Dispel only effects from spells (bug #3995)

apps/openmw/mwmechanics/activespells.cpp

@@ -222,10 +222,23 @@ namespace MWMechanics
         }
     }
 
-    void ActiveSpells::purgeAll(float chance)
+    void ActiveSpells::purgeAll(float chance, bool spellOnly)
     {
         for (TContainer::iterator it = mSpells.begin(); it != mSpells.end(); )
         {
+            const std::string spellId = it->first;
+
+            // if spellOnly is true, dispell only spells. Leave potions, enchanted items etc.
+            if (spellOnly)
+            {
+                const ESM::Spell* spell = MWBase::Environment::get().getWorld()->getStore().get<ESM::Spell>().search(spellId);
+                if (!spell || spell->mData.mType != ESM::Spell::ST_Spell)
+                {
+                    ++it;
+                    continue;
+                }
+            }
+
             if (Misc::Rng::roll0to99() < chance)
                 mSpells.erase(it++);
             else

apps/openmw/mwmechanics/activespells.hpp

@@ -89,7 +89,7 @@ namespace MWMechanics
             void purgeEffect (short effectId, const std::string& sourceId);
 
             /// Remove all active effects, if roll succeeds (for each effect)
-            void purgeAll (float chance);
+            void purgeAll(float chance, bool spellOnly = false);
 
             /// Remove all effects with CASTER_LINKED flag that were cast by \a casterActorId
             void purge (int casterActorId);

apps/openmw/mwmechanics/spellcasting.cpp

@@ -673,7 +673,7 @@ namespace MWMechanics
         }
         else if (target.getClass().isActor() && effectId == ESM::MagicEffect::Dispel)
         {
-            target.getClass().getCreatureStats(target).getActiveSpells().purgeAll(magnitude);
+            target.getClass().getCreatureStats(target).getActiveSpells().purgeAll(magnitude, true);
             return true;
         }
         else if (target.getClass().isActor() && target == getPlayer())

apps/openmw/mwmechanics/spellpriority.cpp

@@ -25,6 +25,14 @@ namespace
         const MWMechanics::ActiveSpells& activeSpells = actor.getClass().getCreatureStats(actor).getActiveSpells();
         for (MWMechanics::ActiveSpells::TIterator it = activeSpells.begin(); it != activeSpells.end(); ++it)
         {
+            // if the effect filter is not specified, take in account only spells effects. Leave potions, enchanted items etc.
+            if (effectFilter == -1)
+            {
+                const ESM::Spell* spell = MWBase::Environment::get().getWorld()->getStore().get<ESM::Spell>().search(it->first);
+                if (!spell || spell->mData.mType != ESM::Spell::ST_Spell)
+                    continue;
+            }
+
             const MWMechanics::ActiveSpells::ActiveSpellParams& params = it->second;
             for (std::vector<MWMechanics::ActiveSpells::ActiveEffect>::const_iterator effectIt = params.mEffects.begin();
                 effectIt != params.mEffects.end(); ++effectIt)