h"
+
+#include "bmesh.h"
+#include "bmesh_tools.h"
+
+#include "DNA_mesh_types.h"
+
 #include "UI_interface.h"
 #include "UI_resources.h"
 
 #include "node_geometry_util.hh"
 
-extern "C" {
-Mesh *triangulate_mesh(Mesh *mesh,
-                       const int quad_method,
-                       const int ngon_method,
-                       const int min_vertices,
-                       const int flag);
-}
-
 namespace blender::nodes::node_geo_triangulate_cc {
 
 static void node_declare(NodeDeclarationBuilder &b)
 {
   b.add_input<decl::Geometry>(N_("Mesh")).supported_type(GEO_COMPONENT_TYPE_MESH);
+  b.add_input<decl::Bool>(N_("Selection")).default_value(true).supports_field().hide_value();
   b.add_input<decl::Int>(N_("Minimum Vertices")).default_value(4).min(4).max(10000);
   b.add_output<decl::Geometry>(N_("Mesh"));
 }
@@ -48,9 +49,35 @@ static void geo_triangulate_init(bNodeTree *UNUSED(ntree), bNode *node)
   node->custom2 = GEO_NODE_TRIANGULATE_NGON_BEAUTY;
 }
 
+static Mesh *triangulate_mesh_selection(const Mesh &mesh,
+                                        const int quad_method,
+                                        const int ngon_method,
+                                        const IndexMask selection,
+                                        const int min_vertices)
+{
+  CustomData_MeshMasks cd_mask_extra = {
+      CD_MASK_ORIGINDEX, CD_MASK_ORIGINDEX, 0, CD_MASK_ORIGINDEX};
+  BMeshCreateParams create_params{0};
+  BMeshFromMeshParams from_mesh_params{true, 1, 1, 1, cd_mask_extra};
+  BMesh *bm = BKE_mesh_to_bmesh_ex(&mesh, &create_params, &from_mesh_params);
+
+  /* Tag faces to be triangulated from the selection mask. */
+  BM_mesh_elem_table_ensure(bm, BM_FACE);
+  for (int i_face : selection) {
+    BM_elem_flag_set(BM_face_at_index(bm, i_face), BM_ELEM_TAG, true);
+  }
+
+  BM_mesh_triangulate(bm, quad_method, ngon_method, min_vertices, true, NULL, NULL, NULL);
+  Mesh *result = BKE_mesh_from_bmesh_for_eval_nomain(bm, &cd_mask_extra, &mesh);
+  BM_mesh_free(bm);
+  BKE_mesh_normals_tag_dirty(result);
+  return result;
+}
+
 static void node_geo_exec(GeoNodeExecParams params)
 {
   GeometrySet geometry_set = params.extract_input<GeometrySet>("Mesh");
+  Field<bool> selection_field = params.extract_input<Field<bool>>("Selection");
   const int min_vertices = std::max(params.extract_input<int>("Minimum Vertices"), 4);
 
   GeometryNodeTriangulateQuads quad_method = static_cast<GeometryNodeTriangulateQuads>(
@@ -59,12 +86,22 @@ static void node_geo_exec(GeoNodeExecParams params)
       params.node().custom2);
 
   geometry_set.modify_geometry_sets([&](GeometrySet &geometry_set) {
-    /* #triangulate_mesh might modify the input mesh currently. */
-    Mesh *mesh_in = geometry_set.get_mesh_for_write();
-    if (mesh_in != nullptr) {
-      Mesh *mesh_out = triangulate_mesh(mesh_in, quad_method, ngon_method, min_vertices, 0);
-      geometry_set.replace_mesh(mesh_out);
+    if (!geometry_set.has_mesh()) {
+      return;
     }
+    GeometryComponent &component = geometry_set.get_component_for_write<MeshComponent>();
+    const Mesh &mesh_in = *geometry_set.get_mesh_for_read();
+
+    const int domain_size = component.attribute_domain_size(ATTR_DOMAIN_FACE);
+    GeometryComponentFieldContext context{component, ATTR_DOMAIN_FACE};
+    FieldEvaluator evaluator{context, domain_size};
+    evaluator.add(selection_field);
+    evaluator.evaluate();
+    const IndexMask selection = evaluator.get_evaluated_as_mask(0);
+
+    Mesh *mesh_out = triangulate_mesh_selection(
+        mesh_in, quad_method, ngon_method, selection, min_vertices);
+    geometry_set.replace_mesh(mesh_out);
   });
 
   params.set_output("Mesh", std::move(geometry_set));