Multires: Fix Subdivide, Reshape and Apply Base

This change fixes artifacts produced by these operations.

On a technical aspect this is done by porting all of the operations
to the new subdivision surface implementation which ensures that
tangent space used to evaluate modifier and those operations is
exactly the same (before modifier will use new code and the operations
will still use an old one).

The next step is to get sculpting on a non-top level to work, and
that actually requires fixes in the undo system.

1 files changed, 210 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/multires_reshape_vertcos.c b/source/blender/blenkernel/intern/multires_reshape_vertcos.c
new file mode 100644
index 00000000000..c47b50faa03
--- /dev/null
+++ b/source/blender/blenkernel/intern/multires_reshape_vertcos.c
@@ -0,0 +1,210 @@
+/*
+ * 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 Blender Foundation.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bke
+ */
+
+#include "multires_reshape.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "BLI_math_vector.h"
+
+#include "BKE_subdiv_foreach.h"
+#include "BKE_subdiv_mesh.h"
+
+typedef struct MultiresReshapeAssignVertcosContext {
+  const MultiresReshapeContext *reshape_context;
+
+  const float (*vert_coords)[3];
+  const int num_vert_coords;
+} MultiresReshapeAssignVertcosContext;
+
+/* Set single displacement grid value at a reshape level to a correspnding vertex coordinate.
+ * This function will be called for every side of a boundary grid points for inner coordinates. */
+static void multires_reshape_vertcos_foreach_single_vertex(
+    const SubdivForeachContext *foreach_context,
+    const GridCoord *grid_coord,
+    const int subdiv_vertex_index)
+{
+  MultiresReshapeAssignVertcosContext *reshape_vertcos_context = foreach_context->user_data;
+  const float *coordinate = reshape_vertcos_context->vert_coords[subdiv_vertex_index];
+
+  ReshapeGridElement grid_element = multires_reshape_grid_element_for_grid_coord(
+      reshape_vertcos_context->reshape_context, grid_coord);
+  BLI_assert(grid_element.displacement != NULL);
+  copy_v3_v3(grid_element.displacement, coordinate);
+}
+
+/* TODO(sergey): De-duplicate with similar function in multires_reshape_smooth.c */
+static void multires_reshape_vertcos_foreach_vertex(const SubdivForeachContext *foreach_context,
+                                                    const PTexCoord *ptex_coord,
+                                                    const int subdiv_vertex_index)
+{
+  const MultiresReshapeAssignVertcosContext *reshape_vertcos_context = foreach_context->user_data;
+  const MultiresReshapeContext *reshape_context = reshape_vertcos_context->reshape_context;
+
+  const GridCoord grid_coord = multires_reshape_ptex_coord_to_grid(reshape_context, ptex_coord);
+  const int face_index = multires_reshape_grid_to_face_index(reshape_context,
+                                                             grid_coord.grid_index);
+
+  const Mesh *base_mesh = reshape_context->base_mesh;
+  const MPoly *base_poly = &base_mesh->mpoly[face_index];
+  const int num_corners = base_poly->totloop;
+  const int start_grid_index = reshape_context->face_start_grid_index[face_index];
+  const int corner = grid_coord.grid_index - start_grid_index;
+
+  if (grid_coord.u == 0.0f && grid_coord.v == 0.0f) {
+    for (int current_corner = 0; current_corner < num_corners; ++current_corner) {
+      GridCoord corner_grid_coord = grid_coord;
+      corner_grid_coord.grid_index = start_grid_index + current_corner;
+      multires_reshape_vertcos_foreach_single_vertex(
+          foreach_context, &corner_grid_coord, subdiv_vertex_index);
+    }
+    return;
+  }
+
+  multires_reshape_vertcos_foreach_single_vertex(
+      foreach_context, &grid_coord, subdiv_vertex_index);
+
+  if (grid_coord.u == 0.0f) {
+    GridCoord prev_grid_coord;
+    prev_grid_coord.grid_index = start_grid_index + ((corner + num_corners - 1) % num_corners);
+    prev_grid_coord.u = grid_coord.v;
+    prev_grid_coord.v = 0.0f;
+
+    multires_reshape_vertcos_foreach_single_vertex(
