OpenVDB: Voxel Remesher

The voxel remesher introduces a new workflow for sculpting without any of the limitations of Dyntopo (no geometry errors or performance penalty when blocking shapes). It is also useful for simulations and 3D printing.

This commit includes:
- Voxel remesh operator, voxel size mesh property and general remesh flags.
- Paint mask reprojection.
- Geometry undo/redo for sculpt mode. This should support remesh operations as well as future tools that modify the topology of the sculpt in a single step, like trimming tools or mesh insert brushes.
- UI changes in the sculpt topbar and the mesh properties pannel.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5407

4 files changed, 165 insertions, 0 deletions

diff --git a/source/blender/editors/object/CMakeLists.txt b/source/blender/editors/object/CMakeLists.txt
index eaef9313431..2490f88b5eb 100644
--- a/source/blender/editors/object/CMakeLists.txt
+++ b/source/blender/editors/object/CMakeLists.txt
@@ -57,6 +57,7 @@ set(SRC
   object_ops.c
   object_random.c
   object_relations.c
+  object_remesh.c
   object_select.c
   object_shader_fx.c
   object_shapekey.c
diff --git a/source/blender/editors/object/object_intern.h b/source/blender/editors/object/object_intern.h
index e697c25b37f..4b369c10e4d 100644
--- a/source/blender/editors/object/object_intern.h
+++ b/source/blender/editors/object/object_intern.h
@@ -279,6 +279,9 @@ void OBJECT_OT_bake(wmOperatorType *ot);
 /* object_random.c */
 void TRANSFORM_OT_vertex_random(struct wmOperatorType *ot);
 
+/* object_remesh.c */
+void OBJECT_OT_voxel_remesh(struct wmOperatorType *ot);
+
 /* object_transfer_data.c */
 void OBJECT_OT_data_transfer(struct wmOperatorType *ot);
 void OBJECT_OT_datalayout_transfer(struct wmOperatorType *ot);
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index b653c7fa70c..38c06319450 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -257,6 +257,8 @@ void ED_operatortypes_object(void)
   WM_operatortype_append(OBJECT_OT_hide_view_clear);
   WM_operatortype_append(OBJECT_OT_hide_view_set);
   WM_operatortype_append(OBJECT_OT_hide_collection);
+
+  WM_operatortype_append(OBJECT_OT_voxel_remesh);
 }
 
 void ED_operatormacros_object(void)
diff --git a/source/blender/editors/object/object_remesh.c b/source/blender/editors/object/object_remesh.c
new file mode 100644
index 00000000000..a7e7256757d
--- /dev/null
+++ b/source/blender/editors/object/object_remesh.c
@@ -0,0 +1,159 @@
+/*
+ * 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.
+ *
+ * The Original Code is Copyright (C) 2019 by Blender Foundation
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup edobj
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <float.h>
+#include <ctype.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_blenlib.h"
+#include "BLI_math.h"
+#include "BLI_utildefines.h"
+
+#include "DNA_scene_types.h"
+#include "DNA_object_types.h"
+#include "DNA_meshdata_types.h"
+#include "DNA_mesh_types.h"
+
+#include "BKE_context.h"
+#include "BKE_global.h"
+#include "BKE_main.h"
+#include "BKE_mesh.h"
+#include "BKE_object.h"
+#include "BKE_paint.h"
+#include "BKE_report.h"
+#include "BKE_scene.h"
+#include "BKE_customdata.h"
+#include "BKE_remesh.h"
+
+#include "DEG_depsgraph.h"
+#include "DEG_depsgraph_build.h"
+
+#include "ED_mesh.h"
+#include "ED_object.h"
+#include "ED_screen.h"
+#include "ED_sculpt.h"
+#include "ED_undo.h"
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+#include "RNA_enum_types.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+#include "WM_message.h"
+#include "WM_toolsystem.h"
+
+#include "object_intern.h"  // own include
+
+static bool object_remesh_poll(bContext *C)
+{
+  Object *ob = CTX_data_active_object(C);
+
+  if (BKE_object_is_in_editmode(ob)) {
+    CTX_wm_operator_poll_msg_set(C, "The voxel remesher cannot run from edit mode.");
+    return false;
+  }
+
+  if (ob->mode == OB_MODE_SCULPT && ob->sculpt->bm) {
+    CTX_wm_operator_poll_msg_set(C, "The voxel remesher cannot run with dyntopo activated.");
+  }
+
+  return ED_operator_object_active_editable_mesh(C);
+}
+
+static int voxel_remesh_exec(bContext *C, wmOperator *op)
+{
+  Object *ob = CTX_data_active_object(C);
+  Main *bmain = CTX_data_main(C);
+
+  Mesh *mesh = ob->data;
+  Mesh *new_mesh;
+
+  if (mesh->remesh_voxel_size <= 0.0f) {
+    BKE_report(op->reports, RPT_ERROR, "Voxel remesher cannot run with a voxel size of 0.0.");
+    return OPERATOR_CANCELLED;
+  }
+
+  if (ob->mode == OB_MODE_SCULPT) {
+    ED_sculpt_undo_geometry_begin(ob);
+  }
+
+  new_mesh = BKE_remesh_voxel_to_mesh_nomain(mesh, mesh->remesh_voxel_size);
+
+  if (!new_mesh) {
+    return OPERATOR_CANCELLED;
+  }
+
+  Mesh *obj_mesh_copy;
+  if (mesh->flag & ME_REMESH_REPROJECT_PAINT_MASK) {
+    obj_mesh_copy = BKE_mesh_new_nomain_from_template(mesh, mesh->totvert, 0, 0, 0, 0);
+    CustomData_copy(
+        &mesh->vdata, &obj_mesh_copy->vdata, CD_MASK_MESH.vmask, CD_DUPLICATE, mesh->totvert);
+    for (int i = 0; i < mesh->totvert; i++) {
+      copy_v3_v3(obj_mesh_copy->mvert[i].co, mesh->mvert[i].co);
+    }
+  }
+
+  BKE_mesh_nomain_to_mesh(new_mesh, mesh, ob, &CD_MASK_MESH, true);
+  BKE_mesh_free(new_mesh);
+
+  if (mesh->flag & ME_REMESH_REPROJECT_PAINT_MASK) {
+    BKE_remesh_reproject_paint_mask(mesh, obj_mesh_copy);
+    BKE_mesh_free(obj_mesh_copy);
+  }
+
+  if (mesh->flag & ME_REMESH_SMOOTH_NORMALS) {
+    BKE_mesh_smooth_flag_set(ob, true);
+  }
+
+  if (ob->mode == OB_MODE_SCULPT) {
+    ED_sculpt_undo_geometry_end(ob);
+  }
+
+  BKE_mesh_batch_cache_dirty_tag(ob->data, BKE_MESH_BATCH_DIRTY_ALL);
+  DEG_relations_tag_update(bmain);
+  DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_GEOM | ND_DATA, ob->data);
+
+  return OPERATOR_FINISHED;
+}
+
+void OBJECT_OT_voxel_remesh(wmOperatorType *ot)
+{
+  /* identifiers */
+  ot->name = "Voxel Remesh";
+  ot->description =
+      "Calculates a new manifold mesh based on the volume of the current mesh. All data layers "
+      "will be lost";
+  ot->idname = "OBJECT_OT_voxel_remesh";
+
+  /* api callbacks */
+  ot->poll = object_remesh_poll;
+  ot->exec = voxel_remesh_exec;
+
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+}