From 8fd71fe4ad8e8a6aaa8d1e71abfb3db16e9fd0bd Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Sun, 4 Nov 2018 12:42:34 +0100
Subject: [PATCH] fix rain delay when exiting water

When the particle system updates its internal state noting that it's
been culled, it stops emitting any further particles. Prevent it from
having that knowledge.

v2: Fix off-by-one-frame error following review by @AnyOldName3
---
 CHANGELOG.md                 |  1 +
 apps/openmw/mwrender/sky.cpp | 19 +++++++++++++++++--
 apps/openmw/mwrender/sky.hpp |  1 +
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d50c96ef49..7880bb2a5b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 0.46.0
 ------
 
+    Bug #4540: Rain delay when exiting water
     Feature #2229: Improve pathfinding AI
     Feature #3442: Default values for fallbacks from ini file
     Task #4686: Upgrade media decoder to a more current FFmpeg API
diff --git a/apps/openmw/mwrender/sky.cpp b/apps/openmw/mwrender/sky.cpp
index d6a0b9f019..0ea0905a61 100644
--- a/apps/openmw/mwrender/sky.cpp
+++ b/apps/openmw/mwrender/sky.cpp
@@ -401,11 +401,15 @@ public:
     {
     }
 
-    virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
+    bool isUnderwater()
     {
         osg::Vec3f eyePoint = mCameraRelativeTransform->getLastEyePoint();
+        return mEnabled && eyePoint.z() < mWaterLevel;
+    }
 
-        if (mEnabled && eyePoint.z() < mWaterLevel)
+    virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
+    {
+        if (isUnderwater())
             return;
 
         traverse(node, nv);
@@ -1575,6 +1579,8 @@ void SkyManager::update(float duration)
             mRainIntensityUniform->set((float) mWeatherAlpha);
     }
 
+    switchUnderwaterRain();
+
     if (mIsStorm)
     {
         osg::Quat quat;
@@ -1626,6 +1632,15 @@ void SkyManager::updateRainParameters()
     }
 }
 
+void SkyManager::switchUnderwaterRain()
+{
+    if (!mRainParticleSystem)
+        return;
+
+    bool freeze = mUnderwaterSwitch->isUnderwater();
+    mRainParticleSystem->setFrozen(freeze);
+}
+
 void SkyManager::setWeather(const WeatherResult& weather)
 {
     if (!mCreated) return;
diff --git a/apps/openmw/mwrender/sky.hpp b/apps/openmw/mwrender/sky.hpp
index a9345cdb41..e70f165213 100644
--- a/apps/openmw/mwrender/sky.hpp
+++ b/apps/openmw/mwrender/sky.hpp
@@ -180,6 +180,7 @@ namespace MWRender
 
         void createRain();
         void destroyRain();
+        void switchUnderwaterRain();
         void updateRainParameters();
 
         Resource::SceneManager* mSceneManager;