+        foreach_context, &prev_grid_coord, subdiv_vertex_index);
+  }
+
+  if (grid_coord.v == 0.0f) {
+    GridCoord next_grid_coord;
+    next_grid_coord.grid_index = start_grid_index + ((corner + 1) % num_corners);
+    next_grid_coord.u = 0.0f;
+    next_grid_coord.v = grid_coord.u;
+
+    multires_reshape_vertcos_foreach_single_vertex(
+        foreach_context, &next_grid_coord, subdiv_vertex_index);
+  }
+}
+
+/* SubdivForeachContext::topology_info() */
+static bool multires_reshape_vertcos_foreach_topology_info(
+    const SubdivForeachContext *foreach_context,
+    const int num_vertices,
+    const int UNUSED(num_edges),
+    const int UNUSED(num_loops),
+    const int UNUSED(num_polygons))
+{
+  MultiresReshapeAssignVertcosContext *reshape_vertcos_context = foreach_context->user_data;
+  if (num_vertices != reshape_vertcos_context->num_vert_coords) {
+    return false;
+  }
+  return true;
+}
+
+/* SubdivForeachContext::vertex_inner() */
+static void multires_reshape_vertcos_foreach_vertex_inner(
+    const SubdivForeachContext *foreach_context,
+    void *UNUSED(tls_v),
+    const int ptex_face_index,
+    const float ptex_face_u,
+    const float ptex_face_v,
+    const int UNUSED(coarse_face_index),
+    const int UNUSED(coarse_face_corner),
+    const int subdiv_vertex_index)
+{
+  const PTexCoord ptex_coord = {
+      .ptex_face_index = ptex_face_index,
+      .u = ptex_face_u,
+      .v = ptex_face_v,
+  };
+  multires_reshape_vertcos_foreach_vertex(foreach_context, &ptex_coord, subdiv_vertex_index);
+}
+
+/* SubdivForeachContext::vertex_every_corner() */
+static void multires_reshape_vertcos_foreach_vertex_every_corner(
+    const struct SubdivForeachContext *foreach_context,
+    void *UNUSED(tls_v),
+    const int ptex_face_index,
+    const float ptex_face_u,
+    const float ptex_face_v,
+    const int UNUSED(coarse_vertex_index),
+    const int UNUSED(coarse_face_index),
+    const int UNUSED(coarse_face_corner),
+    const int subdiv_vertex_index)
+{
+  const PTexCoord ptex_coord = {
+      .ptex_face_index = ptex_face_index,
+      .u = ptex_face_u,
+      .v = ptex_face_v,
+  };
+  multires_reshape_vertcos_foreach_vertex(foreach_context, &ptex_coord, subdiv_vertex_index);
+}
+
+/* SubdivForeachContext::vertex_every_edge() */
+static void multires_reshape_vertcos_foreach_vertex_every_edge(
+    const struct SubdivForeachContext *foreach_context,
+    void *UNUSED(tls_v),
+    const int ptex_face_index,
+    const float ptex_face_u,
+    const float ptex_face_v,
+    const int UNUSED(coarse_edge_index),
+    const int UNUSED(coarse_face_index),
+    const int UNUSED(coarse_face_corner),
+    const int subdiv_vertex_index)
+{
+  const PTexCoord ptex_coord = {
+      .ptex_face_index = ptex_face_index,
+      .u = ptex_face_u,
+      .v = ptex_face_v,
+  };
+  multires_reshape_vertcos_foreach_vertex(foreach_context, &ptex_coord, subdiv_vertex_index);
+}
+
+/* Set displacement grids values at a reshape level to a object coordinates of the the given
+ * source. */
+bool multires_reshape_assign_final_coords_from_vertcos(
+    const MultiresReshapeContext *reshape_context,
+    const float (*vert_coords)[3],
+    const int num_vert_coords)
+{
+  MultiresReshapeAssignVertcosContext reshape_vertcos_context = {
+      .reshape_context = reshape_context,
+      .vert_coords = vert_coords,
+      .num_vert_coords = num_vert_coords,
+  };
+
+  SubdivForeachContext foreach_context = {
+      .topology_info = multires_reshape_vertcos_foreach_topology_info,
+      .vertex_inner = multires_reshape_vertcos_foreach_vertex_inner,
+      .vertex_every_edge = multires_reshape_vertcos_foreach_vertex_every_edge,
+      .vertex_every_corner = multires_reshape_vertcos_foreach_vertex_every_corner,
+      .user_data = &reshape_vertcos_context,
+  };
+
+  SubdivToMeshSettings mesh_settings;
+  mesh_settings.resolution = (1 << reshape_context->reshape.level) + 1;
+  mesh_settings.use_optimal_display = false;
+
+  return BKE_subdiv_foreach_subdiv_geometry(
+      reshape_context->subdiv, &foreach_context, &mesh_settings, reshape_context->base_mesh);
+}