Multires: Remove simple subdivision type

The simple subdivision as a type only causes issues like no-continuous
normals across edges, inability to reliably switch the type and things
like this.

The new subdivision operators supports wider variety of how to add
details to the model, which are more powerful than a single one-time
decision on the subdivision type.

The versioning code is adjusting topology converter to specify all
edges as infinitely sharp. The reason for this (instead of using
settings.is_simple) is because in a longer term the simple subdivision
will be removed from Subsurf modifier as well, and will be replaced
with more efficient bmesh-based modifier.

This is finished up version of D8436.

Differential Revision: https://developer.blender.org/D9350

6 files changed, 137 insertions, 22 deletions

diff --git a/source/blender/blenkernel/intern/multires.c b/source/blender/blenkernel/intern/multires.c
index d7ea662a5d6..441da8b134a 100644
--- a/source/blender/blenkernel/intern/multires.c
+++ b/source/blender/blenkernel/intern/multires.c
@@ -747,7 +747,6 @@ static DerivedMesh *multires_dm_create_local(Scene *scene,
                                              DerivedMesh *dm,
                                              int lvl,
                                              int totlvl,
-                                             int simple,
                                              bool alloc_paint_mask,
                                              int flags)
 {
@@ -757,7 +756,6 @@ static DerivedMesh *multires_dm_create_local(Scene *scene,
   mmd.sculptlvl = lvl;
   mmd.renderlvl = lvl;
   mmd.totlvl = totlvl;
-  mmd.simple = simple;
 
   flags |= MULTIRES_USE_LOCAL_MMD;
   if (alloc_paint_mask) {
@@ -1081,7 +1079,7 @@ void multires_modifier_update_mdisps(struct DerivedMesh *dm, Scene *scene)
                                        ob,
                                        cddm,
                                        totlvl,
-                                       mmd->simple,
+                                       false,
                                        0,
                                        mmd->uv_smooth == SUBSURF_UV_SMOOTH_NONE,
                                        has_mask,
@@ -1091,7 +1089,7 @@ void multires_modifier_update_mdisps(struct DerivedMesh *dm, Scene *scene)
 
       /* create multires DM from original mesh and displacements */
       lowdm = multires_dm_create_local(
-          scene, ob, cddm, lvl, totlvl, mmd->simple, has_mask, MULTIRES_IGNORE_SIMPLIFY);
+          scene, ob, cddm, lvl, totlvl, has_mask, MULTIRES_IGNORE_SIMPLIFY);
       cddm->release(cddm);
 
       /* gather grid data */
@@ -1156,7 +1154,7 @@ void multires_modifier_update_mdisps(struct DerivedMesh *dm, Scene *scene)
                                       ob,
                                       cddm,
                                       mmd->totlvl,
-                                      mmd->simple,
+                                      false,
                                       0,
                                       mmd->uv_smooth == SUBSURF_UV_SMOOTH_NONE,
                                       has_mask,
@@ -1254,7 +1252,7 @@ DerivedMesh *multires_make_derived_from_derived(
                                    ob,
                                    dm,
                                    lvl,
-                                   mmd->simple,
+                                   false,
                                    mmd->flags & eMultiresModifierFlag_ControlEdges,
                                    mmd->uv_smooth == SUBSURF_UV_SMOOTH_NONE,
                                    flags & MULTIRES_ALLOC_PAINT_MASK,
@@ -1368,14 +1366,8 @@ void multiresModifier_sync_levels_ex(Object *ob_dst,
   }
 
