#4604 Warn user off high settings when on low-RAM hardware

indra/newview/llfloaterpreference.cpp

@@ -758,6 +758,7 @@ void LLFloaterPreference::onOpen(const LLSD& key)
 
     // Forget previous language changes.
     mLanguageChanged = false;
+    mLastQualityLevel = gSavedSettings.getU32("RenderQualityPerformance");
 
     // Display selected maturity icons.
     onChangeMaturity();
@@ -1327,6 +1328,33 @@ void LLFloaterPreference::onCommitWindowedMode()
 void LLFloaterPreference::onChangeQuality(const LLSD& data)
 {
     U32 level = (U32)(data.asReal());
+    constexpr U32 LVL_HIGH = 4;
+    if (level >= LVL_HIGH && mLastQualityLevel < level)
+    {
+        constexpr U32 LOW_MEM_THRESHOLD = 4097;
+        U32 total_mem = (U32Megabytes)LLMemory::getMaxMemKB();
+        if (total_mem < LOW_MEM_THRESHOLD)
+        {
+            LLSD args;
+            args["TOTAL_MEM"] = LLSD::Integer(total_mem);
+            LLNotificationsUtil::add("PreferenceQualityWithLowMemory", args, LLSD(), [this](const LLSD& notification, const LLSD& response)
+            {
+                S32 option = LLNotificationsUtil::getSelectedOption(notification, response);
+                // If cancel pressed
+                if (option == 1)
+                {
+                    constexpr U32 LVL_MED_PLUS = 3;
+                    gSavedSettings.setU32("RenderQualityPerformance", LVL_MED_PLUS);
+                    mLastQualityLevel = LVL_MED_PLUS;
+                    LLFeatureManager::getInstance()->setGraphicsLevel(LVL_MED_PLUS, true);
+                    refreshEnabledGraphics();
+                    refresh();
+                }
+            }
+            );
+        }
+    }
+    mLastQualityLevel = level;
     LLFeatureManager::getInstance()->setGraphicsLevel(level, true);
     refreshEnabledGraphics();
     refresh();

indra/newview/llfloaterpreference.h

@@ -218,6 +218,7 @@ private:
     bool mGotPersonalInfo;
     bool mLanguageChanged;
     bool mAvatarDataInitialized;
+    U32 mLastQualityLevel = 0;
     std::string mPriorInstantMessageLogPath;
 
     bool mOriginalHideOnlineStatus;

indra/newview/skins/default/xui/en/notifications.xml

@@ -12145,6 +12145,17 @@ Cannot create large prims that intersect other residents.  Please re-try when ot
      yestext="OK"/>
   </notification>
 
+  <notification
+   icon="alertmodal.tga"
+   name="PreferenceQualityWithLowMemory"
+   type="alert">
+Your system has [TOTAL_MEM]MB of memory, which might not be enough to run viewer at higher settings and might result in issues.
+      <usetemplate
+       name="okcancelbuttons"
+       notext="Cancel"
+       yestext="Continue"/>
+  </notification>
+
   <notification
    icon="alertmodal.tga"
    name="DefaultObjectPermissions"