Subdivision Surfaces: add boundary smooth option to modifiers

This adds the option to either smooth the entire boundary, or to keep
corners sharp, for the Subdivision Surface and Multiresolution modifiers.

This mainly helps with compatibility with other software. The default
behavior remains to smooth the entire boundary.

Differential Revision: https://developer.blender.org/D8485

2 files changed, 6 insertions, 1 deletions

diff --git a/source/blender/modifiers/intern/MOD_multires.c b/source/blender/modifiers/intern/MOD_multires.c
index 2c6ee50d419..41188fcc907 100644
--- a/source/blender/modifiers/intern/MOD_multires.c
+++ b/source/blender/modifiers/intern/MOD_multires.c
@@ -73,6 +73,7 @@ static void initData(ModifierData *md)
   mmd->renderlvl = 0;
   mmd->totlvl = 0;
   mmd->uv_smooth = SUBSURF_UV_SMOOTH_PRESERVE_CORNERS;
+  mmd->boundary_smooth = SUBSURF_BOUNDARY_SMOOTH_ALL;
   mmd->quality = 4;
   mmd->flags |= (eMultiresModifierFlag_UseCrease | eMultiresModifierFlag_ControlEdges);
 
@@ -489,6 +490,7 @@ static void advanced_panel_draw(const bContext *UNUSED(C), Panel *panel)
   col = uiLayoutColumn(layout, false);
   uiLayoutSetEnabled(col, true);
   uiItemR(col, ptr, "uv_smooth", 0, NULL, ICON_NONE);
+  uiItemR(col, ptr, "boundary_smooth", 0, NULL, ICON_NONE);
 
   uiItemR(layout, ptr, "use_creases", 0, NULL, ICON_NONE);
   uiItemR(layout, ptr, "use_custom_normals", 0, NULL, ICON_NONE);
diff --git a/source/blender/modifiers/intern/MOD_subsurf.c b/source/blender/modifiers/intern/MOD_subsurf.c
index 7a118c6c14d..10d7b21d56f 100644
--- a/source/blender/modifiers/intern/MOD_subsurf.c
+++ b/source/blender/modifiers/intern/MOD_subsurf.c
@@ -74,6 +74,7 @@ static void initData(ModifierData *md)
   smd->levels = 1;
   smd->renderLevels = 2;
   smd->uv_smooth = SUBSURF_UV_SMOOTH_PRESERVE_CORNERS;
+  smd->boundary_smooth = SUBSURF_BOUNDARY_SMOOTH_ALL;
   smd->quality = 3;
   smd->flags |= (eSubsurfModifierFlag_UseCrease | eSubsurfModifierFlag_ControlEdges);
 }
@@ -167,7 +168,8 @@ static void subdiv_settings_init(SubdivSettings *settings,
                         1 :
                         (settings->is_adaptive ? smd->quality : requested_levels);
   settings->use_creases = (smd->flags & eSubsurfModifierFlag_UseCrease);
-  settings->vtx_boundary_interpolation = SUBDIV_VTX_BOUNDARY_EDGE_ONLY;
+  settings->vtx_boundary_interpolation = BKE_subdiv_vtx_boundary_interpolation_from_subsurf(
+      smd->boundary_smooth);
   settings->fvar_linear_interpolation = BKE_subdiv_fvar_interpolation_from_uv_smooth(
       smd->uv_smooth);
 }
@@ -471,6 +473,7 @@ static void advanced_panel_draw(const bContext *C, Panel *panel)
   uiItemR(col, ptr, "quality", 0, NULL, ICON_NONE);
 
   uiItemR(layout, ptr, "uv_smooth", 0, NULL, ICON_NONE);
+  uiItemR(layout, ptr, "boundary_smooth", 0, NULL, ICON_NONE);
   uiItemR(layout, ptr, "use_creases", 0, NULL, ICON_NONE);
   uiItemR(layout, ptr, "use_custom_normals", 0, NULL, ICON_NONE);
 }