From 7573004efc47ac9a6bc9e35653ec3e98106b6b69 Mon Sep 17 00:00:00 2001
From: Evil Eye <malusluminis@hotmail.com>
Date: Mon, 17 Jul 2023 18:00:15 +0200
Subject: [PATCH 1/2] Implement the NegativeLight flag

---
 apps/openmw/mwrender/animation.cpp        | 10 +++-------
 apps/openmw/mwworld/projectilemanager.cpp | 15 ++++-----------
 components/esm3/loadmgef.cpp              |  8 ++++++++
 components/esm3/loadmgef.hpp              |  6 +++++-
 4 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/apps/openmw/mwrender/animation.cpp b/apps/openmw/mwrender/animation.cpp
index 115f49a0b1..5de63030c3 100644
--- a/apps/openmw/mwrender/animation.cpp
+++ b/apps/openmw/mwrender/animation.cpp
@@ -1490,11 +1490,6 @@ namespace MWRender
 
     void Animation::addSpellCastGlow(const ESM::MagicEffect* effect, float glowDuration)
     {
-        osg::Vec4f glowColor(1, 1, 1, 1);
-        glowColor.x() = effect->mData.mRed / 255.f;
-        glowColor.y() = effect->mData.mGreen / 255.f;
-        glowColor.z() = effect->mData.mBlue / 255.f;
-
         if (!mGlowUpdater || (mGlowUpdater->isDone() || (mGlowUpdater->isPermanentGlowUpdater() == true)))
         {
             if (mGlowUpdater && mGlowUpdater->isDone())
@@ -1502,11 +1497,12 @@ namespace MWRender
 
             if (mGlowUpdater && mGlowUpdater->isPermanentGlowUpdater())
             {
-                mGlowUpdater->setColor(glowColor);
+                mGlowUpdater->setColor(effect->getColor());
                 mGlowUpdater->setDuration(glowDuration);
             }
             else
-                mGlowUpdater = SceneUtil::addEnchantedGlow(mObjectRoot, mResourceSystem, glowColor, glowDuration);
+                mGlowUpdater
+                    = SceneUtil::addEnchantedGlow(mObjectRoot, mResourceSystem, effect->getColor(), glowDuration);
         }
     }
 
diff --git a/apps/openmw/mwworld/projectilemanager.cpp b/apps/openmw/mwworld/projectilemanager.cpp
index 785b19ea82..4fdcb4de31 100644
--- a/apps/openmw/mwworld/projectilemanager.cpp
+++ b/apps/openmw/mwworld/projectilemanager.cpp
@@ -136,21 +136,14 @@ namespace
     {
         // Calculate combined light diffuse color from magical effects
         osg::Vec4 lightDiffuseColor;
-        float lightDiffuseRed = 0.0f;
-        float lightDiffuseGreen = 0.0f;
-        float lightDiffuseBlue = 0.0f;
-        for (std::vector<ESM::ENAMstruct>::const_iterator iter(effects.mList.begin()); iter != effects.mList.end();
-             ++iter)
+        for (const ESM::ENAMstruct& enam : effects.mList)
         {
             const ESM::MagicEffect* magicEffect
-                = MWBase::Environment::get().getESMStore()->get<ESM::MagicEffect>().find(iter->mEffectID);
-            lightDiffuseRed += (static_cast<float>(magicEffect->mData.mRed) / 255.f);
-            lightDiffuseGreen += (static_cast<float>(magicEffect->mData.mGreen) / 255.f);
-            lightDiffuseBlue += (static_cast<float>(magicEffect->mData.mBlue) / 255.f);
+                = MWBase::Environment::get().getESMStore()->get<ESM::MagicEffect>().find(enam.mEffectID);
+            lightDiffuseColor += magicEffect->getColor();
         }
         int numberOfEffects = effects.mList.size();
-        lightDiffuseColor = osg::Vec4(lightDiffuseRed / numberOfEffects, lightDiffuseGreen / numberOfEffects,
-            lightDiffuseBlue / numberOfEffects, 1.0f);
+        lightDiffuseColor /= numberOfEffects;
 
         return lightDiffuseColor;
     }
diff --git a/components/esm3/loadmgef.cpp b/components/esm3/loadmgef.cpp
index 68225d44ef..7d3879a341 100644
--- a/components/esm3/loadmgef.cpp
+++ b/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())
diff --git a/components/esm3/loadmgef.hpp b/components/esm3/loadmgef.hpp
index 1b4089e74a..9d68bad609 100644
--- a/components/esm3/loadmgef.hpp
+++ b/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,

From 2fa9462d49aef17609912da7d5c82db550535058 Mon Sep 17 00:00:00 2001
From: Evil Eye <malusluminis@hotmail.com>
Date: Mon, 17 Jul 2023 19:46:12 +0200
Subject: [PATCH 2/2] Add changelog entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ccd063ddbd..a0b64d26f8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -83,6 +83,7 @@
     Feature #7148: Optimize string literal lookup in mwscript
     Feature #7194: Ori to show texture paths
     Feature #7214: Searching in the in-game console
+    Feature #7477: NegativeLight Magic Effect flag
     Task #7113: Move from std::atoi to std::from_char
     Task #7117: Replace boost::scoped_array with std::vector
     Task #7151: Do not use std::strerror to get errno error message