From 3c0c1717a98951f6e0809911aaef12be3d29d37b Mon Sep 17 00:00:00 2001
From: Alexei Kotov <alexdobrohotov@yandex.ru>
Date: Thu, 28 Mar 2024 07:43:33 +0300
Subject: [PATCH] Fix red-green normal map handling for terrain

---
 apps/opencs/model/world/data.cpp          |  1 -
 apps/openmw/mwrender/renderingmanager.cpp |  1 -
 components/sceneutil/util.cpp             | 14 ++++++++++++++
 components/sceneutil/util.hpp             |  2 ++
 components/shader/shadervisitor.cpp       | 15 +++++----------
 components/terrain/material.cpp           | 15 ++++++++++++++-
 6 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/apps/opencs/model/world/data.cpp b/apps/opencs/model/world/data.cpp
index 4198e1b980..470ce04131 100644
--- a/apps/opencs/model/world/data.cpp
+++ b/apps/opencs/model/world/data.cpp
@@ -152,7 +152,6 @@ CSMWorld::Data::Data(ToUTF8::FromType encoding, const Files::PathContainer& data
     mResourceSystem
         = std::make_unique<Resource::ResourceSystem>(mVFS.get(), expiryDelay, &mEncoder.getStatelessEncoder());
 
-    // FIXME: this is severely out of date (see #7595)
     Shader::ShaderManager::DefineMap defines
         = mResourceSystem->getSceneManager()->getShaderManager().getGlobalDefines();
     Shader::ShaderManager::DefineMap shadowDefines = SceneUtil::ShadowManager::getShadowsDisabledDefines();
diff --git a/apps/openmw/mwrender/renderingmanager.cpp b/apps/openmw/mwrender/renderingmanager.cpp
index d5c5321f8e..dc71e455b2 100644
--- a/apps/openmw/mwrender/renderingmanager.cpp
+++ b/apps/openmw/mwrender/renderingmanager.cpp
@@ -446,7 +446,6 @@ namespace MWRender
         globalDefines["useOVR_multiview"] = "0";
         globalDefines["numViews"] = "1";
         globalDefines["disableNormals"] = "1";
-        globalDefines["reconstructNormalZ"] = "0";
 
         for (auto itr = lightDefines.begin(); itr != lightDefines.end(); itr++)
             globalDefines[itr->first] = itr->second;
diff --git a/components/sceneutil/util.cpp b/components/sceneutil/util.cpp
index ab600de11d..a5629ee092 100644
--- a/components/sceneutil/util.cpp
+++ b/components/sceneutil/util.cpp
@@ -286,4 +286,18 @@ namespace SceneUtil
         mOperationQueue->add(operation);
     }
 
+    bool isRedGreenPixelFormat(GLenum format)
+    {
+        switch (format)
+        {
+            case GL_RG:
+            case GL_RG_INTEGER:
+            case GL_COMPRESSED_RED_GREEN_RGTC2_EXT:
+            case GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT:
+                return true;
+        }
+
+        return false;
+    }
+
 }
diff --git a/components/sceneutil/util.hpp b/components/sceneutil/util.hpp
index 29fee09176..0f4b82bbe0 100644
--- a/components/sceneutil/util.hpp
+++ b/components/sceneutil/util.hpp
@@ -112,6 +112,8 @@ namespace SceneUtil
     protected:
         osg::ref_ptr<osg::OperationQueue> mOperationQueue;
     };
+
+    bool isRedGreenPixelFormat(GLenum format);
 }
 
 #endif
diff --git a/components/shader/shadervisitor.cpp b/components/shader/shadervisitor.cpp
index 3867f1f43e..600e35a22a 100644
--- a/components/shader/shadervisitor.cpp
+++ b/components/shader/shadervisitor.cpp
@@ -26,6 +26,7 @@
 #include <components/sceneutil/morphgeometry.hpp>
 #include <components/sceneutil/riggeometry.hpp>
 #include <components/sceneutil/riggeometryosgaextension.hpp>
+#include <components/sceneutil/util.hpp>
 #include <components/settings/settings.hpp>
 #include <components/stereo/stereomanager.hpp>
 #include <components/vfs/manager.hpp>
@@ -445,17 +446,11 @@ namespace Shader
 
             if (normalMap != nullptr && normalMap->getImage(0))
             {
-                // Special handling for red-green normal maps (e.g. BC5 or R8G8).
-                switch (normalMap->getImage(0)->getPixelFormat())
+                // Special handling for red-green normal maps (e.g. BC5 or R8G8)
+                if (SceneUtil::isRedGreenPixelFormat(normalMap->getImage(0)->getPixelFormat()))
                 {
-                    case GL_RG:
-                    case GL_RG_INTEGER:
-                    case GL_COMPRESSED_RED_GREEN_RGTC2_EXT:
-                    case GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT:
-                    {
-                        mRequirements.back().mReconstructNormalZ = true;
-                        mRequirements.back().mNormalHeight = false;
-                    }
+                    mRequirements.back().mReconstructNormalZ = true;
+                    mRequirements.back().mNormalHeight = false;
                 }
             }
 
diff --git a/components/terrain/material.cpp b/components/terrain/material.cpp
index fafe2dcb58..10dbeb9838 100644
--- a/components/terrain/material.cpp
+++ b/components/terrain/material.cpp
@@ -10,6 +10,7 @@
 
 #include <components/resource/scenemanager.hpp>
 #include <components/sceneutil/depth.hpp>
+#include <components/sceneutil/util.hpp>
 #include <components/shader/shadermanager.hpp>
 #include <components/stereo/stereomanager.hpp>
 
@@ -271,18 +272,30 @@ namespace Terrain
                     stateset->addUniform(UniformCollection::value().mBlendMap);
                 }
 
+                bool parallax = it->mNormalMap && it->mParallax;
+                bool reconstructNormalZ = false;
+
                 if (it->mNormalMap)
                 {
                     stateset->setTextureAttributeAndModes(2, it->mNormalMap);
                     stateset->addUniform(UniformCollection::value().mNormalMap);
+
+                    // Special handling for red-green normal maps (e.g. BC5 or R8G8).
+                    const osg::Image* image = it->mNormalMap->getImage(0);
+                    if (image && SceneUtil::isRedGreenPixelFormat(image->getPixelFormat()))
+                    {
+                        reconstructNormalZ = true;
+                        parallax = false;
+                    }
                 }
 
                 Shader::ShaderManager::DefineMap defineMap;
                 defineMap["normalMap"] = (it->mNormalMap) ? "1" : "0";
                 defineMap["blendMap"] = (!blendmaps.empty()) ? "1" : "0";
                 defineMap["specularMap"] = it->mSpecular ? "1" : "0";
-                defineMap["parallax"] = (it->mNormalMap && it->mParallax) ? "1" : "0";
+                defineMap["parallax"] = parallax ? "1" : "0";
                 defineMap["writeNormals"] = (it == layers.end() - 1) ? "1" : "0";
+                defineMap["reconstructNormalZ"] = reconstructNormalZ ? "1" : "0";
                 Stereo::shaderStereoDefines(defineMap);
 
                 stateset->setAttributeAndModes(shaderManager.getProgram("terrain", defineMap));