better transitions

apps/openmw/mwrender/sky.cpp

@@ -659,7 +659,10 @@ namespace MWRender
                     mParticleNode->addChild(program);
 
                     for (int particleIndex = 0; particleIndex < ps->numParticles(); ++particleIndex)
+                    {
                         ps->getParticle(particleIndex)->setAlphaRange(osgParticle::rangef(mPrecipitationAlpha, mPrecipitationAlpha));
+                        ps->getParticle(particleIndex)->update(0, true);
+                    }
 
                     ps->getOrCreateStateSet();
                     ps->setUserValue("simpleLighting", true);

files/shaders/sky_fragment.glsl

@@ -29,6 +29,9 @@ void paintClouds(inout vec4 color)
     color = texture2D(diffuseMap, diffuseMapUV);
     color.a *= passColor.a * opacity;
     color.xyz = clamp(color.xyz * gl_FrontMaterial.emission.xyz, 0.0, 1.0);
+
+    // ease transition between clear color and atmosphere/clouds
+    color = mix(vec4(gl_Fog.color.xyz, color.a), color, passColor.a * passColor.a);
 }
 
 void paintMoon(inout vec4 color)