   if (mmd_src->totlvl > mmd_dst->totlvl) {
-    if (mmd_dst->simple) {
-      multiresModifier_subdivide_to_level(
-          ob_dst, mmd_dst, mmd_src->totlvl, MULTIRES_SUBDIVIDE_SIMPLE);
-    }
-    else {
-      multiresModifier_subdivide_to_level(
-          ob_dst, mmd_dst, mmd_src->totlvl, MULTIRES_SUBDIVIDE_CATMULL_CLARK);
-    }
+    multiresModifier_subdivide_to_level(
+        ob_dst, mmd_dst, mmd_src->totlvl, MULTIRES_SUBDIVIDE_CATMULL_CLARK);
   }
   else {
     multires_del_higher(mmd_dst, ob_dst, mmd_src->totlvl);
diff --git a/source/blender/blenkernel/intern/multires_reshape.h b/source/blender/blenkernel/intern/multires_reshape.h
index 9dec1423eba..36ecf1a6395 100644
--- a/source/blender/blenkernel/intern/multires_reshape.h
+++ b/source/blender/blenkernel/intern/multires_reshape.h
@@ -172,6 +172,12 @@ bool multires_reshape_context_create_from_modifier(MultiresReshapeContext *resha
                                                    struct MultiresModifierData *mmd,
                                                    int top_level);
 
+bool multires_reshape_context_create_from_subdiv(MultiresReshapeContext *reshape_context,
+                                                 struct Object *object,
+                                                 struct MultiresModifierData *mmd,
+                                                 struct Subdiv *subdiv,
+                                                 int top_level);
+
 void multires_reshape_free_original_grids(MultiresReshapeContext *reshape_context);
 void multires_reshape_context_free(MultiresReshapeContext *reshape_context);
 
diff --git a/source/blender/blenkernel/intern/multires_reshape_apply_base.c b/source/blender/blenkernel/intern/multires_reshape_apply_base.c
index 6e7e2b90c05..b693b1114ba 100644
--- a/source/blender/blenkernel/intern/multires_reshape_apply_base.c
+++ b/source/blender/blenkernel/intern/multires_reshape_apply_base.c
@@ -81,11 +81,6 @@ static float v3_dist_from_plane(const float v[3], const float center[3], const f
 
 void multires_reshape_apply_base_refit_base_mesh(MultiresReshapeContext *reshape_context)
 {
-  if (reshape_context->mmd->simple) {
-    /* Simple subdivisions does not move base mesh verticies, so no refitting is needed. */
-    return;
-  }
-
   Mesh *base_mesh = reshape_context->base_mesh;
 
   MeshElemMap *pmap;
diff --git a/source/blender/blenkernel/intern/multires_reshape_util.c b/source/blender/blenkernel/intern/multires_reshape_util.c
index f3b19961e29..8fb406e54a5 100644
--- a/source/blender/blenkernel/intern/multires_reshape_util.c
+++ b/source/blender/blenkernel/intern/multires_reshape_util.c
@@ -247,6 +247,22 @@ bool multires_reshape_context_create_from_modifier(MultiresReshapeContext *resha
                                                    struct MultiresModifierData *mmd,
                                                    int top_level)
 {
+  Subdiv *subdiv = multires_reshape_create_subdiv(NULL, object, mmd);
+
+  const bool result = multires_reshape_context_create_from_subdiv(
+      reshape_context, object, mmd, subdiv, top_level);
+
+  reshape_context->need_free_subdiv = true;
+
+  return result;
+}
+
+bool multires_reshape_context_create_from_subdiv(MultiresReshapeContext *reshape_context,
+                                                 struct Object *object,
+                                                 struct MultiresModifierData *mmd,
+                                                 struct Subdiv *subdiv,
+                                                 int top_level)
+{
   context_zero(reshape_context);
 
   Mesh *base_mesh = (Mesh *)object->data;
@@ -254,8 +270,8 @@ bool multires_reshape_context_create_from_modifier(MultiresReshapeContext *resha
   reshape_context->mmd = mmd;
   reshape_context->base_mesh = base_mesh;
 
-  reshape_context->subdiv = multires_reshape_create_subdiv(NULL, object, mmd);
-  reshape_context->need_free_subdiv = true;
+  reshape_context->subdiv = subdiv;
+  reshape_context->need_free_subdiv = false;
 
   reshape_context->reshape.level = mmd->totlvl;
   reshape_context->reshape.grid_size = BKE_subdiv_grid_size_from_level(
diff --git a/source/blender/blenkernel/intern/multires_subdiv.c b/source/blender/blenkernel/intern/multires_subdiv.c
index 73ef623fbfd..8156814d9f1 100644
--- a/source/blender/blenkernel/intern/multires_subdiv.c
+++ b/source/blender/blenkernel/intern/multires_subdiv.c
@@ -36,7 +36,7 @@
 
