Subdiv: Add vertex deformation callback to multires/subsurf

Currently unused but the intention is to use this to hook up these
modifiers to a generic deformed PBVH to make it easier to sculpt or
paint on a subdivided mesh.

1 files changed, 32 insertions, 1 deletions

diff --git a/source/blender/modifiers/intern/MOD_multires.c b/source/blender/modifiers/intern/MOD_multires.c
index dd7c001931c..53bb579128a 100644
--- a/source/blender/modifiers/intern/MOD_multires.c
+++ b/source/blender/modifiers/intern/MOD_multires.c
@@ -38,6 +38,7 @@
 #include "BKE_paint.h"
 #include "BKE_subdiv.h"
 #include "BKE_subdiv_ccg.h"
+#include "BKE_subdiv_deform.h"
 #include "BKE_subdiv_mesh.h"
 #include "BKE_subsurf.h"
 
@@ -227,6 +228,36 @@ static Mesh *applyModifier(ModifierData *md, const ModifierEvalContext *ctx, Mes
   return result;
 }
 
+static void deformVerts(ModifierData *md,
+                        const ModifierEvalContext *UNUSED(ctx),
+                        Mesh *mesh,
+                        float (*vertex_cos)[3],
+                        int num_verts)
+{
+#if !defined(WITH_OPENSUBDIV)
+  modifier_setError(md, "Disabled, built without OpenSubdiv");
+  return;
+#endif
+  MultiresModifierData *mmd = (MultiresModifierData *)md;
+  SubdivSettings subdiv_settings;
+  BKE_multires_subdiv_settings_init(&subdiv_settings, mmd);
+  if (subdiv_settings.level == 0) {
+    return;
+  }
+  BKE_subdiv_settings_validate_for_mesh(&subdiv_settings, mesh);
+  MultiresRuntimeData *runtime_data = multires_ensure_runtime(mmd);
+  Subdiv *subdiv = subdiv_descriptor_ensure(mmd, &subdiv_settings, mesh);
+  if (subdiv == NULL) {
+    /* Happens on bad topology, ut also on empty input mesh. */
+    return;
+  }
+  BKE_subdiv_displacement_attach_from_multires(subdiv, mesh, mmd);
+  BKE_subdiv_deform_coarse_vertices(subdiv, mesh, vertex_cos, num_verts);
+  if (subdiv != runtime_data->subdiv) {
+    BKE_subdiv_free(subdiv);
+  }
+}
+
 ModifierTypeInfo modifierType_Multires = {
     /* name */ "Multires",
     /* structName */ "MultiresModifierData",
@@ -237,7 +268,7 @@ ModifierTypeInfo modifierType_Multires = {
 
     /* copyData */ copyData,
 
-    /* deformVerts */ NULL,
+    /* deformVerts */ deformVerts,
     /* deformMatrices */ NULL,
     /* deformVertsEM */ NULL,
     /* deformMatricesEM */ NULL,