Merge branch 'darkmagic' into 'master'

Implement the NegativeLight flag

Closes #7477

See merge request OpenMW/openmw!3240

components/esm3/loadmgef.cpp

@@ -603,6 +603,14 @@ namespace ESM
         mDescription.clear();
     }
 
+    osg::Vec4f MagicEffect::getColor() const
+    {
+        osg::Vec4f color{ mData.mRed / 255.f, mData.mGreen / 255.f, mData.mBlue / 255.f, 1.f };
+        if (mData.mFlags & NegativeLight)
+            return osg::Vec4f(1.f, 1.f, 1.f, 2.f) - color;
+        return color;
+    }
+
     const std::string& MagicEffect::indexToGmstString(int effectID)
     {
         if (effectID < 0 || static_cast<std::size_t>(effectID) >= sGmstEffectIds.size())

components/esm3/loadmgef.hpp

@@ -10,6 +10,8 @@
 #include "components/esm/refid.hpp"
 #include "components/misc/strings/algorithm.hpp"
 
+#include <osg/Vec4>
+
 namespace ESM
 {
 
@@ -55,7 +57,7 @@ namespace ESM
             // Originally modifiable flags
             AllowSpellmaking = 0x200, // Can be used for spellmaking
             AllowEnchanting = 0x400, // Can be used for enchanting
-            NegativeLight = 0x800 // Unused
+            NegativeLight = 0x800 // Inverts the effect's color
         };
 
         enum MagnitudeDisplayType
@@ -113,6 +115,8 @@ namespace ESM
         /// Set record to default state (does not touch the ID/index).
         void blank();
 
+        osg::Vec4f getColor() const;
+
         enum Effects
         {
             WaterBreathing = 0,