Merge branch 'fog_alpha' into 'master'

Several fixes related to sky blending

See merge request OpenMW/openmw!2046

apps/openmw/mwrender/sky.cpp

@@ -232,6 +232,7 @@ namespace
             camera->setReferenceFrame(osg::Camera::RELATIVE_RF);
             camera->setName("SkyCamera");
             camera->setNodeMask(MWRender::Mask_RenderToTexture);
+            camera->setCullMask(MWRender::Mask_Sky);
             camera->addChild(mEarlyRenderBinRoot);
             SceneUtil::ShadowManager::disableShadowsForStateSet(camera->getOrCreateStateSet());
         }
@@ -283,25 +284,26 @@ namespace MWRender
         if (!mSceneManager->getForceShaders())
             skyroot->getOrCreateStateSet()->setAttributeAndModes(new osg::Program(), osg::StateAttribute::OVERRIDE|osg::StateAttribute::PROTECTED|osg::StateAttribute::ON);
         SceneUtil::ShadowManager::disableShadowsForStateSet(skyroot->getOrCreateStateSet());
-
-        skyroot->setNodeMask(Mask_Sky);
         parentNode->addChild(skyroot);
 
-        mRootNode = skyroot;
-
         mEarlyRenderBinRoot = new osg::Group;
         // render before the world is rendered
         mEarlyRenderBinRoot->getOrCreateStateSet()->setRenderBinDetails(RenderBin_Sky, "RenderBin");
         // Prevent unwanted clipping by water reflection camera's clipping plane
         mEarlyRenderBinRoot->getOrCreateStateSet()->setMode(GL_CLIP_PLANE0, osg::StateAttribute::OFF);
-        mRootNode->addChild(mEarlyRenderBinRoot);
 
         if (enableSkyRTT)
         {
             mSkyRTT = new SkyRTT(Settings::Manager::getVector2("sky rtt resolution", "Fog"), mEarlyRenderBinRoot);
-            mRootNode->addChild(mSkyRTT);
+            skyroot->addChild(mSkyRTT);
+            mRootNode = new osg::Group;
+            skyroot->addChild(mRootNode);
         }
+        else
+            mRootNode = skyroot;
 
+        mRootNode->setNodeMask(Mask_Sky);
+        mRootNode->addChild(mEarlyRenderBinRoot);
         mUnderwaterSwitch = new UnderwaterSwitchCallback(skyroot);
     }
 

components/shader/shadervisitor.cpp

@@ -5,6 +5,7 @@
 #include <set>
 
 #include <osg/AlphaFunc>
+#include <osg/BlendFunc>
 #include <osg/Geometry>
 #include <osg/GLExtensions>
 #include <osg/Material>
@@ -195,6 +196,8 @@ namespace Shader
         , mAlphaFunc(GL_ALWAYS)
         , mAlphaRef(1.0)
         , mAlphaBlend(false)
+        , mBlendFuncOverridden(false)
+        , mAdditiveBlending(false)
         , mNormalHeight(false)
         , mTexStageRequiringTangents(-1)
         , mSoftParticles(false)
@@ -517,6 +520,18 @@ namespace Shader
                         mRequirements.back().mAlphaRef = alpha->getReferenceValue();
                     }
                 }
+                else if (it->first.first == osg::StateAttribute::BLENDFUNC)
+                {
+                    if (!mRequirements.back().mBlendFuncOverridden || it->second.second & osg::StateAttribute::PROTECTED)
+                    {
+                        if (it->second.second & osg::StateAttribute::OVERRIDE)
+                            mRequirements.back().mBlendFuncOverridden = true;
+
+                        const osg::BlendFunc* blend = static_cast<const osg::BlendFunc*>(it->second.first.get());
+                        mRequirements.back().mAdditiveBlending =
+                            blend->getSource() == osg::BlendFunc::SRC_ALPHA && blend->getDestination() == osg::BlendFunc::ONE;
+                    }
+                }
             }
         }
 
@@ -604,6 +619,8 @@ namespace Shader
 
         defineMap["alphaFunc"] = std::to_string(reqs.mAlphaFunc);
 
+        defineMap["additiveBlending"] = reqs.mAdditiveBlending ? "1" : "0";
+
         osg::ref_ptr<osg::StateSet> removedState;
         if ((removedState = getRemovedState(*writableStateSet)) && !mAllowedToModifyStateSets)
             removedState = new osg::StateSet(*removedState, osg::CopyOp::SHALLOW_COPY);

components/shader/shadervisitor.hpp

@@ -102,6 +102,9 @@ namespace Shader
             float mAlphaRef;
             bool mAlphaBlend;
 
+            bool mBlendFuncOverridden;
+            bool mAdditiveBlending;
+
             bool mNormalHeight; // true if normal map has height info in alpha channel
 
             // -1 == no tangents required

files/shaders/fog.glsl

@@ -17,12 +17,21 @@ vec4 applyFogAtDist(vec4 color, float euclideanDist, float linearDist)
 #else
     float fogValue = clamp((dist - gl_Fog.start) * gl_Fog.scale, 0.0, 1.0);
 #endif
+#ifdef ADDITIVE_BLENDING
+    color.xyz *= 1 - fogValue;
+#else
     color.xyz = mix(color.xyz, gl_Fog.color.xyz, fogValue);
+#endif
 
 #if @skyBlending && !@useOVR_multiview
     float fadeValue = clamp((far - dist) / (far - skyBlendingStart), 0.0, 1.0);
+    fadeValue *= fadeValue;
+#ifdef ADDITIVE_BLENDING
+    color.xyz *= fadeValue;
+#else
     vec3 skyColor = texture2D(sky, gl_FragCoord.xy / screenRes).xyz;
-    color.xyz = mix(skyColor, color.xyz, fadeValue * fadeValue);
+    color.xyz = mix(skyColor, color.xyz, fadeValue);
+#endif
 #endif
 
     return color;

files/shaders/objects_fragment.glsl

@@ -77,6 +77,10 @@ uniform float specStrength;
 varying vec3 passViewPos;
 varying vec3 passNormal;
 
+#if @additiveBlending
+#define ADDITIVE_BLENDING
+#endif
+
 #include "vertexcolors.glsl"
 #include "shadows_fragment.glsl"
 #include "lighting.glsl"
@@ -188,7 +192,7 @@ void main()
 
 #endif
 
-    float shadowing = unshadowedLightRatio(passViewPos.z);
+    float shadowing = unshadowedLightRatio(-passViewPos.z);
     vec3 lighting;
 #if !PER_PIXEL_LIGHTING
     lighting = passLighting + shadowDiffuseLighting * shadowing;