Rewrite flickering/pulsing to work more like vanilla (bug #4952)

CHANGELOG.md

@@ -84,6 +84,7 @@
     Bug #4945: Poor random magic magnitude distribution
     Bug #4947: Player character doesn't use lip animation
     Bug #4948: Footstep sounds while levitating on ground level
+    Bug #4952: Torches held by NPCs flicker too quickly
     Bug #4961: Flying creature combat engagement takes z-axis into account
     Bug #4963: Enchant skill progress is incorrect
     Bug #4964: Multiple effect spell projectile sounds play louder than vanilla

components/sceneutil/lightcontroller.cpp

@@ -8,48 +8,16 @@
 
 #include <components/misc/rng.hpp>
 
-namespace
-{
-
-    float pulseAmplitude(float time)
-    {
-        return std::sin(time);
-    }
-
-    float flickerAmplitude(float time)
-    {
-        static const float fb = 1.17024f;
-        static const float f[3] = { 1.5708f,   4.18774f, 5.19934f };
-        static const float o[3] = { 0.804248f, 2.11115f, 3.46832f };
-        static const float m[3] = { 1.0f,      0.785f,   0.876f   };
-        static const float s = 0.394f;
-
-        float v = 0.0f;
-        for(int i = 0;i < 3;++i)
-            v += std::sin(fb*time*f[i] + o[i])*m[i];
-        return v * s;
-    }
-
-    float flickerFrequency(float phase)
-    {
-        static const float fa = 0.785398f;
-        static const float tdo = 0.94f;
-        static const float tdm = 2.48f;
-
-        return tdo + tdm*std::sin(fa * phase);
-    }
-
-}
-
 namespace SceneUtil
 {
 
     LightController::LightController()
         : mType(LT_Normal)
-        , mPhase((Misc::Rng::rollClosedProbability() * 2.f - 1.f) * 500.f)
-        , mDeltaCount(0.f)
-        , mDirection(1.f)
+        , mPhase(0.25f + Misc::Rng::rollClosedProbability() * 0.75f)
+        , mBrightness(0.675f)
+        , mStartTime(0.0)
         , mLastTime(0.0)
+        , mTicksToAdvance(0.f)
     {
     }
 
@@ -61,66 +29,40 @@ namespace SceneUtil
     void LightController::operator ()(osg::Node* node, osg::NodeVisitor* nv)
     {
         double time = nv->getFrameStamp()->getSimulationTime();
+        if (mStartTime == 0)
+            mStartTime = time;
 
         // disabled early out, light state needs to be set every frame regardless of change, due to the double buffering
         //if (time == mLastTime)
         //    return;
 
-        float dt = static_cast<float>(time - mLastTime);
-        mLastTime = time;
-
-        float brightness = 1.0f;
-        float cycle_time;
-        float time_distortion;
-
-        if(mType == LT_Pulse || mType == LT_PulseSlow)
+        if (mType == LT_Normal)
         {
-            cycle_time = 2.0f * osg::PI;
-            time_distortion = 3.0f;
+            static_cast<SceneUtil::LightSource*>(node)->getLight(nv->getTraversalNumber())->setDiffuse(mDiffuseColor);
+            traverse(node, nv);
+            return;
         }
-        else
-        {
-            static const float fa = osg::PI / 4.0f;
-            static const float phase_wavelength = 120.0f * osg::PI / fa;
 
-            cycle_time = 500.0f;
-            mPhase = std::fmod(mPhase + dt, phase_wavelength);
-            time_distortion = flickerFrequency(mPhase);
-        }
+        // Updating flickering at 15 FPS like vanilla.
+        constexpr float updateRate = 15.f;
+        mTicksToAdvance = static_cast<float>(time - mStartTime - mLastTime) * updateRate * 0.25f + mTicksToAdvance * 0.75f;
+        mLastTime = time - mStartTime;
 
-        mDeltaCount += mDirection*dt*time_distortion;
-        if(mDirection > 0 && mDeltaCount > +cycle_time)
-        {
-            mDirection = -1.0f;
-            float extra = mDeltaCount - cycle_time;
-            mDeltaCount -= 2*extra;
-        }
-        if(mDirection < 0 && mDeltaCount < -cycle_time)
-        {
-            mDirection = +1.0f;
-            float extra = cycle_time - mDeltaCount;
-            mDeltaCount += 2*extra;
-        }
-
-        static const float fast = 4.0f/1.0f;
-        static const float slow = 1.0f/1.0f;
+        float speed = (mType == LT_Flicker || mType == LT_Pulse) ? 0.1f : 0.05f;
+        if (mBrightness >= mPhase)
+            mBrightness -= mTicksToAdvance * speed;
+        else
+            mBrightness += mTicksToAdvance * speed;
 
-        // These formulas are just guesswork, but they work pretty well
-        if(mType == LT_Normal)
+        if (std::abs(mBrightness - mPhase) < speed)
         {
-            // Less than 1/255 light modifier for a constant light:
-            brightness = 1.0f + flickerAmplitude(mDeltaCount*slow)/255.0f;
+            if (mType == LT_Flicker || mType == LT_FlickerSlow)
+                mPhase = 0.25f + Misc::Rng::rollClosedProbability() * 0.75f;
+            else // if (mType == LT_Pulse || mType == LT_PulseSlow)
+                mPhase = mPhase <= 0.5f ? 1.f : 0.25f;
         }
-        else if(mType == LT_Flicker)
-            brightness = 0.75f + flickerAmplitude(mDeltaCount*fast)*0.25f;
-        else if(mType == LT_FlickerSlow)
-            brightness = 0.75f + flickerAmplitude(mDeltaCount*slow)*0.25f;
-        else if(mType == LT_Pulse)
-            brightness = 0.7f + pulseAmplitude(mDeltaCount*fast)*0.3f;
-        else if(mType == LT_PulseSlow)
-            brightness = 0.7f + pulseAmplitude(mDeltaCount*slow)*0.3f;
-
-        static_cast<SceneUtil::LightSource*>(node)->getLight(nv->getTraversalNumber())->setDiffuse(mDiffuseColor * brightness);
+
+        static_cast<SceneUtil::LightSource*>(node)->getLight(nv->getTraversalNumber())->setDiffuse(mDiffuseColor * mBrightness);
 
         traverse(node, nv);
     }

components/sceneutil/lightcontroller.hpp

@@ -32,9 +32,10 @@ namespace SceneUtil
         LightType mType;
         osg::Vec4f mDiffuseColor;
         float mPhase;
-        float mDeltaCount;
-        int mDirection;
+        float mBrightness;
+        double mStartTime;
         double mLastTime;
+        float mTicksToAdvance;
     };
 
 }