== Multires ==

Fixed bug #23657, "Modifiers dosen't work when you select diffrent mesh for object"

Multires modifier now adds empty mdisps if they're missing, rather than displaying a warning
Switching an object's mesh will now check for a multires modifier; if found the modifier's total number of levels are reset to match the mesh's mdisps
Switching the mesh also forces a multires update so that sculpted changes aren't lost

source/blender/blenkernel/BKE_modifier.h

@@ -321,6 +321,9 @@ struct LinkNode *modifiers_calcDataMasks(struct Scene *scene,
 										 int required_mode);
 struct ModifierData  *modifiers_getVirtualModifierList(struct Object *ob);
 
+/* ensure modifier correctness when changing ob->data */
+void test_object_modifiers(struct Object *ob);
+
 /* here for do_versions */
 void modifier_mdef_compact_influences(struct ModifierData *md);
 

source/blender/blenkernel/BKE_multires.h

@@ -44,6 +44,8 @@ void multires_force_update(struct Object *ob);
 void multires_force_render_update(struct Object *ob);
 void multires_force_external_reload(struct Object *ob);
 
+void multiresModifier_set_levels_from_disps(struct MultiresModifierData *mmd, struct Object *ob);
+
 struct DerivedMesh *multires_dm_create_from_derived(struct MultiresModifierData*,
 	int local_mmd, struct DerivedMesh*, struct Object *, int, int);
 

source/blender/blenkernel/intern/mesh.c

@@ -51,6 +51,8 @@
 #include "BKE_displist.h"
 #include "BKE_library.h"
 #include "BKE_material.h"
+#include "BKE_modifier.h"
+#include "BKE_multires.h"
 #include "BKE_key.h"
 /* these 2 are only used by conversion functions */
 #include "BKE_curve.h"
@@ -492,6 +494,8 @@ Mesh *get_mesh(Object *ob)
 void set_mesh(Object *ob, Mesh *me)
 {
 	Mesh *old=0;
+
+	multires_force_update(ob);
 	
 	if(ob==0) return;
 	
@@ -504,6 +508,8 @@ void set_mesh(Object *ob, Mesh *me)
 	}
 	
 	test_object_materials((ID *)me);
+
+	test_object_modifiers(ob);
 }
 
 /* ************** make edges in a Mesh, for outside of editmode */

source/blender/blenkernel/intern/modifier.c

@@ -49,6 +49,7 @@
 #include "BKE_bmesh.h"
 #include "BKE_cloth.h"
 #include "BKE_key.h"
+#include "BKE_multires.h"
 
 #include "MOD_modifiertypes.h"
 
@@ -526,5 +527,21 @@ void modifier_freeTemporaryData(ModifierData *md)
 	}
 }
 
+/* ensure modifier correctness when changing ob->data */
+void test_object_modifiers(Object *ob)
+{
+	ModifierData *md;
 
+	/* just multires checked for now, since only multires
+	   modifies mesh data */
 
+	if(ob->type != OB_MESH) return;
+
+	for(md = ob->modifiers.first; md; md = md->next) {
+		if(md->type == eModifierType_Multires) {
+			MultiresModifierData *mmd = (MultiresModifierData*)md;
+
+			multiresModifier_set_levels_from_disps(mmd, ob);
+		}
+	}
+}

source/blender/blenkernel/intern/multires.c

@@ -275,6 +275,40 @@ int multiresModifier_reshapeFromDeformMod(Scene *scene, MultiresModifierData *mm
 	return result;
 }
 
+/* reset the multires levels to match the number of mdisps */
+void multiresModifier_set_levels_from_disps(MultiresModifierData *mmd, Object *ob)
+{
+	Mesh *me = ob->data;
+	MDisps *mdisp;
+	int i;
+
+	mdisp = CustomData_get_layer(&me->fdata, CD_MDISPS);
+
+	if(mdisp) {
+		for(i = 0; i < me->totface; ++i, ++mdisp) {
+			int S = me->mface[i].v4 ? 4 : 3;
+
+			if(mdisp->totdisp == 0) continue;
+
+			while(1) {
+				int side = (1 << (mmd->totlvl-1)) + 1;
+				int lvl_totdisp = side*side*S;
+				if(mdisp->totdisp == lvl_totdisp)
+					break;
+				else if(mdisp->totdisp < lvl_totdisp)
+					--mmd->totlvl;
+				else
+					++mmd->totlvl;
+					
+			}
+		}
+
+		mmd->lvl = MIN2(mmd->sculptlvl, mmd->totlvl);
+		mmd->sculptlvl = MIN2(mmd->sculptlvl, mmd->totlvl);
+		mmd->renderlvl = MIN2(mmd->renderlvl, mmd->totlvl);
+	}
+}
+
 static void multires_set_tot_mdisps(Mesh *me, int lvl)
 {
 	MDisps *mdisps= CustomData_get_layer(&me->fdata, CD_MDISPS);

source/blender/modifiers/intern/MOD_multires.c

@@ -72,8 +72,8 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob, DerivedMesh *dm,
 
 	if(mmd->totlvl) {
 		if(!CustomData_get_layer(&me->fdata, CD_MDISPS)) {
-			/* multires can't work without displacement layer */
-			modifier_setError(md, "Modifier needs mesh with displacement data.");
+			/* multires always needs a displacement layer */
+			CustomData_add_layer(&me->fdata, CD_MDISPS, CD_CALLOC, NULL, me->totface);
 			return dm;
 		}
 	}