Weather-related fixes (incl. bug #4783)

Simplify some calculations
Fix Blizzard weather direction
Fix sky direction during storm

CHANGELOG.md

@@ -55,6 +55,7 @@
     Bug #4768: Fallback numerical value recovery chokes on invalid arguments
     Bug #4775: Slowfall effect resets player jumping flag
     Bug #4778: Interiors of Illusion puzzle in Sotha Sil Expanded mod is broken
+    Bug #4783: Blizzard behavior is incorrect
     Bug #4787: Sneaking makes 1st person walking/bobbing animation super-slow
     Bug #4797: Player sneaking and running stances are not accounted for when in air
     Bug #4800: Standing collisions are not updated immediately when an object is teleported without a cell change

apps/openmw/mwrender/sky.cpp

@@ -225,7 +225,7 @@ protected:
     virtual void apply(osg::StateSet *stateset, osg::NodeVisitor *nv)
     {
         osg::TexMat* texMat = static_cast<osg::TexMat*>(stateset->getTextureAttribute(0, osg::StateAttribute::TEXMAT));
-        texMat->setMatrix(osg::Matrix::translate(osg::Vec3f(0, mAnimationTimer, 0.f)));
+        texMat->setMatrix(osg::Matrix::translate(osg::Vec3f(0, -mAnimationTimer, 0.f)));
 
         stateset->setTextureAttribute(0, mTexture, osg::StateAttribute::ON|osg::StateAttribute::OVERRIDE);
         stateset->setTextureAttribute(1, mTexture, osg::StateAttribute::ON|osg::StateAttribute::OVERRIDE);
@@ -1108,7 +1108,7 @@ SkyManager::SkyManager(osg::Group* parentNode, Resource::SceneManager* sceneMana
     , mMonth(0)
     , mCloudAnimationTimer(0.f)
     , mRainTimer(0.f)
-    , mStormDirection(0,-1,0)
+    , mStormDirection(0,1,0)
     , mClouds()
     , mNextClouds()
     , mCloudBlendFactor(0.0f)
@@ -1597,10 +1597,14 @@ void SkyManager::update(float duration)
         osg::Quat quat;
         quat.makeRotate(osg::Vec3f(0,1,0), mStormDirection);
 
+        mCloudNode->setAttitude(quat);
         if (mParticleNode)
+        {
+            // Morrowind deliberately rotates the blizzard mesh, so so should we.
+            if (mCurrentParticleEffect == "meshes\\blizzard.nif")
+                quat.makeRotate(osg::Vec3f(-1,0,0), mStormDirection);
             mParticleNode->setAttitude(quat);
-
-        mCloudNode->setAttitude(quat);
+        }
     }
     else
         mCloudNode->setAttitude(osg::Quat());
@@ -1636,7 +1640,7 @@ void SkyManager::updateRainParameters()
 {
     if (mRainShooter)
     {
-        float angle = -std::atan2(1, 50.f/mWindSpeed);
+        float angle = -std::atan(mWindSpeed/50.f);
         mRainShooter->setVelocity(osg::Vec3f(0, mRainSpeed*std::sin(angle), -mRainSpeed/std::cos(angle)));
         mRainShooter->setAngle(angle);
 

apps/openmw/mwworld/weather.cpp

@@ -661,17 +661,6 @@ void WeatherManager::playerTeleported(const std::string& playerRegion, bool isEx
     }
 }
 
-osg::Vec3f WeatherManager::calculateStormDirection()
-{
-    osg::Vec3f playerPos (MWMechanics::getPlayer().getRefData().getPosition().asVec3());
-    playerPos.z() = 0;
-    osg::Vec3f redMountainPos (25000, 70000, 0);
-    osg::Vec3f stormDirection = (playerPos - redMountainPos);
-    stormDirection.normalize();
-
-    return stormDirection;
-}
-
 float WeatherManager::calculateWindSpeed(int weatherId, float currentSpeed)
 {
     float targetSpeed = std::min(8.0f * mWeatherSettings[weatherId].mWindSpeed, 70.f);
@@ -682,15 +671,7 @@ float WeatherManager::calculateWindSpeed(int weatherId, float currentSpeed)
     float updatedSpeed = (Misc::Rng::rollClosedProbability() - 0.5f) * multiplier * targetSpeed + currentSpeed;
 
     if (updatedSpeed > 0.5f * targetSpeed && updatedSpeed < 2.f * targetSpeed)
-    {
         currentSpeed = updatedSpeed;
-    }
-
-    // Take in account direction to the Red Mountain, when needed
-    if (weatherId == 6 || weatherId == 7)
-    {
-        currentSpeed = (calculateStormDirection() * currentSpeed).length();
-    }
 
     return currentSpeed;
 }
@@ -750,7 +731,16 @@ void WeatherManager::update(float duration, bool paused, const TimeStamp& time,
 
     if (mIsStorm)
     {
-        mStormDirection = calculateStormDirection();
+        osg::Vec3f stormDirection(0, 1, 0);
+        if (mResult.mParticleEffect == "meshes\\ashcloud.nif" || mResult.mParticleEffect == "meshes\\blightcloud.nif")
+        {
+            osg::Vec3f playerPos (MWMechanics::getPlayer().getRefData().getPosition().asVec3());
+            playerPos.z() = 0;
+            osg::Vec3f redMountainPos (25000, 70000, 0);
+            stormDirection = (playerPos - redMountainPos);
+            stormDirection.normalize();
+        }
+        mStormDirection = stormDirection;
         mRendering.getSkyManager()->setStormDirection(mStormDirection);
     }
 

apps/openmw/mwworld/weather.hpp

@@ -370,7 +370,6 @@ namespace MWWorld
         bool updateWeatherRegion(const std::string& playerRegion);
         void updateWeatherTransitions(const float elapsedRealSeconds);
         void forceWeather(const int weatherID);
-        osg::Vec3f calculateStormDirection();
 
         bool inTransition();
         void addWeatherTransition(const int weatherID);