 void BKE_multires_subdiv_settings_init(SubdivSettings *settings, const MultiresModifierData *mmd)
 {
-  settings->is_simple = (mmd->simple != 0);
+  settings->is_simple = false;
   settings->is_adaptive = true;
   settings->level = settings->is_simple ? 1 : mmd->quality;
   settings->use_creases = (mmd->flags & eMultiresModifierFlag_UseCrease);
diff --git a/source/blender/blenkernel/intern/multires_versioning.c b/source/blender/blenkernel/intern/multires_versioning.c
new file mode 100644
index 00000000000..4c0d7165cd0
--- /dev/null
+++ b/source/blender/blenkernel/intern/multires_versioning.c
@@ -0,0 +1,106 @@
+/*
+ * 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) 2020 by Blender Foundation.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bke
+ */
+
+#include "MEM_guardedalloc.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_modifier_types.h"
+#include "DNA_object_types.h"
+
+#include "BKE_subdiv.h"
+#include "BKE_subdiv_eval.h"
+
+#include "multires_reshape.h"
+#include "opensubdiv_converter_capi.h"
+#include "subdiv_converter.h"
+
+static float simple_to_catmull_clark_get_edge_sharpness(
+    const OpenSubdiv_Converter *UNUSED(converter), int UNUSED(manifold_edge_index))
+{
+  return 10.0f;
+}
+
+static bool simple_to_catmull_clark_is_infinite_sharp_vertex(
+    const OpenSubdiv_Converter *UNUSED(converter), int UNUSED(manifold_vertex_index))
+{
+  return true;
+}
+
+static Subdiv *subdiv_for_simple_to_catmull_clark(Object *object, MultiresModifierData *mmd)
+{
+  SubdivSettings subdiv_settings;
+  BKE_multires_subdiv_settings_init(&subdiv_settings, mmd);
+
+  Mesh *base_mesh = object->data;
+
+  OpenSubdiv_Converter converter;
+  BKE_subdiv_converter_init_for_mesh(&converter, &subdiv_settings, base_mesh);
+  converter.getEdgeSharpness = simple_to_catmull_clark_get_edge_sharpness;
+  converter.isInfiniteSharpVertex = simple_to_catmull_clark_is_infinite_sharp_vertex;
+
+  Subdiv *subdiv = BKE_subdiv_new_from_converter(&subdiv_settings, &converter);
+  BKE_subdiv_converter_free(&converter);
+
+  if (!BKE_subdiv_eval_begin_from_mesh(subdiv, base_mesh, NULL)) {
+    BKE_subdiv_free(subdiv);
+    return NULL;
+  }
+
+  return subdiv;
+}
+
+void multires_do_versions_simple_to_catmull_clark(Object *object, MultiresModifierData *mmd)
+{
+  const Mesh *base_mesh = object->data;
+  if (base_mesh->totloop == 0) {
+    return;
+  }
+
+  /* Store the grids displacement in object space against the simple limit surface. */
+  {
+    Subdiv *subdiv = subdiv_for_simple_to_catmull_clark(object, mmd);
+    MultiresReshapeContext reshape_context;
+    if (!multires_reshape_context_create_from_subdiv(
+            &reshape_context, object, mmd, subdiv, mmd->totlvl)) {
+      BKE_subdiv_free(subdiv);
+      return;
+    }
+
+    multires_reshape_store_original_grids(&reshape_context);
+    multires_reshape_assign_final_coords_from_mdisps(&reshape_context);
+    multires_reshape_context_free(&reshape_context);
+
+    BKE_subdiv_free(subdiv);
+  }
+
+  /* Calculate the new tangent displacement against the new Catmull-Clark limit surface. */
+  {
+    MultiresReshapeContext reshape_context;
+    if (!multires_reshape_context_create_from_modifier(
+            &reshape_context, object, mmd, mmd->totlvl)) {
+      return;
+    }
+    multires_reshape_object_grids_to_tangent_displacement(&reshape_context);
+    multires_reshape_context_free(&reshape_context);
+  }
+}