Initial stab at OSG plugin checker

It doesn't work yet due to osgDB::listAllAvailablePlugins returning a list of paths to dynamic libraries.
That means:
* the check fails when the required plugin is linked statically.
* we're going to have to do something to slice up the filenames.
* there'll probably be unicode errors when the OpenMW installation path isn't representable by the current eight-bit code page on Windows.

Alternatively, we can switch to listing the required file extension support, and use osgDB::Registry::instance()->getReaderWriterList() and each element's supportedExtensions() function, but I don't think we've actually got that list of extensions anywhere and it might get desynced with the existing list of plugins if we add more.

apps/openmw/main.cpp

@@ -2,6 +2,7 @@
 #include <components/fallback/fallback.hpp>
 #include <components/fallback/validate.hpp>
 #include <components/files/configurationmanager.hpp>
+#include <components/misc/osgpluginchecker.hpp>
 #include <components/misc/rng.hpp>
 #include <components/platform/platform.hpp>
 #include <components/version/version.hpp>
@@ -228,6 +229,9 @@ int runApplication(int argc, char* argv[])
 
     if (parseOptions(argc, argv, *engine, cfgMgr))
     {
+        if (!Misc::checkRequiredOSGPluginsArePresent())
+            return 1;
+
         engine->go();
     }
 

components/CMakeLists.txt

@@ -40,6 +40,11 @@ endif (GIT_CHECKOUT)
 
 list (APPEND COMPONENT_FILES "${OpenMW_BINARY_DIR}/${VERSION_CPP_FILE}")
 
+# OSG plugin checker
+set(OSG_PLUGIN_CHECKER_CPP_FILE "components/misc/osgpluginchecker.cpp")
+configure_file("${OpenMW_SOURCE_DIR}/${OSG_PLUGIN_CHECKER_CPP_FILE}.in" "${OpenMW_BINARY_DIR}/${OSG_PLUGIN_CHECKER_CPP_FILE}")
+list(APPEND COMPONENT_FILES "${OpenMW_BINARY_DIR}/${OSG_PLUGIN_CHECKER_CPP_FILE}")
+
 # source files
 
 add_component_dir (lua
@@ -274,8 +279,8 @@ add_component_dir (esm4
 
 add_component_dir (misc
     barrier budgetmeasurement color compression constants convert coordinateconverter display endianness float16 frameratelimiter
-    guarded math mathutil messageformatparser notnullptr objectpool osguservalues progressreporter resourcehelpers rng
+    guarded math mathutil messageformatparser notnullptr objectpool osgpluginchecker osguservalues progressreporter resourcehelpers
-    strongtypedef thread timeconvert timer tuplehelpers tuplemeta utf8stream weakcache windows
+    rng strongtypedef thread timeconvert timer tuplehelpers tuplemeta utf8stream weakcache windows
     )
 
 add_component_dir (misc/strings

components/misc/osgpluginchecker.cpp.in

@@ -0,0 +1,47 @@
+#include "components/misc/osgpluginchecker.hpp"
+
+#include <components/debug/debuglog.hpp>
+
+#include <osgDB/PluginQuery>
+
+#include <algorithm>
+#include <string_view>
+
+namespace Misc
+{
+    namespace
+    {
+        std::string_view USED_OSG_PLUGINS = "${USED_OSG_PLUGINS}";
+
+        constexpr std::vector<std::string_view> getRequiredOSGPlugins()
+        {
+            std::vector<std::string_view> requiredOSGPlugins;
+            auto currentStart = USED_OSG_PLUGINS.begin();
+            while (currentStart != USED_OSG_PLUGINS.end())
+            {
+                auto currentEnd = std::find(currentStart, USED_OSG_PLUGINS.end(), ';');
+                requiredOSGPlugins.emplace_back(currentStart, currentEnd);
+                if (currentEnd == USED_OSG_PLUGINS.end())
+                    break;
+                currentStart = currentEnd + 1;
+            }
+            return requiredOSGPlugins;
+        }
+    }
+
+    bool checkRequiredOSGPluginsArePresent()
+    {
+        auto availableOSGPlugins = osgDB::listAllAvailablePlugins();
+        auto requiredOSGPlugins = getRequiredOSGPlugins();
+        bool haveAllPlugins = true;
+        for (std::string_view plugin : requiredOSGPlugins)
+        {
+            if (std::find(availableOSGPlugins.begin(), availableOSGPlugins.end(), plugin) == availableOSGPlugins.end())
+            {
+                Log(Debug::Error) << "Missing OSG plugin: " << plugin;
+                haveAllPlugins = false;
+            }
+        }
+        return haveAllPlugins;
+    }
+}

components/misc/osgpluginchecker.hpp

@@ -0,0 +1,9 @@
+#ifndef OPENMW_COMPONENTS_MISC_OSGPLUGINCHECKER_HPP
+#define OPENMW_COMPONENTS_MISC_OSGPLUGINCHECKER_HPP
+
+namespace Misc
+{
+    bool checkRequiredOSGPluginsArePresent();
+}
+
+#endif