Incorrect low level was used for this case -- it should be
sculpt level, not preview level.
Thanks to Morten Mikkelsen to point on this bug :)
MultiresModifierData *mmd= get_multires_modifier(scene, ob, 0);
Mesh *me= (Mesh*)ob->data;
- *lvl= mmd->lvl;
+ if(ob->mode==OB_MODE_SCULPT) *lvl= mmd->sculptlvl;
+ else *lvl= mmd->lvl;
- if(mmd->lvl==0) {
+ if(*lvl==0) {
DerivedMesh *tmp_dm= CDDM_from_mesh(me, ob);
dm= CDDM_copy(tmp_dm);
tmp_dm->release(tmp_dm);
MultiresModifierData tmp_mmd= *mmd;
DerivedMesh *cddm= CDDM_from_mesh(me, ob);
- tmp_mmd.lvl= mmd->lvl;
+ tmp_mmd.lvl= *lvl;
dm= multires_dm_create_from_derived(&tmp_mmd, 1, cddm, ob, 0, 0);
cddm->release(cddm);
}