Atmosphere no longer does "real" alpha blending to blend with the horizon, this is in preparation for proper underwater viewport BG / fog

apps/openmw/mwrender/sky.cpp

@@ -255,6 +255,7 @@ void SkyManager::create()
     sh::Factory::getInstance().setSharedParameter ("nightFade",
         sh::makeProperty<sh::FloatValue>(new sh::FloatValue(0)));
     sh::Factory::getInstance().setSharedParameter ("atmosphereColour", sh::makeProperty<sh::Vector4>(new sh::Vector4(0,0,0,1)));
+    sh::Factory::getInstance().setSharedParameter ("horizonColour", sh::makeProperty<sh::Vector4>(new sh::Vector4(0,0,0,1)));
 
     sh::Factory::getInstance().setTextureAlias ("cloud_texture_1", "");
     sh::Factory::getInstance().setTextureAlias ("cloud_texture_2", "");
@@ -488,6 +489,13 @@ void SkyManager::setWeather(const MWWorld::WeatherResult& weather)
             weather.mSkyColor.r, weather.mSkyColor.g, weather.mSkyColor.b, weather.mSkyColor.a)));
     }
 
+    if (mFogColour != weather.mFogColor)
+    {
+        mFogColour = weather.mFogColor;
+        sh::Factory::getInstance().setSharedParameter ("horizonColour", sh::makeProperty<sh::Vector4>(new sh::Vector4(
+            weather.mFogColor.r, weather.mFogColor.g, weather.mFogColor.b, weather.mFogColor.a)));
+    }
+
     mCloudSpeed = weather.mCloudSpeed;
 
     if (weather.mNight && mStarsOpacity != weather.mNightFade)

apps/openmw/mwrender/sky.hpp

@@ -211,6 +211,7 @@ namespace MWRender
         float mStarsOpacity;
         Ogre::ColourValue mCloudColour;
         Ogre::ColourValue mSkyColour;
+        Ogre::ColourValue mFogColour;
 
         Ogre::Light* mLightning;
 

files/materials/atmosphere.shader

@@ -18,10 +18,11 @@
     SH_BEGIN_PROGRAM
                 shInput(float, alphaFade)
         shUniform(float4, atmosphereColour)                   @shSharedParameter(atmosphereColour)
+        shUniform(float4, horizonColour)                   @shSharedParameter(horizonColour, horizonColour)
 
     SH_START_PROGRAM
     {
-        shOutputColour(0) = atmosphereColour * float4(1,1,1,alphaFade);
+        shOutputColour(0) = alphaFade * atmosphereColour + (1.f - alphaFade) * horizonColour;
     }
 
 #endif

files/materials/sky.mat

@@ -59,7 +59,6 @@ material openmw_atmosphere
         
         polygon_mode_overrideable off
         
-        scene_blend alpha_blend
         depth_write off
     }
 }